diff --git a/.gitignore b/.gitignore
index c237d0402877332e46b0dbaeb3a4a12c6283bfe7..5861b1e56adb7cc3c87bb3c10d66c1736ea8885c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -33,5 +33,11 @@ src/examples/map_apriltag_save.yaml
 build_release/
 
 IMU.found
+imu.found
+.ccls
+.ccls-cache
+.ccls-root
+compile_commands.json
+.vimspector.json
 est.csv
 /imu.found
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 16e11c7d14548787af08849a911d5821df4c3e06..31887a2e83ced1be3c875fcca9d9d90bd99355be 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,7 +24,7 @@ ENDIF (NOT CMAKE_BUILD_TYPE)
 message(STATUS "Configured to compile in ${CMAKE_BUILD_TYPE} mode.")
 
 #Set Flags
-SET(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -D_REENTRANT")
+SET(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -O0 -D_REENTRANT")
 SET(CMAKE_CXX_FLAGS_RELEASE "-O3 -D_REENTRANT")
 
 #Set compiler according C++11 support
@@ -138,19 +138,23 @@ SET(HDRS_CAPTURE
 SET(HDRS_FACTOR
   include/imu/factor/factor_compass_3d.h
   include/imu/factor/factor_imu.h
+  include/imu/factor/factor_imu2d.h
   )
 SET(HDRS_FEATURE
   include/imu/feature/feature_imu.h
+  include/imu/feature/feature_imu2d.h
   )
 SET(HDRS_LANDMARK
   )
 SET(HDRS_PROCESSOR
   include/imu/processor/processor_compass.h
   include/imu/processor/processor_imu.h
+  include/imu/processor/processor_imu2d.h
   )
 SET(HDRS_SENSOR
   include/imu/sensor/sensor_compass.h
   include/imu/sensor/sensor_imu.h
+  include/imu/sensor/sensor_imu2d.h
   )
 SET(HDRS_SOLVER
   )
@@ -163,6 +167,7 @@ SET(SRCS_COMMON
   )
 SET(SRCS_MATH
   include/imu/math/imu_tools.h
+  include/imu/math/imu2d_tools.h
   )
 SET(SRCS_UTILS
   )
@@ -174,17 +179,21 @@ SET(SRCS_FACTOR
   )
 SET(SRCS_FEATURE
   src/feature/feature_imu.cpp
+  src/feature/feature_imu2d.cpp
   )
 SET(SRCS_LANDMARK
   )
 SET(SRCS_PROCESSOR
   src/processor/processor_compass.cpp
   src/processor/processor_imu.cpp
+  src/processor/processor_imu2d.cpp
   test/processor_imu_UnitTester.cpp
+  test/processor_imu2d_UnitTester.cpp
 )
 SET(SRCS_SENSOR
   src/sensor/sensor_compass.cpp
   src/sensor/sensor_imu.cpp
+  src/sensor/sensor_imu2d.cpp
   )
 SET(SRCS_DTASSC
   )
@@ -192,7 +201,9 @@ SET(SRCS_SOLVER
   )
 SET(SRCS_YAML
   src/yaml/processor_imu_yaml.cpp
+  src/yaml/processor_imu2d_yaml.cpp
   src/yaml/sensor_imu_yaml.cpp
+  src/yaml/sensor_imu2d_yaml.cpp
   )
 #OPTIONALS
 #optional HDRS and SRCS
diff --git a/demos/processor_imu2d.yaml b/demos/processor_imu2d.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..6d8d756c415d5d9db4b32ab80cf1ea06f72736fd
--- /dev/null
+++ b/demos/processor_imu2d.yaml
@@ -0,0 +1,12 @@
+type: "ProcessorImu2d"              # This must match the KEY used in the SensorFactory. Otherwise it is an error.
+
+time_tolerance: 0.0025         # Time tolerance for joining KFs
+unmeasured_perturbation_std: 0.00001
+
+keyframe_vote:
+    voting_active:      false
+    voting_aux_active:  false
+    max_time_span:      2.0   # seconds
+    max_buff_length:  20000    # motion deltas
+    dist_traveled:      2.0   # meters
+    angle_turned:       0.2   # radians (1 rad approx 57 deg, approx 60 deg)
diff --git a/demos/sensor_imu2d.yaml b/demos/sensor_imu2d.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..ce810d4f5f397a7bcb8647e086c026b125fbc936
--- /dev/null
+++ b/demos/sensor_imu2d.yaml
@@ -0,0 +1,9 @@
+type: "SensorImu2d"             # This must match the KEY used in the SensorFactory. Otherwise it is an error.
+
+motion_variances: 
+    a_noise:                0.053     # standard deviation of Acceleration noise (same for all the axis) in m/s2
+    w_noise:                0.0011    # standard deviation of Gyroscope noise (same for all the axis) in rad/sec
+    ab_initial_stdev:       0.800     # m/s2    - initial bias 
+    wb_initial_stdev:       0.350     # rad/sec - initial bias 
+    ab_rate_stdev:          0.1       # m/s2/sqrt(s)           
+    wb_rate_stdev:          0.0400    # rad/s/sqrt(s)
diff --git a/include/imu/capture/capture_imu.h b/include/imu/capture/capture_imu.h
index 861af516e10a8c48afc1be766800cf8a7721cbc6..274d74d494ec4897e11360b4a25bd497098aa6bd 100644
--- a/include/imu/capture/capture_imu.h
+++ b/include/imu/capture/capture_imu.h
@@ -23,7 +23,7 @@ class CaptureImu : public CaptureMotion
                    SensorBasePtr _sensor_ptr,
                    const Eigen::Vector6d& _data,
                    const Eigen::MatrixXd& _data_cov,
-                   const Vector6d& _bias,
+                   const VectorXd& _bias,
                    CaptureBasePtr _capture_origin_ptr = nullptr);
 
         ~CaptureImu() override;
diff --git a/include/imu/factor/factor_imu2d.h b/include/imu/factor/factor_imu2d.h
new file mode 100644
index 0000000000000000000000000000000000000000..4e9be3689c49fbfedda19f69b3c1bf0139e1604c
--- /dev/null
+++ b/include/imu/factor/factor_imu2d.h
@@ -0,0 +1,184 @@
+#ifndef FACTOR_IMU2D_THETA_H_
+#define FACTOR_IMU2D_THETA_H_
+
+//Wolf includes
+#include "imu/feature/feature_imu2d.h"
+#include "imu/processor/processor_imu2d.h"
+#include "imu/sensor/sensor_imu2d.h"
+#include "core/factor/factor_autodiff.h"
+#include "core/math/rotations.h"
+#include "imu/math/imu2d_tools.h"
+
+//Eigen include
+
+namespace wolf {
+    
+WOLF_PTR_TYPEDEFS(FactorImu2d);
+
+//class
+class FactorImu2d : public FactorAutodiff<FactorImu2d, 8, 2, 1, 2, 3, 2, 1, 2, 3>
+{
+    public:
+        FactorImu2d(const FeatureImu2dPtr& _ftr_ptr,
+                    const CaptureImuPtr& _capture_origin_ptr,
+                    const ProcessorBasePtr& _processor_ptr,
+                    bool _apply_loss_function,
+                    FactorStatus _status = FAC_ACTIVE);
+
+        ~FactorImu2d() override = default;
+
+        /** \brief : compute the residual from the state blocks being iterated by the solver.
+            -> computes the expected measurement
+            -> corrects actual measurement with new bias
+            -> compares the corrected measurement with the expected one
+            -> weights the result with the covariance of the noise (residual = sqrt_info_matrix * err;)
+        */
+        template<typename T>
+        bool operator ()(const T* const _p1,
+                         const T* const _o1,
+                         const T* const _v1,
+                         const T* const _b1,
+                         const T* const _p2,
+                         const T* const _o2,
+                         const T* const _v2,
+                         const T* const _b2,
+                         T* _res) const;
+        Eigen::Matrix3d getBiasDriftSquareRootInformationUpper(const FeatureImu2dPtr& _ftr_ptr)
+        {
+            Eigen::Matrix3d res = Eigen::Matrix3d::Identity();
+            if(_ftr_ptr->getCapture()->getSensor()){
+              res *= 1./(std::static_pointer_cast<SensorImu2d>(_ftr_ptr->getCapture()->getSensor())->getAbRateStdev() * dt_);
+              res(2,2) = 1./(std::static_pointer_cast<SensorImu2d>(_ftr_ptr->getCapture()->getSensor())->getWbRateStdev() * dt_);
+            }
+            WOLF_WARN_COND(!_ftr_ptr->getCapture()->getSensor(), "Null Sensor Pointer");
+            return res;
+        }
+
+    private:
+        // Imu processor
+        ProcessorImu2dPtr processor_imu2d_;
+
+        /// Preintegrated delta
+        Eigen::Vector5d delta_preint_;
+
+        // Biases used during preintegration
+        Eigen::Vector3d bias_preint_;
+
+        // Jacobians of preintegrated deltas wrt biases
+        Eigen::Matrix<double, 5, 3> jacobian_bias_;
+
+        /// Metrics
+        const double dt_; ///< delta-time and delta-time-squared between keyframes
+        
+        /** bias covariance and bias residuals
+         *
+         * continuous bias covariance matrix for accelerometer would then be A_r = diag(ab_stdev_^2, ab_stdev_^2, ab_stdev_^2)
+         * To compute bias residuals, we will need to do (sqrt(A_r)).inverse() * ab_error
+         *
+         * In our case, we introduce time 'distance' in the computation of this residual (SEE FORSTER17), thus we have to use the discret covariance matrix
+         * discrete bias covariance matrix for accelerometer : A_r_dt = dt_ * A_r
+         * taking the square root for bias residuals : sqrt_A_r_dt = sqrt(dt_ * A_r) = sqrt(dt_) * sqrt(A_r)
+         * then with the inverse : sqrt_A_r_dt_inv = (sqrt(dt_ * A_r)).inverse() = (1/sqrt(dt_)) * sqrt(A_r).inverse()
+         *
+         * same logic for gyroscope bias
+         */ 
+        const Eigen::Matrix5d sqrt_delta_preint_inv_;
+        const Eigen::Matrix3d sqrt_bias_drift_dt_inv_;
+
+    public:
+      EIGEN_MAKE_ALIGNED_OPERATOR_NEW;
+};
+
+///////////////////// IMPLEMENTAITON ////////////////////////////
+
+inline FactorImu2d::FactorImu2d(const FeatureImu2dPtr&    _ftr_ptr,
+                                const CaptureImuPtr&    _cap_origin_ptr,
+                                const ProcessorBasePtr& _processor_ptr,
+                                bool                    _apply_loss_function,
+                                FactorStatus        _status) :
+                FactorAutodiff<FactorImu2d, 8, 2, 1, 2, 3, 2, 1, 2, 3>( // ...
+                        "FactorImu2d",
+                        TOP_MOTION,
+                        _ftr_ptr,
+                        _cap_origin_ptr->getFrame(),
+                        _cap_origin_ptr,
+                        nullptr,
+                        nullptr,
+                        _processor_ptr,
+                        _apply_loss_function,
+                        _status,
+                        _cap_origin_ptr->getFrame()->getP(),
+                        _cap_origin_ptr->getFrame()->getO(),
+                        _cap_origin_ptr->getFrame()->getV(),
+                        _cap_origin_ptr->getSensorIntrinsic(),
+                        _ftr_ptr->getFrame()->getP(),
+                        _ftr_ptr->getFrame()->getO(),
+                        _ftr_ptr->getFrame()->getV(),
+                        _ftr_ptr->getCapture()->getSensorIntrinsic()),
+        processor_imu2d_(std::static_pointer_cast<ProcessorImu2d>(_processor_ptr)),
+        delta_preint_(_ftr_ptr->getMeasurement()), // dp, dth, dv at preintegration time
+        bias_preint_(_ftr_ptr->getBiasPreint()), // state biases at preintegration time
+        jacobian_bias_(_ftr_ptr->getJacobianBias()), // Jacs of dp dv dq wrt biases
+        dt_(_ftr_ptr->getFrame()->getTimeStamp() - _cap_origin_ptr->getTimeStamp()),
+        sqrt_delta_preint_inv_(_ftr_ptr->getMeasurementSquareRootInformationUpper()),
+        sqrt_bias_drift_dt_inv_(getBiasDriftSquareRootInformationUpper(_ftr_ptr))
+{
+    //
+}
+
+template<typename T>
+inline bool FactorImu2d::operator ()(const T* const _p1,
+                                   const T* const _th1,
+                                   const T* const _v1,
+                                   const T* const _b1,
+                                   const T* const _p2,
+                                   const T* const _th2,
+                                   const T* const _v2,
+                                   const T* const _b2,
+                                   T* _res) const
+{
+    using namespace Eigen;
+
+    // MAPS
+    Map<const Matrix<T,2,1> > p1(_p1);
+    const T& th1              = *_th1;
+    Map<const Matrix<T,2,1> > v1(_v1);
+    Map<const Matrix<T,3,1> > b1(_b1);
+
+    Map<const Matrix<T,2,1> > p2(_p2);
+    const T& th2              = *_th2;
+    Map<const Matrix<T,2,1> > v2(_v2);
+    Map<const Matrix<T,3,1> > b2(_b2);
+
+    Map<Matrix<T,8,1> > res(_res);
+
+    //residual
+    /*
+     * MATH:
+     * res_delta = (Covariancia delta)^(T/2) * ((delta_preint (+) Jacob^delta_bias*(b1-b1_preint))- (x2 (-) x1)) 
+     */
+    Matrix<T, 5, 1> delta_step = jacobian_bias_*(b1 - bias_preint_);
+    Matrix<T, 5, 1> delta_preint = delta_preint_.cast<T>();
+    Matrix<T, 5, 1> delta_corr = imu2d::plus(delta_preint, delta_step);
+
+    Matrix<T, 5, 1> delta_predicted;
+    Map<Matrix<T,2,1> > dp_predicted( &delta_predicted(0) + 0);
+    T& dth_predicted = delta_predicted(2);
+    Map<Matrix<T,2,1> > dv_predicted(&delta_predicted(0) + 3);
+    imu2d::between(p1, th1, v1, p2, th2, v2, dt_, dp_predicted, dth_predicted, dv_predicted); 
+
+    Matrix<T, 5, 1> delta_error = delta_corr - delta_predicted;
+    delta_error(2) = pi2pi(delta_error(2));
+
+    res.template head<5>() = sqrt_delta_preint_inv_*delta_error;
+    
+
+    //bias drift
+    res.template tail<3>() = sqrt_bias_drift_dt_inv_*(b2 -b1);
+
+    return true;
+}
+
+} // namespace wolf
+
+#endif
diff --git a/include/imu/feature/feature_imu2d.h b/include/imu/feature/feature_imu2d.h
new file mode 100644
index 0000000000000000000000000000000000000000..713df8f8489fad8be3fe7d6fbf3988e61a44cb60
--- /dev/null
+++ b/include/imu/feature/feature_imu2d.h
@@ -0,0 +1,68 @@
+#ifndef FEATURE_IMU2D_H_
+#define FEATURE_IMU2D_H_
+
+//Wolf includes
+#include "imu/capture/capture_imu.h"
+#include "core/feature/feature_base.h"
+#include "core/common/wolf.h"
+
+//std includes
+
+namespace wolf {
+
+WOLF_PTR_TYPEDEFS(FeatureImu2d);
+
+class FeatureImu2d : public FeatureBase
+{
+    public:
+
+        /** \brief Constructor from and measures
+         *
+         * \param _measurement the measurement
+         * \param _meas_covariance the noise of the measurement
+         * \param _dD_db_jacobians Jacobians of preintegrated delta wrt Imu2d biases
+         * \param acc_bias accelerometer bias of origin frame
+         * \param gyro_bias gyroscope bias of origin frame
+         * \param _cap_imu_ptr pointer to parent CaptureMotion
+         */
+        FeatureImu2d(const Eigen::VectorXd& _delta_preintegrated,
+                   const Eigen::MatrixXd& _delta_preintegrated_covariance,
+                   const Eigen::Vector3d& _bias,
+                   const Eigen::Matrix<double,5,3>& _dD_db_jacobians,
+                   CaptureMotionPtr _cap_imu_ptr = nullptr);
+
+        /** \brief Constructor from capture pointer
+         *
+         * \param _cap_imu_ptr pointer to parent CaptureMotion
+         */
+        FeatureImu2d(CaptureMotionPtr _cap_imu_ptr);
+
+        ~FeatureImu2d() override;
+
+        const Eigen::Vector3d&              getBiasPreint()  const;
+        const Eigen::Matrix<double, 5, 3>&  getJacobianBias()   const;
+
+    private:
+
+        // Used biases
+        Eigen::Vector3d bias_preint_;       
+
+        Eigen::Matrix<double, 5, 3> jacobian_bias_;
+
+    public:
+      EIGEN_MAKE_ALIGNED_OPERATOR_NEW;
+};
+
+inline const Eigen::Vector3d& FeatureImu2d::getBiasPreint() const
+{
+    return bias_preint_;
+}
+
+inline const Eigen::Matrix<double, 5, 3>& FeatureImu2d::getJacobianBias() const
+{
+    return jacobian_bias_;
+}
+
+} // namespace wolf
+
+#endif
diff --git a/include/imu/math/imu2d_tools.h b/include/imu/math/imu2d_tools.h
new file mode 100644
index 0000000000000000000000000000000000000000..1abcd588f1354c7a7e0181dea8f602aba92ec390
--- /dev/null
+++ b/include/imu/math/imu2d_tools.h
@@ -0,0 +1,843 @@
+/*
+ * imu2d_tools.h
+ *
+ *  Created on: Nov 16, 2020
+ *      Author: igeer
+ */
+
+#ifndef IMU2D_TOOLS_H_
+#define IMU2D_TOOLS_H_
+
+#include "core/common/wolf.h"
+#include "core/math/rotations.h"
+#include "core/math/SE2.h"
+#include "core/state_block/state_composite.h"
+
+#include <cstdio>
+
+/*
+ * Most functions in this file are the 2d versions of the functions in imu_tools.h
+ * They relate manipulations of Delta motion magnitudes used for Imu pre-integration.
+ *
+ * The Delta is defined as
+ *     Delta = [Dp, Dth, Dv]
+ * with
+ *     Dp  : position delta
+ *     Dth : angle delta
+ *     Dv  : velocity delta
+ *
+ * They are listed below:
+ *
+ *   - identity: I = Delta at the origin, with Dp = [0,0]; Dth = [0], Dv = [0,0]
+ *   - inverse: so that D (+) D.inv = I
+ *   - compose: Dc = D1 (+) D2
+ *   - between: Db = D2 (-) D1, so that D2 = D1 (+) Db
+ *   - composeOverState: x2 = x1 (+) D
+ *   - betweenStates: D = x2 (-) x1, so that x2 = x1 (+) D
+ *   - log: go from Delta manifold to tangent space (equivalent to log() in rotations)
+ *   - exp_Imu: go from tangent space to delta manifold (equivalent to exp() in rotations)
+ *   - plus: D2 = D1 (+) exp_Imu(d)
+ *   - diff: d = log_Imu( D2 (-) D1 )
+ *   - body2delta: construct a delta from body magnitudes of linAcc and angVel
+ */
+
+namespace wolf 
+{
+namespace imu2d {
+using namespace Eigen;
+using namespace SE2;
+
+template<typename D1, typename D2, typename D3>
+inline void identity(MatrixBase<D1>& p, double& th, MatrixBase<D3>& v)
+{
+    p = MatrixBase<D1>::Zero(2,1);
+    th = 0;
+    v = MatrixBase<D3>::Zero(2,1);
+}
+
+template<typename D1, typename D2, typename D3>
+inline void identity(MatrixBase<D1>& p, MatrixBase<D2>& th, MatrixBase<D3>& v)
+{
+    typedef typename D1::Scalar T1;
+    typedef typename D2::Scalar T2;
+    typedef typename D3::Scalar T3;
+    p << T1(0), T1(0);
+    th << T2(0);
+    v << T3(0), T3(0);
+}
+
+template<typename T = double>
+inline Matrix<T, 5, 1> identity()
+{
+    Matrix<T, 5, 1> ret;
+    ret<< T(0), T(0),
+          T(0),
+          T(0), T(0);
+    return ret;
+}
+
+inline VectorComposite identityComposite()
+{
+    VectorComposite D;
+    D.emplace('P', Vector2d::Zero());
+    D.emplace('O', Vector1d::Zero());
+    D.emplace('V', Vector2d::Zero());
+    return D;
+}
+
+template<typename D1, typename D2, typename D3, typename D4, class T1, class T2, class T3>
+inline void inverse(const MatrixBase<D1>& dp, const T1& dth, const MatrixBase<D2>& dv,
+                    const T2& dt,
+                    MatrixBase<D3>& idp, T3& idth, MatrixBase<D4>& idv )
+{
+    MatrixSizeCheck<2, 1>::check(dp);
+    MatrixSizeCheck<2, 1>::check(dv);
+    MatrixSizeCheck<2, 1>::check(idp);
+    MatrixSizeCheck<2, 1>::check(idv);
+    const auto& dR1T = Eigen::Rotation2D<T1>(-dth).matrix();
+
+    idp  =  - dR1T*(dp - dv*dt );
+    idth =  - dth;
+    idv  =  - dR1T*dv;
+}
+
+template<typename D1, typename D2, class T>
+inline void inverse(const MatrixBase<D1>& d,
+                    T dt,
+                    MatrixBase<D2>& id)
+{
+    MatrixSizeCheck<5, 1>::check(d);
+    MatrixSizeCheck<5, 1>::check(id);
+
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dp   ( & d( 0 ) );
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dv   ( & d( 3 ) );
+    Map<Matrix<typename D2::Scalar, 2, 1> >         idp  ( & id( 0 ) );
+    Map<Matrix<typename D2::Scalar, 2, 1> >         idv  ( & id( 3 ) );
+
+    inverse(dp, d(2), dv, dt, idp, id(2), idv);
+}
+
+template<typename D, class T>
+inline Matrix<typename D::Scalar, 5, 1> inverse(const MatrixBase<D>& d,
+                                                 T& dt)
+{
+    Matrix<typename D::Scalar, 5, 1> id;
+    inverse(d, dt, id);
+    return id;
+}
+
+template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6, class T1, class T2, class T3, class T4>
+inline void compose(const MatrixBase<D1>& dp1, const T1& dth1, const MatrixBase<D2>& dv1,
+                    const MatrixBase<D3>& dp2, const T2& dth2, const MatrixBase<D4>& dv2,
+                    const T3& dt,
+                    MatrixBase<D5>& sum_p, T4& sum_th, MatrixBase<D6>& sum_v )
+{
+        MatrixSizeCheck<2, 1>::check(dp1);
+        MatrixSizeCheck<2, 1>::check(dv1);
+        MatrixSizeCheck<2, 1>::check(dp2);
+        MatrixSizeCheck<2, 1>::check(dv2);
+        MatrixSizeCheck<2, 1>::check(sum_p);
+        MatrixSizeCheck<2, 1>::check(sum_v);
+        const auto& dR1 = Eigen::Rotation2D<T1>(dth1).matrix();
+
+        sum_p  = dp1 + dv1*dt +         dR1*dp2;  //Rotation matrix here and below because we are rotating a vector
+        sum_v  = dv1 +                  dR1*dv2;
+        sum_th =               pi2pi(dth1+dth2);  //Sum here because angles compose by sum
+}
+
+template<typename D1, typename D2, typename D3, class T>
+inline void compose(const MatrixBase<D1>& d1,
+                    const MatrixBase<D2>& d2,
+                    T dt,
+                    MatrixBase<D3>& sum)
+{
+    MatrixSizeCheck<5, 1>::check(d1);
+    MatrixSizeCheck<5, 1>::check(d2);
+    MatrixSizeCheck<5, 1>::check(sum);
+
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dp1    ( & d1( 0 ) );
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dv1    ( & d1( 3 ) );
+    Map<const Matrix<typename D2::Scalar, 2, 1> >   dp2    ( & d2( 0 ) );
+    Map<const Matrix<typename D2::Scalar, 2, 1> >   dv2    ( & d2( 3 ) );
+    Map<Matrix<typename D3::Scalar, 2, 1> >         sum_p  ( & sum( 0 ) );
+    sum(2)                                          =       d1(2) + d2(2);
+    Map<Matrix<typename D3::Scalar, 2, 1> >         sum_v  ( & sum( 3 ) );
+
+    compose(dp1, d1(2), dv1, dp2, d2(2), dv2, dt, sum_p, sum(2), sum_v);
+}
+
+inline void compose(const VectorComposite& d1, const VectorComposite& d2, double dt, VectorComposite& dc)
+{
+    compose(d1.at('P'), d1.at('O')(0), d1.at('V'), d2.at('P'), d2.at('O')(0), d2.at('V'), dt, dc['P'], dc['O'](0), dc['V']);
+}
+
+inline VectorComposite compose(const VectorComposite& d1, const VectorComposite& d2, double dt)
+{
+    VectorComposite dc("POV", {2,1,2});
+    compose(d1.at('P'), d1.at('O')(0), d1.at('V'), d2.at('P'), d2.at('O')(0), d2.at('V'), dt, dc['P'], dc['O'](0), dc['V']);
+    return dc;
+}
+
+template<typename D1, typename D2, class T>
+inline Matrix<typename D1::Scalar, 5, 1> compose(const MatrixBase<D1>& d1,
+                                                  const MatrixBase<D2>& d2,
+                                                  T dt)
+{
+    Matrix<typename D1::Scalar, 5, 1>  ret;
+    compose(d1, d2, dt, ret);
+    return ret;
+}
+
+template<typename D1, typename D2, typename D3, typename D4, typename D5, class T>
+inline void compose(const MatrixBase<D1>& d1,
+                    const MatrixBase<D2>& d2,
+                    T dt,
+                    MatrixBase<D3>& sum,
+                    MatrixBase<D4>& J_sum_d1,
+                    MatrixBase<D5>& J_sum_d2)
+{
+    MatrixSizeCheck<5, 1>::check(d1);
+    MatrixSizeCheck<5, 1>::check(d2);
+    MatrixSizeCheck<5, 1>::check(sum);
+    MatrixSizeCheck< 5, 5>::check(J_sum_d1);
+    MatrixSizeCheck< 5, 5>::check(J_sum_d2);
+
+    //Useful auxiliaries
+    const auto& dR1 = Rotation2D<typename D1::Scalar>(d1(2)).matrix();
+
+    // Jac wrt first delta
+    J_sum_d1.setIdentity();                                             // dDp'/dDp = dDv'/dDv = I
+    J_sum_d1.block(0,2,2,1).noalias() =  dR1 * skewed(d2.head(2)) ;     // dDp'/dDo
+    J_sum_d1.block(0,3,2,2).noalias() = Matrix2d::Identity() * dt;                // dDp'/dDv = I*dt
+    J_sum_d1.block(3,2,2,1).noalias() =  dR1 * skewed(d2.tail(2)) ;     // dDv'/dDo
+    // J_sum_d1.block(2,2,1,1) = 1;                                     // dDo'/dDo = 1
+
+    // Jac wrt second delta
+    J_sum_d2.setIdentity();                                     //
+    J_sum_d2.block(0,0,2,2) = dR1;                              // dDp'/ddp
+    J_sum_d2.block(3,3,2,2) = dR1;                              // dDv'/ddv
+    // J_sum_d2.block(2,2,1,1) = 1;                             // dDo'/ddo = 1
+
+    // compose deltas -- done here to avoid aliasing when calling with input `d1` and result `sum` referencing the same variable
+    compose(d1, d2, dt, sum);
+}
+
+//inline void compose(const VectorComposite& d1,
+//                    const VectorComposite& d2,
+//                    double dt,
+//                    VectorComposite& sum,
+//                    MatrixComposite& J_sum_d1,
+//                    MatrixComposite& J_sum_d2)
+//{
+//
+//    // Some useful temporaries
+//    Matrix3d dR1 = q2R(d1.at('O')); //dq1.matrix(); // First  Delta, DR
+//    Matrix3d dR2 = q2R(d2.at('O')); //dq2.matrix(); // Second delta, dR
+//
+//    // Jac wrt first delta // TODO find optimal way to re-use memory allocation!!!
+//    J_sum_d1.clear();
+//    J_sum_d1.emplace('P','P', Matrix3d::Identity());        // dDp'/dDp = I
+//    J_sum_d1.emplace('P','O', - dR1 * skew(d2.at('P'))) ;   // dDp'/dDo
+//    J_sum_d1.emplace('P','V', Matrix3d::Identity() * dt);   // dDp'/dDv = I*dt
+//    J_sum_d1.emplace('O','P', Matrix3d::Zero());
+//    J_sum_d1.emplace('O','O', dR2.transpose());             // dDo'/dDo
+//    J_sum_d1.emplace('O','V', Matrix3d::Zero());
+//    J_sum_d1.emplace('V','P', Matrix3d::Zero());
+//    J_sum_d1.emplace('V','O', - dR1 * skew(d2.at('V'))) ;   // dDv'/dDo
+//    J_sum_d1.emplace('V','V', Matrix3d::Identity());        // dDv'/dDv = I
+//
+//
+//    // Jac wrt second delta
+//    J_sum_d2.clear();
+//    J_sum_d2.emplace('P','P', dR1);                 // dDp'/ddp
+//    J_sum_d2.emplace('P','O', Matrix3d::Zero()) ;   // dDp'/ddo
+//    J_sum_d2.emplace('P','V', Matrix3d::Zero());    // dDp'/ddv
+//    J_sum_d2.emplace('O','P', Matrix3d::Zero());
+//    J_sum_d2.emplace('O','O', Matrix3d::Identity());// dDo'/ddo
+//    J_sum_d2.emplace('O','V', Matrix3d::Zero());
+//    J_sum_d2.emplace('V','P', Matrix3d::Zero());
+//    J_sum_d2.emplace('V','O', Matrix3d::Zero()) ;   // dDv'/ddo
+//    J_sum_d2.emplace('V','V', dR1);                 // dDv'/ddv
+//
+//    // compose deltas -- done here to avoid aliasing when calling with input `d1` and result `sum` referencing the same variable
+//    compose(d1, d2, dt, sum);
+//}
+//
+template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6, class T1, class T2, class T3, class T4>
+inline void between(const MatrixBase<D1>& dp1, const T1& dth1, const MatrixBase<D2>& dv1,
+                    const MatrixBase<D3>& dp2, const T2& dth2, const MatrixBase<D4>& dv2,
+                    const T3 dt,
+                    MatrixBase<D5>& diff_p, T4& diff_th, MatrixBase<D6>& diff_v )
+{
+        MatrixSizeCheck<2, 1>::check(dp1);
+        MatrixSizeCheck<2, 1>::check(dv1);
+        MatrixSizeCheck<2, 1>::check(dp2);
+        MatrixSizeCheck<2, 1>::check(dv2);
+        MatrixSizeCheck<2, 1>::check(diff_p);
+        MatrixSizeCheck<2, 1>::check(diff_v);
+
+        const auto& dR1_tr = Rotation2D<T1>(-dth1).matrix();
+        diff_p = dR1_tr * ( dp2 - dp1 - dv1*dt );
+        diff_v = dR1_tr * ( dv2 - dv1 );
+        diff_th = pi2pi(dth2  -   dth1);
+}
+
+template<typename D1, typename D2, typename D3, class T>
+inline void between(const MatrixBase<D1>& d1,
+                    const MatrixBase<D2>& d2,
+                    T dt,
+                    MatrixBase<D3>& d2_minus_d1)
+{
+    MatrixSizeCheck<5, 1>::check(d1);
+    MatrixSizeCheck<5, 1>::check(d2);
+    MatrixSizeCheck<5, 1>::check(d2_minus_d1);
+
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dp1    ( & d1(0) );
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dv1    ( & d1(3) );
+    Map<const Matrix<typename D2::Scalar, 2, 1> >   dp2    ( & d2(0) );
+    Map<const Matrix<typename D2::Scalar, 2, 1> >   dv2    ( & d2(3) );
+    Map<Matrix<typename D3::Scalar, 2, 1> >         diff_p ( & d2_minus_d1(0) );
+    Map<Matrix<typename D3::Scalar, 2, 1> >         diff_v ( & d2_minus_d1(3) );
+
+    between(dp1, d1(2), dv1, dp2, d2(2), dv2, dt, diff_p, d2_minus_d1(2), diff_v);
+}
+
+template<typename D1, typename D2, class T>
+inline Matrix<typename D1::Scalar, 5, 1> between(const MatrixBase<D1>& d1,
+                                                  const MatrixBase<D2>& d2,
+                                                  T dt)
+{
+    Matrix<typename D1::Scalar, 5, 1> diff;
+    between(d1, d2, dt, diff);
+    return diff;
+}
+
+//template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6, typename D7, typename D8, typename D9, class T>
+//inline void composeOverState(const MatrixBase<D1>& p, const QuaternionBase<D2>& q, const MatrixBase<D3>& v,
+//                             const MatrixBase<D4>& dp,const QuaternionBase<D5>& dq,const MatrixBase<D6>& dv,
+//                             T dt,
+//                             MatrixBase<D7>& p_plus_dp, QuaternionBase<D8>& q_plus_dq, MatrixBase<D9>& v_plus_dv)
+//{
+//    MatrixSizeCheck<3, 1>::check(p);
+//    MatrixSizeCheck<3, 1>::check(v);
+//    MatrixSizeCheck<3, 1>::check(dp);
+//    MatrixSizeCheck<3, 1>::check(dv);
+//    MatrixSizeCheck<3, 1>::check(p_plus_dp);
+//    MatrixSizeCheck<3, 1>::check(v_plus_dv);
+//
+//    p_plus_dp = p + v*dt + 0.5*gravity()*dt*dt + q*dp;
+//    v_plus_dv = v +            gravity()*dt    + q*dv;
+//    q_plus_dq =                                  q*dq; // dq here to avoid possible aliasing between x and x_plus_d
+//}
+//
+//template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6, typename D7, typename D8, typename D9, class T>
+//inline void composeOverState(const MatrixBase<D1>& p ,  const MatrixBase<D2>& q ,  const MatrixBase<D3>& v,
+//                             const MatrixBase<D4>& dp,  const MatrixBase<D5>& dq,  const MatrixBase<D6>& dv,
+//                             T dt,
+//                             MatrixBase<D7>& p_plus_dp, MatrixBase<D8>& q_plus_dq, MatrixBase<D9>& v_plus_dv)
+//{
+//
+//        MatrixSizeCheck<3, 1>::check(p);
+//        MatrixSizeCheck<4, 1>::check(q);
+//        MatrixSizeCheck<3, 1>::check(v);
+//        MatrixSizeCheck<3, 1>::check(dp);
+//        MatrixSizeCheck<4, 1>::check(dq);
+//        MatrixSizeCheck<3, 1>::check(dv);
+//        MatrixSizeCheck<3, 1>::check(p_plus_dp);
+//        MatrixSizeCheck<4, 1>::check(q_plus_dq);
+//        MatrixSizeCheck<3, 1>::check(v_plus_dv);
+//
+//        Map<const Quaternion<typename D2::Scalar> > qq           ( & q           (0) );
+//        Map<const Quaternion<typename D5::Scalar> > dqq          ( & dq          (0) );
+//        Map<      Quaternion<typename D8::Scalar> > qq_plus_dqq  ( & q_plus_dq   (0) );
+//
+//        composeOverState(p,  qq,  v,
+//                         dp, dqq, dv,
+//                         dt,
+//                         p_plus_dp, qq_plus_dqq, v_plus_dv);
+//}
+//
+//template<typename D1, typename D2, typename D3, class T>
+//inline void composeOverState(const MatrixBase<D1>& x,
+//                             const MatrixBase<D2>& d,
+//                             T dt,
+//                             MatrixBase<D3>& x_plus_d)
+//{
+//    MatrixSizeCheck<10, 1>::check(x);
+//    MatrixSizeCheck<10, 1>::check(d);
+//    MatrixSizeCheck<10, 1>::check(x_plus_d);
+//
+//    Map<const Matrix<typename D1::Scalar, 3, 1> >   p         ( & x( 0 ) );
+//    Map<const Quaternion<typename D1::Scalar> >     q         ( & x( 3 ) );
+//    Map<const Matrix<typename D1::Scalar, 3, 1> >   v         ( & x( 7 ) );
+//    Map<const Matrix<typename D2::Scalar, 3, 1> >   dp        ( & d( 0 ) );
+//    Map<const Quaternion<typename D2::Scalar> >     dq        ( & d( 3 ) );
+//    Map<const Matrix<typename D2::Scalar, 3, 1> >   dv        ( & d( 7 ) );
+//    Map<Matrix<typename D3::Scalar, 3, 1> >         p_plus_d  ( & x_plus_d( 0 ) );
+//    Map<Quaternion<typename D3::Scalar> >           q_plus_d  ( & x_plus_d( 3 ) );
+//    Map<Matrix<typename D3::Scalar, 3, 1> >         v_plus_d  ( & x_plus_d( 7 ) );
+//
+//    composeOverState( p,  q,  v,
+//                     dp, dq, dv,
+//                     dt,
+//                     p_plus_d, q_plus_d, v_plus_d);
+//}
+//
+//template<typename D1, typename D2, class T>
+//inline Matrix<typename D1::Scalar, 10, 1> composeOverState(const MatrixBase<D1>& x,
+//                                                           const MatrixBase<D2>& d,
+//                                                           T dt)
+//{
+//    Matrix<typename D1::Scalar, 10, 1>  ret;
+//    composeOverState(x, d, dt, ret);
+//    return ret;
+//}
+//
+//template<class T>
+//inline void composeOverState(const VectorComposite& x,
+//                             const VectorComposite& d,
+//                             T dt,
+//                             VectorComposite& x_plus_d)
+//{
+//        assert(x_plus_d.count('P') && "provided reference does not have key 'P'");
+//        assert(x_plus_d.count('O') && "provided reference does not have key 'O'");
+//        assert(x_plus_d.count('V') && "provided reference does not have key 'V'");
+//
+//        composeOverState(x.at('P'), x.at('O'), x.at('V'),
+//                         d.at('P'), d.at('O'), d.at('V'),
+//                         dt,
+//                         x_plus_d['P'], x_plus_d['O'], x_plus_d['V']);
+//}
+//
+//template<class T>
+//inline VectorComposite composeOverState(const VectorComposite& x,
+//                                        const VectorComposite& d,
+//                                        T dt)
+//{
+//    VectorComposite  ret("POV", {3,4,3});
+//
+//    composeOverState(x, d, dt, ret);
+//    return ret;
+//}
+//
+//template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6, typename D7, typename D8, typename D9, class T>
+//inline void betweenStates(const MatrixBase<D1>& p1, const QuaternionBase<D2>& q1, const MatrixBase<D3>& v1,
+//                          const MatrixBase<D4>& p2, const QuaternionBase<D5>& q2, const MatrixBase<D6>& v2,
+//                          const T dt,
+//                          MatrixBase<D7>& dp, QuaternionBase<D8>& dq, MatrixBase<D9>& dv )
+//{
+//        MatrixSizeCheck<3, 1>::check(p1);
+//        MatrixSizeCheck<3, 1>::check(v1);
+//        MatrixSizeCheck<3, 1>::check(p2);
+//        MatrixSizeCheck<3, 1>::check(v2);
+//        MatrixSizeCheck<3, 1>::check(dp);
+//        MatrixSizeCheck<3, 1>::check(dv);
+//
+//        dp = q1.conjugate() * ( p2 - p1 - v1*dt - (T)0.5*gravity().cast<T>()*(T)dt*(T)dt );
+//        dv = q1.conjugate() * ( v2 - v1         -     gravity().cast<T>()*(T)dt );
+//        dq = q1.conjugate() *   q2;
+//}
+//
+//template<typename D1, typename D2, typename D3, class T>
+//inline void betweenStates(const MatrixBase<D1>& x1,
+//                          const MatrixBase<D2>& x2,
+//                          T dt,
+//                          MatrixBase<D3>& x2_minus_x1)
+//{
+//    MatrixSizeCheck<10, 1>::check(x1);
+//    MatrixSizeCheck<10, 1>::check(x2);
+//    MatrixSizeCheck<10, 1>::check(x2_minus_x1);
+//
+//    Map<const Matrix<typename D1::Scalar, 3, 1> >   p1  ( & x1(0) );
+//    Map<const Quaternion<typename D1::Scalar> >     q1  ( & x1(3) );
+//    Map<const Matrix<typename D1::Scalar, 3, 1> >   v1  ( & x1(7) );
+//    Map<const Matrix<typename D2::Scalar, 3, 1> >   p2  ( & x2(0) );
+//    Map<const Quaternion<typename D2::Scalar> >     q2  ( & x2(3) );
+//    Map<const Matrix<typename D2::Scalar, 3, 1> >   v2  ( & x2(7) );
+//    Map<Matrix<typename D3::Scalar, 3, 1> >         dp  ( & x2_minus_x1(0) );
+//    Map<Quaternion<typename D3::Scalar> >           dq  ( & x2_minus_x1(3) );
+//    Map<Matrix<typename D3::Scalar, 3, 1> >         dv  ( & x2_minus_x1(7) );
+//
+//    betweenStates(p1, q1, v1, p2, q2, v2, dt, dp, dq, dv);
+//}
+//
+//template<typename D1, typename D2, class T>
+//inline Matrix<typename D1::Scalar, 10, 1> betweenStates(const MatrixBase<D1>& x1,
+//                                                        const MatrixBase<D2>& x2,
+//                                                        T dt)
+//{
+//    Matrix<typename D1::Scalar, 10, 1> ret;
+//    betweenStates(x1, x2, dt, ret);
+//    return ret;
+//}
+//
+//template<typename Derived>
+//Matrix<typename Derived::Scalar, 9, 1> log_Imu(const MatrixBase<Derived>& delta_in)
+//{
+//    MatrixSizeCheck<10, 1>::check(delta_in);
+//
+//    Matrix<typename Derived::Scalar, 9, 1> ret;
+//
+//    Map<const Matrix<typename Derived::Scalar, 3, 1> >   dp_in  ( & delta_in(0) );
+//    Map<const Quaternion<typename Derived::Scalar> >     dq_in  ( & delta_in(3) );
+//    Map<const Matrix<typename Derived::Scalar, 3, 1> >   dv_in  ( & delta_in(7) );
+//    Map<Matrix<typename Derived::Scalar, 3, 1> >         dp_ret ( & ret(0) );
+//    Map<Matrix<typename Derived::Scalar, 3, 1> >         do_ret ( & ret(3) );
+//    Map<Matrix<typename Derived::Scalar, 3, 1> >         dv_ret ( & ret(6) );
+//
+//    dp_ret = dp_in;
+//    dv_ret = dv_in;
+//    do_ret = log_q(dq_in);
+//
+//    return ret;
+//}
+//
+//template<typename Derived>
+//Matrix<typename Derived::Scalar, 10, 1> exp_Imu(const MatrixBase<Derived>& d_in)
+//{
+//    MatrixSizeCheck<9, 1>::check(d_in);
+//
+//    Matrix<typename Derived::Scalar, 10, 1> ret;
+//
+//    Map<const Matrix<typename Derived::Scalar, 3, 1> >   dp_in  ( & d_in(0) );
+//    Map<const Matrix<typename Derived::Scalar, 3, 1> >   do_in  ( & d_in(3) );
+//    Map<const Matrix<typename Derived::Scalar, 3, 1> >   dv_in  ( & d_in(6) );
+//    Map<Matrix<typename Derived::Scalar, 3, 1> >         dp     ( &  ret(0) );
+//    Map<Quaternion<typename Derived::Scalar> >           dq     ( &  ret(3) );
+//    Map<Matrix<typename Derived::Scalar, 3, 1> >         dv     ( &  ret(7) );
+//
+//    dp = dp_in;
+//    dv = dv_in;
+//    dq = exp_q(do_in);
+//
+//    return ret;
+//}
+//
+template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6, class T1, class T2, class T3>
+inline void plus(const MatrixBase<D1>& dp1, const T1& dth1, const MatrixBase<D2>& dv1,
+                 const MatrixBase<D3>& dp2, const T2& dth2, const MatrixBase<D4>& dv2,
+                 MatrixBase<D5>& plus_p, T3& plus_th, MatrixBase<D6>& plus_v )
+{
+        plus_p = dp1 + dp2;
+        plus_v = dv1 + dv2;
+        plus_th = dth1 + dth2;
+}
+
+template<typename D1, typename D2, typename D3>
+inline void plus(const MatrixBase<D1>& d1,
+                 const MatrixBase<D2>& d2,
+                 MatrixBase<D3>& d_pert)
+{
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dp1    ( & d1(0) );
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dv1    ( & d1(3) );
+    Map<const Matrix<typename D2::Scalar, 2, 1> >   dp2    ( & d2(0) );
+    Map<const Matrix<typename D2::Scalar, 2, 1> >   dv2    ( & d2(3) );
+    Map<Matrix<typename D3::Scalar, 2, 1> >         dp_p ( & d_pert(0) );
+    Map<Matrix<typename D3::Scalar, 2, 1> >         dv_p ( & d_pert(3) );
+
+    plus(dp1, d1(2), dv1, dp2, d2(2), dv2, dp_p, d_pert(2), dv_p);
+}
+
+template<typename D1, typename D2>
+inline Matrix<typename D1::Scalar, 5, 1> plus(const MatrixBase<D1>& d1,
+                                               const MatrixBase<D2>& d2)
+{
+    Matrix<typename D1::Scalar, 5, 1> ret;
+    plus(d1, d2, ret);
+    return ret;
+}
+//
+//inline void plus(const VectorComposite& x, const VectorComposite& tau, VectorComposite& res)
+//{
+//    plus(x.at('P'), x.at('O'), x.at('V'), tau.at('P'), tau.at('O'), tau.at('V'), res.at('P'), res.at('O'), res.at('V'));
+//}
+//
+//inline VectorComposite plus(const VectorComposite& x, const VectorComposite& tau)
+//{
+//    VectorComposite res("POV", {3,4,3});
+//
+//    plus(x, tau, res);
+//
+//    return res;
+//}
+
+
+template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6>
+inline void diff(const MatrixBase<D1>& dp1, const typename D1::Scalar& do1, const MatrixBase<D2>& dv1,
+                 const MatrixBase<D3>& dp2, const typename D1::Scalar& do2, const MatrixBase<D4>& dv2,
+                 MatrixBase<D5>& diff_p, typename D1::Scalar& diff_o, MatrixBase<D6>& diff_v )
+{
+        diff_p = dp2 - dp1;
+        diff_v = dv2 - dv1;
+        diff_o = do2 - do1;
+}
+
+//template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6, typename D7, typename D8, typename D9, typename D10, typename D11>
+//inline void diff(const MatrixBase<D1>& dp1, const QuaternionBase<D2>& dq1, const MatrixBase<D3>& dv1,
+//                 const MatrixBase<D4>& dp2, const QuaternionBase<D5>& dq2, const MatrixBase<D6>& dv2,
+//                 MatrixBase<D7>& diff_p, MatrixBase<D8>& diff_o, MatrixBase<D9>& diff_v ,
+//                 MatrixBase<D10>& J_do_dq1, MatrixBase<D11>& J_do_dq2)
+//{
+//    diff(dp1, dq1, dv1, dp2, dq2, dv2, diff_p, diff_o, diff_v);
+//
+//    J_do_dq1    = - jac_SO3_left_inv(diff_o);
+//    J_do_dq2    =   jac_SO3_right_inv(diff_o);
+//}
+
+template<typename D1, typename D2, typename D3>
+inline void diff(const MatrixBase<D1>& d1,
+                 const MatrixBase<D2>& d2,
+                 MatrixBase<D3>& err)
+{
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dp1    ( & d1(0) );
+    Map<const Matrix<typename D1::Scalar, 2, 1> >   dv1    ( & d1(3) );
+    Map<const Matrix<typename D2::Scalar, 2, 1> >   dp2    ( & d2(0) );
+    Map<const Matrix<typename D2::Scalar, 2, 1> >   dv2    ( & d2(3) );
+    Map<Matrix<typename D3::Scalar, 2, 1> >         diff_p ( & err(0) );
+    Map<Matrix<typename D3::Scalar, 2, 1> >         diff_v ( & err(3) );
+
+    diff(dp1, d1(2), dv1, dp2, d2(2), dv2, diff_p, err(2), diff_v);
+}
+
+//template<typename D1, typename D2, typename D3, typename D4, typename D5>
+//inline void diff(const MatrixBase<D1>& d1,
+//                 const MatrixBase<D2>& d2,
+//                 MatrixBase<D3>& dif,
+//                 MatrixBase<D4>& J_diff_d1,
+//                 MatrixBase<D5>& J_diff_d2)
+//{
+//    Map<const Matrix<typename D1::Scalar, 3, 1> >   dp1    ( & d1(0) );
+//    Map<const Quaternion<typename D1::Scalar> >     dq1    ( & d1(3) );
+//    Map<const Matrix<typename D1::Scalar, 3, 1> >   dv1    ( & d1(7) );
+//    Map<const Matrix<typename D2::Scalar, 3, 1> >   dp2    ( & d2(0) );
+//    Map<const Quaternion<typename D2::Scalar> >     dq2    ( & d2(3) );
+//    Map<const Matrix<typename D2::Scalar, 3, 1> >   dv2    ( & d2(7) );
+//    Map<Matrix<typename D3::Scalar, 3, 1> >         diff_p ( & dif(0) );
+//    Map<Matrix<typename D3::Scalar, 3, 1> >         diff_o ( & dif(3) );
+//    Map<Matrix<typename D3::Scalar, 3, 1> >         diff_v ( & dif(6) );
+//
+//    Matrix<typename D4::Scalar, 3, 3> J_do_dq1, J_do_dq2;
+//
+//    diff(dp1, dq1, dv1, dp2, dq2, dv2, diff_p, diff_o, diff_v, J_do_dq1, J_do_dq2);
+//
+//    /* d = diff(d1, d2) is
+//     *   dp = dp2 - dp1
+//     *   do = Log(dq1.conj * dq2)
+//     *   dv = dv2 - dv1
+//     *
+//     * With trivial Jacobians for dp and dv, and:
+//     *   J_do_dq1 = - J_l_inv(theta)
+//     *   J_do_dq2 =   J_r_inv(theta)
+//     */
+//
+//    J_diff_d1 = - Matrix<typename D4::Scalar, 9, 9>::Identity();// d(p2  - p1) / d(p1) = - Identity
+//    J_diff_d1.block(3,3,3,3) = J_do_dq1;       // d(R1.tr*R2) / d(R1) = - J_l_inv(theta)
+//
+//    J_diff_d2.setIdentity();                                    // d(R1.tr*R2) / d(R2) =   Identity
+//    J_diff_d2.block(3,3,3,3) = J_do_dq2;      // d(R1.tr*R2) / d(R1) =   J_r_inv(theta)
+//}
+
+template<typename D1, typename D2>
+inline Matrix<typename D1::Scalar, 5, 1> diff(const MatrixBase<D1>& d1,
+                                              const MatrixBase<D2>& d2)
+{
+    Matrix<typename D1::Scalar, 5, 1> ret;
+    diff(d1, d2, ret);
+    return ret;
+}
+
+template<typename D1, typename D2, typename D3>
+inline void exp(const MatrixBase<D1>& a,
+                       const typename D1::Scalar& w,
+                       const typename D1::Scalar& dt,
+                       MatrixBase<D2>& dp,
+                       typename D1::Scalar& dth,
+                       MatrixBase<D3>& dv)
+{
+    MatrixSizeCheck<2,1>::check(a);
+    MatrixSizeCheck<2,1>::check(dp);
+    MatrixSizeCheck<2,1>::check(dv);
+
+    typedef typename D1::Scalar T;
+    dth = w*dt;
+    if(dth > Constants::EPS){
+      T s = std::sin(dth);
+      T c = std::cos(dth);
+      T aux1 = s/dth;
+      T aux2 = (1-c)/dth;
+      T aux3 = aux2/dth;
+      T aux4 = (dth-s)/(dth*dth);
+      Matrix<T,2,2> skw = SE2::skew((T) 1.0);
+
+      Matrix<T, 2, 2> P = Matrix<T, 2, 2>::Identity() * aux3 + skw*aux4;
+      Matrix<T, 2, 2> Q = Matrix<T, 2, 2>::Identity() * aux1 + skw*aux2;
+
+      dp = P*a*dt*dt;
+      dv = Q*a*dt;
+      //dth = dth;
+    }
+    else{
+      dp = (T)0.5*a*dt*dt;
+      dv = a*dt;
+      //dth = dth;
+    }
+}
+
+
+template<typename D1, typename D2, typename D3>
+inline void body2delta(const MatrixBase<D1>& a,
+                       const typename D1::Scalar& w,
+                       const typename D1::Scalar& dt,
+                       MatrixBase<D2>& dp,
+                       typename D1::Scalar& dth,
+                       MatrixBase<D3>& dv)
+{
+    MatrixSizeCheck<2,1>::check(a);
+    MatrixSizeCheck<2,1>::check(dp);
+    MatrixSizeCheck<2,1>::check(dv);
+
+    //dp = 0.5 * a * dt * dt;
+    //dv =       a * dt;
+    //dth = w * dt;
+    imu2d::exp(a, w, dt, dp, dth, dv);
+
+}
+
+//template<typename D1, typename D2, typename D3, typename D4, typename D5>
+//inline void body2delta(const MatrixBase<D1>& a,
+//                       const MatrixBase<D2>& w,
+//                       const typename D1::Scalar& dt,
+//                       MatrixBase<D3>& dp,
+//                       MatrixBase<D4>& dq,
+//                       MatrixBase<D5>& dv)
+//{
+//    MatrixSizeCheck<3,1>::check(a);
+//    MatrixSizeCheck<3,1>::check(w);
+//    MatrixSizeCheck<3,1>::check(dp);
+//    MatrixSizeCheck<4,1>::check(dq);
+//    MatrixSizeCheck<3,1>::check(dv);
+//
+//    Map<Quaternion<typename D4::Scalar>> mdq ( & dq(0) );
+//
+//    body2delta(a, w, dt, dp, mdq, dv);
+//}
+
+template<typename D1>
+inline Matrix<typename D1::Scalar, 5, 1> body2delta(const MatrixBase<D1>& body,
+                                                     const typename D1::Scalar& dt)
+{
+    MatrixSizeCheck<3,1>::check(body);
+
+    typedef typename D1::Scalar T;
+
+    Matrix<T, 5, 1> delta;
+
+    Map< Matrix<T, 2, 1>> dp ( & delta(0) );
+    Map< Matrix<T, 2, 1>> dv ( & delta(3) );
+
+    body2delta(body.block(0,0,2,1), body(2,0), dt, dp, delta(2), dv);
+
+    return delta;
+}
+
+//template<typename D1>
+//inline void body2delta(const MatrixBase<D1>& body,
+//                       const typename D1::Scalar& dt,
+//                       VectorComposite& _delta)
+//{
+//    MatrixSizeCheck<6,1>::check(body);
+//
+//    body2delta(body.block(0,0,3,1),
+//               body.block(3,0,3,1),
+//               dt,
+//               _delta['P'],
+//               _delta['O'],
+//               _delta['V']);
+//}
+
+template<typename D1, typename D2, typename D3>
+inline void body2delta(const MatrixBase<D1>& body,
+                       const typename D1::Scalar& dt,
+                       MatrixBase<D2>& delta,
+                       MatrixBase<D3>& jac_body)
+{
+    MatrixSizeCheck<3,1>::check(body);
+    MatrixSizeCheck<5,3>::check(jac_body);
+
+    typedef typename D1::Scalar T;
+
+    delta = body2delta(body, dt);
+
+    //Jacobians are not exact, we don't know the exact expression for the imu2d::exp() function
+    jac_body.setZero();
+    jac_body.block(0,0,2,2) = 0.5 * dt * dt * Matrix<T, 2, 2>::Identity();
+    jac_body(2,2)           =            dt;
+    jac_body.block(3,0,2,2) =            dt * Matrix<T, 2, 2>::Identity();
+}
+
+//template<typename D1>
+//inline void body2delta(const MatrixBase<D1>& body,
+//                       const typename D1::Scalar& dt,
+//                       VectorComposite& delta,
+//                       MatrixComposite& jac_body)
+//{
+//    MatrixSizeCheck<6,1>::check(body);
+//
+//    typedef typename D1::Scalar T;
+//
+//    body2delta(body, dt, delta);
+//
+//    Matrix<T, 3, 1> w = body.block(3,0,3,1);
+//
+//    jac_body.emplace('P','a', 0.5 * dt * dt * Matrix3d::Identity());    // 0,0
+//    jac_body.emplace('P','w',                 Matrix3d::Zero());        // 0,3
+//    jac_body.emplace('O','a',                 Matrix3d::Zero());        // 3,0
+//    jac_body.emplace('O','w',            dt * jac_SO3_right(w * dt));   // 3,3
+//    jac_body.emplace('V','a',            dt * Matrix3d::Identity());    // 6,0
+//    jac_body.emplace('V','w',                 Matrix3d::Zero());        // 6,6
+//}
+//template<typename D1, typename D2, typename D3, typename D4, typename D5, typename D6, typename D7>
+//void motion2data(const MatrixBase<D1>& a, const MatrixBase<D2>& w, const QuaternionBase<D3>& q, const MatrixBase<D4>& a_b, const MatrixBase<D5>& w_b, MatrixBase<D6>& a_m, MatrixBase<D7>& w_m)
+//{
+//    MatrixSizeCheck<3,1>::check(a);
+//    MatrixSizeCheck<3,1>::check(w);
+//    MatrixSizeCheck<3,1>::check(a_b);
+//    MatrixSizeCheck<3,1>::check(w_b);
+//    MatrixSizeCheck<3,1>::check(a_m);
+//    MatrixSizeCheck<3,1>::check(w_m);
+//
+//    // Note: data = (a_m , w_m)
+//    a_m = a + a_b - q.conjugate()*gravity();
+//    w_m = w + w_b;
+//}
+//
+///* Create Imu data from body motion
+// * Input:
+// *   motion : [ax, ay, az, wx, wy, wz] the motion in body frame
+// *   q      : the current orientation wrt horizontal
+// *   bias   : the bias of the Imu
+// * Output:
+// *   return : the data vector as created by the Imu (with motion, gravity, and bias)
+// */
+//template<typename D1, typename D2, typename D3>
+//Matrix<typename D1::Scalar, 6, 1> motion2data(const MatrixBase<D1>& motion, const QuaternionBase<D2>& q, const MatrixBase<D3>& bias)
+//{
+//    Matrix<typename D1::Scalar, 6, 1>      data;
+//    Map<Matrix<typename D1::Scalar, 3, 1>> a_m (data.data()    );
+//    Map<Matrix<typename D1::Scalar, 3, 1>> w_m (data.data() + 3);
+//
+//    motion2data(motion.block(0,0,3,1),
+//                motion.block(3,0,3,1),
+//                q,
+//                bias.block(0,0,3,1),
+//                bias.block(3,0,3,1),
+//                a_m,
+//                w_m   );
+//
+//    return  data;
+//}
+
+} // namespace imu2d
+} // namespace wolf
+
+#endif /* Imu_TOOLS_H_ */
diff --git a/include/imu/processor/processor_imu.h b/include/imu/processor/processor_imu.h
index d82a0afe492f938558eb28c53da70a65fb515b3f..502120cc1400bcd2da109903adc72c219e7a6efe 100644
--- a/include/imu/processor/processor_imu.h
+++ b/include/imu/processor/processor_imu.h
@@ -19,7 +19,7 @@ struct ParamsProcessorImu : public ParamsProcessorMotion
     }
     std::string print() const override
     {
-        return "\n" + ParamsProcessorMotion::print();
+        return ParamsProcessorMotion::print();
     }
 };
 
diff --git a/include/imu/processor/processor_imu2d.h b/include/imu/processor/processor_imu2d.h
new file mode 100644
index 0000000000000000000000000000000000000000..bda61341dad3165764aaf78e1a6a5a7efdf8d373
--- /dev/null
+++ b/include/imu/processor/processor_imu2d.h
@@ -0,0 +1,99 @@
+#ifndef PROCESSOR_IMU2D_H
+#define PROCESSOR_IMU2D_H
+
+// Wolf
+#include "imu/capture/capture_imu.h"
+#include "imu/feature/feature_imu.h"
+#include "core/processor/processor_motion.h"
+
+namespace wolf {
+WOLF_STRUCT_PTR_TYPEDEFS(ParamsProcessorImu2d);
+
+struct ParamsProcessorImu2d : public ParamsProcessorMotion
+{
+    ParamsProcessorImu2d() = default;
+    ParamsProcessorImu2d(std::string _unique_name, const ParamsServer& _server):
+        ParamsProcessorMotion(_unique_name, _server)
+    {
+        //
+    }
+    std::string print() const override
+    {
+        return ParamsProcessorMotion::print();
+    }
+};
+
+WOLF_PTR_TYPEDEFS(ProcessorImu2d);
+
+//class
+class ProcessorImu2d : public ProcessorMotion{
+    public:
+        ProcessorImu2d(ParamsProcessorImu2dPtr _params_motion_Imu);
+        ~ProcessorImu2d() override;
+        void configure(SensorBasePtr _sensor) override { };
+
+        WOLF_PROCESSOR_CREATE(ProcessorImu2d, ParamsProcessorImu2d);
+        void preProcess() override;
+
+    protected:
+        void computeCurrentDelta(const Eigen::VectorXd& _data,
+                                         const Eigen::MatrixXd& _data_cov,
+                                         const Eigen::VectorXd& _calib,
+                                         const double _dt,
+                                         Eigen::VectorXd& _delta,
+                                         Eigen::MatrixXd& _delta_cov,
+                                         Eigen::MatrixXd& _jacobian_calib) const override;
+        void deltaPlusDelta(const Eigen::VectorXd& _delta_preint,
+                                    const Eigen::VectorXd& _delta,
+                                    const double _dt,
+                                    Eigen::VectorXd& _delta_preint_plus_delta) const override;
+        void deltaPlusDelta(const Eigen::VectorXd& _delta_preint,
+                                    const Eigen::VectorXd& _delta,
+                                    const double _dt,
+                                    Eigen::VectorXd& _delta_preint_plus_delta,
+                                    Eigen::MatrixXd& _jacobian_delta_preint,
+                                    Eigen::MatrixXd& _jacobian_delta) const override;
+        void statePlusDelta(const VectorComposite& _x,
+                                    const Eigen::VectorXd& _delta,
+                                    const double _Dt,
+                                    VectorComposite& _x_plus_delta) const override;
+        Eigen::VectorXd deltaZero() const override;
+        Eigen::VectorXd correctDelta(const Eigen::VectorXd& delta_preint,
+                                             const Eigen::VectorXd& delta_step) const override;
+        VectorXd getCalibration (const CaptureBasePtr _capture) const override;
+        void setCalibration(const CaptureBasePtr _capture, const VectorXd& _calibration) override;
+        bool voteForKeyFrame() const override;
+        CaptureMotionPtr emplaceCapture(const FrameBasePtr& _frame_own,
+                                                const SensorBasePtr& _sensor,
+                                                const TimeStamp& _ts,
+                                                const VectorXd& _data,
+                                                const MatrixXd& _data_cov,
+                                                const VectorXd& _calib,
+                                                const VectorXd& _calib_preint,
+                                                const CaptureBasePtr& _capture_origin) override;
+        FeatureBasePtr emplaceFeature(CaptureMotionPtr _capture_motion) override;
+        FactorBasePtr emplaceFactor(FeatureBasePtr _feature_motion,
+                                            CaptureBasePtr _capture_origin) override;
+
+    protected:
+        ParamsProcessorImu2dPtr params_motion_Imu_;
+        Eigen::Matrix<double, 5, 5> unmeasured_perturbation_cov_;
+
+};
+
+}
+
+/////////////////////////////////////////////////////////
+// IMPLEMENTATION. Put your implementation includes here
+/////////////////////////////////////////////////////////
+
+namespace wolf{
+
+inline Eigen::VectorXd ProcessorImu2d::deltaZero() const
+{
+    return (Eigen::VectorXd(5) << 0,0,  0,  0,0 ).finished(); // p, q, v
+}
+
+} // namespace wolf
+
+#endif // PROCESSOR_Imu_H
diff --git a/include/imu/sensor/sensor_imu.h b/include/imu/sensor/sensor_imu.h
index e875fde93d4d5ed446e7c433e142b2f8c917cdb7..07b289c0ac0e21451dbe682774d3aeddc79ffa7b 100644
--- a/include/imu/sensor/sensor_imu.h
+++ b/include/imu/sensor/sensor_imu.h
@@ -42,7 +42,7 @@ struct ParamsSensorImu : public ParamsSensorBase
     }
     std::string print() const override
     {
-        return "\n" + ParamsSensorBase::print()                           + "\n"
+        return ParamsSensorBase::print()                           + "\n"
             + "w_noise: "           + std::to_string(w_noise)           + "\n"
             + "a_noise: "           + std::to_string(a_noise)           + "\n"
             + "ab_initial_stdev: "  + std::to_string(ab_initial_stdev)  + "\n"
diff --git a/include/imu/sensor/sensor_imu2d.h b/include/imu/sensor/sensor_imu2d.h
new file mode 100644
index 0000000000000000000000000000000000000000..43fb38693178aea9e06da9c2272071517ac68c5f
--- /dev/null
+++ b/include/imu/sensor/sensor_imu2d.h
@@ -0,0 +1,119 @@
+#ifndef SENSOR_IMU2D_H
+#define SENSOR_IMU2D_H
+
+//wolf includes
+#include "core/sensor/sensor_base.h"
+#include "core/utils/params_server.h"
+#include <iostream>
+
+namespace wolf {
+
+WOLF_STRUCT_PTR_TYPEDEFS(ParamsSensorImu2d);
+
+
+struct ParamsSensorImu2d : public ParamsSensorBase
+{
+    //noise std dev
+    double w_noise = 0.001; //standard deviation of Gyroscope noise (same for all the axis) in rad/sec/ sqrt(s)
+    double a_noise = 0.04; //standard deviation of Acceleration noise (same for all the axis) in m/s2/sqrt(s)
+
+    //Initial biases std dev
+    double ab_initial_stdev = 0.01; //accelerometer micro_g/sec
+    double wb_initial_stdev = 0.01; //gyroscope rad/sec
+
+    // bias rate of change std dev
+    double ab_rate_stdev = 0.00001;
+    double wb_rate_stdev = 0.00001;
+
+    ~ParamsSensorImu2d() override = default;
+    ParamsSensorImu2d()
+    {
+        //DEFINED FOR COMPATIBILITY PURPOSES. TO BE REMOVED IN THE FUTURE.
+    }
+    ParamsSensorImu2d(std::string _unique_name, const ParamsServer& _server):
+        ParamsSensorBase(_unique_name, _server)
+    {
+        w_noise             = _server.getParam<double>(prefix + _unique_name + "/w_noise");
+        a_noise             = _server.getParam<double>(prefix + _unique_name + "/a_noise");
+        ab_initial_stdev    = _server.getParam<double>(prefix + _unique_name + "/ab_initial_stdev");
+        wb_initial_stdev    = _server.getParam<double>(prefix + _unique_name + "/wb_initial_stdev");
+        ab_rate_stdev       = _server.getParam<double>(prefix + _unique_name + "/ab_rate_stdev");
+        wb_rate_stdev       = _server.getParam<double>(prefix + _unique_name + "/wb_rate_stdev");
+    }
+    std::string print() const override
+    {
+        return ParamsSensorBase::print()                           + "\n"
+            + "w_noise: "           + std::to_string(w_noise)           + "\n"
+            + "a_noise: "           + std::to_string(a_noise)           + "\n"
+            + "ab_initial_stdev: "  + std::to_string(ab_initial_stdev)  + "\n"
+            + "wb_initial_stdev: "  + std::to_string(wb_initial_stdev)  + "\n"
+            + "ab_rate_stdev: "     + std::to_string(ab_rate_stdev)     + "\n"
+            + "wb_rate_stdev: "     + std::to_string(wb_rate_stdev)     + "\n";
+    }
+};
+
+WOLF_PTR_TYPEDEFS(SensorImu2d);
+
+class SensorImu2d : public SensorBase
+{
+
+    protected:
+        double a_noise; //Power Spectral Density (same for all the axis) in micro_g/ sqrt(Hz)
+        double w_noise; //Rate Noise Spectral Density (same for all the axis) in deg/sec/ sqrt(Hz)
+
+        //This is a trial to factor how much can the bias change in 1 sec at most
+        double ab_initial_stdev; //accelerometer m/sec^s
+        double wb_initial_stdev; //gyroscope rad/sec
+        double ab_rate_stdev;    //accelerometer m/sec^2 / sqrt(sec)
+        double wb_rate_stdev;    //gyroscope rad/sec / sqrt(sec)
+
+    public:
+
+        SensorImu2d(const Eigen::VectorXd& _extrinsics, const ParamsSensorImu2d& _params);
+        SensorImu2d(const Eigen::VectorXd& _extrinsics, ParamsSensorImu2dPtr _params);
+        WOLF_SENSOR_CREATE(SensorImu2d, ParamsSensorImu2d, 3);
+
+        double getGyroNoise() const;
+        double getAccelNoise() const;
+        double getWbInitialStdev() const;
+        double getAbInitialStdev() const;
+        double getWbRateStdev() const;
+        double getAbRateStdev() const;
+
+        ~SensorImu2d() override;
+
+};
+
+inline double SensorImu2d::getGyroNoise() const
+{
+    return w_noise;
+}
+
+inline double SensorImu2d::getAccelNoise() const
+{
+    return a_noise;
+}
+
+inline double SensorImu2d::getWbInitialStdev() const
+{
+    return wb_initial_stdev;
+}
+
+inline double SensorImu2d::getAbInitialStdev() const
+{
+    return ab_initial_stdev;
+}
+
+inline double SensorImu2d::getWbRateStdev() const
+{
+    return wb_rate_stdev;
+}
+
+inline double SensorImu2d::getAbRateStdev() const
+{
+    return ab_rate_stdev;
+}
+
+} // namespace wolf
+
+#endif // SENSOR_Imu2D_H
diff --git a/src/capture/capture_imu.cpp b/src/capture/capture_imu.cpp
index e0ddfeb680b3f15fb0f8655631a654564f479c7e..75230fafd5663ca7a422497fbd834e4a97e31fe3 100644
--- a/src/capture/capture_imu.cpp
+++ b/src/capture/capture_imu.cpp
@@ -17,7 +17,7 @@ CaptureImu::CaptureImu(const TimeStamp& _init_ts,
                               _capture_origin_ptr,
                               nullptr,
                               nullptr,
-                              std::make_shared<StateBlock>(6, false))
+                              std::make_shared<StateBlock>((_sensor_ptr->getProblem()->getDim() == 2 ? 3 : 6), false))
 {
     //
 }
@@ -26,7 +26,7 @@ CaptureImu::CaptureImu(const TimeStamp& _init_ts,
                        SensorBasePtr _sensor_ptr,
                        const Eigen::Vector6d& _acc_gyro_data,
                        const Eigen::MatrixXd& _data_cov,
-                       const Vector6d& _bias,
+                       const VectorXd& _bias,
                        CaptureBasePtr _capture_origin_ptr) :
                 CaptureMotion("CaptureImu",
                               _init_ts,
@@ -38,7 +38,7 @@ CaptureImu::CaptureImu(const TimeStamp& _init_ts,
                               nullptr,
                               std::make_shared<StateBlock>(_bias, false))
 {
-    //
+    assert((_bias.size() == 3) or (_bias.size() == 6));
 }
 
 CaptureImu::~CaptureImu()
diff --git a/src/feature/feature_imu2d.cpp b/src/feature/feature_imu2d.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..1a5e61a0d0a88629f37d84f96e3605933636ce3e
--- /dev/null
+++ b/src/feature/feature_imu2d.cpp
@@ -0,0 +1,28 @@
+#include "imu/feature/feature_imu2d.h"
+
+namespace wolf {
+
+FeatureImu2d::FeatureImu2d(const Eigen::VectorXd& _delta_preintegrated,
+                       const Eigen::MatrixXd& _delta_preintegrated_covariance,
+                       const Eigen::Vector3d& _bias,
+                       const Eigen::Matrix<double,5,3>& _dD_db_jacobians,
+                       CaptureMotionPtr _cap_imu_ptr) :
+    FeatureBase("FeatureImu2d", _delta_preintegrated, _delta_preintegrated_covariance),
+    bias_preint_(_bias),
+    jacobian_bias_(_dD_db_jacobians)
+{
+}
+
+FeatureImu2d::FeatureImu2d(CaptureMotionPtr _cap_imu_ptr):
+        FeatureBase("FeatureImu2d", _cap_imu_ptr->getDeltaPreint(), _cap_imu_ptr->getDeltaPreintCov()),
+        bias_preint_ (_cap_imu_ptr->getCalibrationPreint()),
+        jacobian_bias_(_cap_imu_ptr->getJacobianCalib())
+{
+}
+
+FeatureImu2d::~FeatureImu2d()
+{
+    //
+}
+
+} // namespace wolf
diff --git a/src/processor/processor_imu2d.cpp b/src/processor/processor_imu2d.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..5c5e911c1edcf6319946b1d3a095e29317820522
--- /dev/null
+++ b/src/processor/processor_imu2d.cpp
@@ -0,0 +1,245 @@
+// imu
+#include "imu/processor/processor_imu2d.h"
+#include "imu/factor/factor_imu2d.h"
+#include "imu/math/imu2d_tools.h"
+
+// wolf
+#include <core/state_block/state_composite.h>
+
+namespace wolf {
+
+  ProcessorImu2d::ProcessorImu2d(ParamsProcessorImu2dPtr _params_motion_imu) :
+    ProcessorMotion("ProcessorImu2d", "POV", 2, 5, 5, 5, 6, 3, _params_motion_imu),
+    params_motion_Imu_(std::make_shared<ParamsProcessorImu2d>(*_params_motion_imu))
+  {
+    // Set constant parts of Jacobians
+    jacobian_delta_preint_.setIdentity(5,5);                                    // dDp'/dDp, dDv'/dDv, all zeros
+    jacobian_delta_.setIdentity(5,5);                                           //
+    jacobian_calib_.setZero(5,3);
+    unmeasured_perturbation_cov_ = pow(params_motion_Imu_->unmeasured_perturbation_std, 2.0) * Eigen::Matrix<double, 5, 5>::Identity();
+  }
+
+  ProcessorImu2d::~ProcessorImu2d()
+  {
+    //
+  }
+
+  void ProcessorImu2d::preProcess()
+  {
+    auto cap_ptr = std::dynamic_pointer_cast<CaptureImu>(incoming_ptr_);
+    assert(cap_ptr != nullptr && ("Capture type mismatch. Processor " + getName() + " can only process captures of type CaptureImu").c_str());
+  }
+
+  bool ProcessorImu2d::voteForKeyFrame() const
+  {
+    // time span
+    if (getBuffer().back().ts_ - getBuffer().front().ts_ > params_motion_Imu_->max_time_span)
+    {
+      WOLF_DEBUG( "PM: vote: time span" );
+      return true;
+    }
+    // buffer length
+    if (getBuffer().size() > params_motion_Imu_->max_buff_length)
+    {
+      WOLF_DEBUG( "PM: vote: buffer length" );
+      return true;
+    }
+    // angle turned
+    double angle = std::abs(delta_integrated_(2));
+    if (angle > params_motion_Imu_->angle_turned)
+    {
+      WOLF_DEBUG( "PM: vote: angle turned" );
+      return true;
+    }
+    //WOLF_DEBUG( "PM: do not vote" );
+    return false;
+  }
+
+
+  CaptureMotionPtr ProcessorImu2d::emplaceCapture(const FrameBasePtr& _frame_own,
+                                                  const SensorBasePtr& _sensor,
+                                                  const TimeStamp& _ts,
+                                                  const VectorXd& _data,
+                                                  const MatrixXd& _data_cov,
+                                                  const VectorXd& _calib,
+                                                  const VectorXd& _calib_preint,
+                                                  const CaptureBasePtr& _capture_origin)
+  {
+    auto cap_motion = std::static_pointer_cast<CaptureMotion>(CaptureBase::emplace<CaptureImu>(_frame_own,
+                                                                                              _ts,
+                                                                                              _sensor,
+                                                                                              _data,
+                                                                                              _data_cov,
+                                                                                              _capture_origin));
+    setCalibration(cap_motion, _calib);
+    cap_motion->setCalibrationPreint(_calib_preint);
+
+    return cap_motion;
+  }
+
+  FeatureBasePtr ProcessorImu2d::emplaceFeature(CaptureMotionPtr _capture_motion)
+  {
+    auto feature = FeatureBase::emplace<FeatureImu2d>(_capture_motion,
+                                                      _capture_motion->getBuffer().back().delta_integr_,
+                                                      _capture_motion->getBuffer().back().delta_integr_cov_ + unmeasured_perturbation_cov_,
+                                                      _capture_motion->getCalibrationPreint(),
+                                                      _capture_motion->getBuffer().back().jacobian_calib_);
+    return feature;
+  }
+
+  VectorXd ProcessorImu2d::getCalibration (const CaptureBasePtr _capture) const
+  {
+      if (_capture)
+          return _capture->getStateBlock('I')->getState();
+      else
+          return getSensor()->getStateBlockDynamic('I')->getState();
+  }
+
+  void ProcessorImu2d::setCalibration (const CaptureBasePtr _capture, const VectorXd& _calibration)
+  {
+    _capture->getSensorIntrinsic()->setState(_calibration);
+  }
+
+  FactorBasePtr ProcessorImu2d::emplaceFactor(FeatureBasePtr _feature_motion, CaptureBasePtr _capture_origin)
+  {
+    CaptureImuPtr cap_imu = std::static_pointer_cast<CaptureImu>(_capture_origin);
+    FeatureImu2dPtr ftr_imu = std::static_pointer_cast<FeatureImu2d>(_feature_motion);
+
+    auto fac_imu = FactorBase::emplace<FactorImu2d>(_feature_motion, ftr_imu, cap_imu, shared_from_this(), params_->apply_loss_function);
+
+    return fac_imu;
+  }
+
+  void ProcessorImu2d::computeCurrentDelta(const Eigen::VectorXd& _data,
+                                          const Eigen::MatrixXd& _data_cov,
+                                          const Eigen::VectorXd& _calib,
+                                          const double _dt,
+                                          Eigen::VectorXd& _delta,
+                                          Eigen::MatrixXd& _delta_cov,
+                                          Eigen::MatrixXd& _jac_delta_calib) const
+  {
+    using namespace Eigen;
+    assert(_data.size() == data_size_ && "Wrong data size!");
+    Vector3d data_2d;
+    data_2d << _data(0), _data(1), _data(5);
+    Matrix3d data_cov_2d;
+    data_cov_2d << _data_cov(0,0), _data_cov(0,1), _data_cov(0,5),
+                  _data_cov(1,0), _data_cov(1,1), _data_cov(1,5),
+                  _data_cov(5,0), _data_cov(5,1), _data_cov(5,5);
+
+
+
+    Matrix<double, 5, 3> jac_delta_data;
+    /*
+     * We have the following computing pipeline:
+     *     Input: data, calib, dt
+     *     Output: delta, delta_cov, jac_calib
+     *
+     * We do:
+     *     body         = data - calib (measurement - bias)
+     *     delta        = body2delta(body, dt) --> jac_body
+     *     jac_data     = jac_body
+     *     jac_calib    = - jac_body
+     *     delta_cov  <-- propagate data_cov using jac_data
+     *
+     * where body2delta(.) produces a delta from body=(a,w) as follows:
+     *     dp = P * a * dt^2
+     *     dth = exp(w * dt) = w * dt
+     *     dv = Q * a * dt
+     * where P and Q are defined in imu2d::exp(), and also a jacobian J^delta_data
+     */
+
+    //create delta
+    imu2d::body2delta(data_2d - _calib, _dt, _delta, jac_delta_data);
+
+    // compute delta_cov
+    _delta_cov = jac_delta_data * data_cov_2d * jac_delta_data.transpose();
+
+    // compute jacobian_calib
+    _jac_delta_calib = - jac_delta_data;
+  }
+
+  void ProcessorImu2d::deltaPlusDelta(const Eigen::VectorXd& _delta_preint,
+                                      const Eigen::VectorXd& _delta,
+                                      const double _dt,
+                                      Eigen::VectorXd& _delta_preint_plus_delta) const
+  {
+    /* MATHS:
+     * Simple composition,
+     * (D o d)p   =   Dp + Dth*dp + Dv*dt
+     * (D o d)th  =   Dth+dth
+     * (D o d)v   =   Dv + Dth*dv
+     * where Dth*dp and Dth*dv are rotations and not scalar products. The version with jacobians is not used here.
+     */
+    _delta_preint_plus_delta = imu2d::compose(_delta_preint, _delta, _dt);
+  }
+
+  void ProcessorImu2d::statePlusDelta(const VectorComposite& _x,
+                                      const Eigen::VectorXd& _delta,
+                                      const double _dt,
+                                      VectorComposite& _x_plus_delta) const
+  {
+    assert(_x.includesStructure("POV") && "Any key missing in _x");
+    assert(_delta.size() == 5 && "Wrong _delta vector size");
+    assert(_dt >= 0 && "Time interval _dt is negative!");
+
+    const auto& delta = VectorComposite(_delta, "POV", {2,1,2});
+    /*
+     * MATHS:
+     *
+     * In the absence of gravity (2D case) it's the same as deltaPlusDelta(), so the same compose() function is used
+     */
+    _x_plus_delta = imu2d::compose(_x, delta, _dt);
+
+  }
+
+  void ProcessorImu2d::deltaPlusDelta(const Eigen::VectorXd& _delta_preint,
+                                      const Eigen::VectorXd& _delta,
+                                      const double _dt,
+                                      Eigen::VectorXd& _delta_preint_plus_delta,
+                                      Eigen::MatrixXd& _jacobian_delta_preint,
+                                      Eigen::MatrixXd& _jacobian_delta) const
+  {
+    /*
+     * Expression of the delta integration step, D' = D (+) d:
+     *
+     *     Dp' = Dp + Dv*dt + Dq*dp
+     *     Dv' = Dv + Dq*dv
+     *     Dq' = Dq * dq
+     *
+     * Jacobians for covariance propagation.
+     *
+     * a. With respect to Delta, gives _jacobian_delta_preint = D'_D as:
+     *
+     *   D'_D = [ I    DR*skew(1)*dp    I*dt   
+     *            0    1                0
+     *            0    DR*skew(1)*dv    I   ] 
+     *
+     * b. With respect to delta, gives _jacobian_delta = D'_d as:
+     *
+     *   D'_d = [ DR   0    0
+     *            0    1    0
+     *            0    0    DR ]
+     *
+     * Note: covariance propagation, i.e.,  P+ = D_D * P * D_D' + D_d * M * D_d', is done in ProcessorMotion.
+     */
+    imu2d::compose(_delta_preint, _delta, _dt, _delta_preint_plus_delta, _jacobian_delta_preint, _jacobian_delta); // jacobians tested in imu2d_tools
+  }
+
+  Eigen::VectorXd ProcessorImu2d::correctDelta (const Eigen::VectorXd& delta_preint,
+                                                const Eigen::VectorXd& delta_step) const
+  {
+    return imu2d::plus(delta_preint, delta_step);
+  }
+
+
+} // namespace wolf
+
+// Register in the FactorySensor
+#include "core/processor/factory_processor.h"
+
+namespace wolf
+{
+  WOLF_REGISTER_PROCESSOR(ProcessorImu2d)
+  WOLF_REGISTER_PROCESSOR_AUTO(ProcessorImu2d)
+}
diff --git a/src/sensor/sensor_imu.cpp b/src/sensor/sensor_imu.cpp
index 488378b4f1f60b1baf670bcb80b22f17180d1f52..8f12c8188ea85bdfff31e1a524a667dddd3cd178 100644
--- a/src/sensor/sensor_imu.cpp
+++ b/src/sensor/sensor_imu.cpp
@@ -24,7 +24,7 @@ SensorImu::SensorImu(const Eigen::VectorXd& _extrinsics, const ParamsSensorImu&
         ab_rate_stdev(_params.ab_rate_stdev),
         wb_rate_stdev(_params.wb_rate_stdev)
 {
-    assert(_extrinsics.size() == 7 && "Wrong extrinsics vector size! Should be 7 for 2d.");
+    assert(_extrinsics.size() == 7 && "Wrong extrinsics vector size! Should be 7 for 3d.");
 }
 
 SensorImu::~SensorImu()
diff --git a/src/sensor/sensor_imu2d.cpp b/src/sensor/sensor_imu2d.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..5b4c94103b4a18d155043100692feb49e02443db
--- /dev/null
+++ b/src/sensor/sensor_imu2d.cpp
@@ -0,0 +1,37 @@
+#include <imu/sensor/sensor_imu2d.h>
+#include <core/state_block/state_block.h>
+#include <core/state_block/state_angle.h>
+
+namespace wolf {
+
+SensorImu2d::SensorImu2d(const Eigen::VectorXd& _extrinsics, ParamsSensorImu2dPtr _params) :
+        SensorImu2d(_extrinsics, *_params)
+{
+    //
+}
+
+SensorImu2d::SensorImu2d(const Eigen::VectorXd& _extrinsics, const ParamsSensorImu2d& _params) :
+        SensorBase("SensorImu2d", std::make_shared<StateBlock>(_extrinsics.head(2), true), std::make_shared<StateAngle>(_extrinsics(2), true), std::make_shared<StateBlock>(3, false, nullptr), (Eigen::Vector3d()<<_params.a_noise,_params.a_noise,_params.w_noise).finished(), false, false, true),
+        a_noise(_params.a_noise),
+        w_noise(_params.w_noise),
+        ab_initial_stdev(_params.ab_initial_stdev),
+        wb_initial_stdev(_params.wb_initial_stdev),
+        ab_rate_stdev(_params.ab_rate_stdev),
+        wb_rate_stdev(_params.wb_rate_stdev)
+{
+    assert(_extrinsics.size() == 3 && "Wrong extrinsics vector size! Should be 3 for 2d.");
+}
+
+SensorImu2d::~SensorImu2d()
+{
+    //
+}
+
+} // namespace wolf
+
+// Register in the FactorySensor
+#include "core/sensor/factory_sensor.h"
+namespace wolf {
+WOLF_REGISTER_SENSOR(SensorImu2d)
+WOLF_REGISTER_SENSOR_AUTO(SensorImu2d);
+} // namespace wolf
diff --git a/src/yaml/processor_imu2d_yaml.cpp b/src/yaml/processor_imu2d_yaml.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..5d8e528cf6d1a12d0f31e2dee03bb2d9d9874ee9
--- /dev/null
+++ b/src/yaml/processor_imu2d_yaml.cpp
@@ -0,0 +1,53 @@
+/**
+ * \file processor_imu2d_yaml.cpp
+ *
+ *  Created on: Nov 24, 2020
+ *      \author: igeer
+ */
+
+// wolf yaml
+#include "imu/processor/processor_imu2d.h"
+#include "core/yaml/yaml_conversion.h"
+
+// wolf
+#include "core/common/factory.h"
+
+// yaml-cpp library
+#include <yaml-cpp/yaml.h>
+
+namespace wolf
+{
+
+namespace
+{
+static ParamsProcessorBasePtr createProcessorImu2dParams(const std::string & _filename_dot_yaml)
+{
+    YAML::Node config = YAML::LoadFile(_filename_dot_yaml);
+    std::cout << _filename_dot_yaml << '\n';
+
+    if (config["type"].as<std::string>() == "ProcessorImu2d")
+    {
+        YAML::Node kf_vote = config["keyframe_vote"];
+
+        ParamsProcessorImu2dPtr params = std::make_shared<ParamsProcessorImu2d>();
+        params->time_tolerance = config["time_tolerance"]           .as<double>();
+        params->unmeasured_perturbation_std = config["unmeasured_perturbation_std"].as<double>();
+
+        params->max_time_span       = kf_vote["max_time_span"]      .as<double>();
+        params->max_buff_length     = kf_vote["max_buff_length"]    .as<SizeEigen>();
+        params->dist_traveled       = kf_vote["dist_traveled"]      .as<double>();
+        params->angle_turned        = kf_vote["angle_turned"]       .as<double>();
+        params->voting_active       = kf_vote["voting_active"]      .as<bool>();
+        return params;
+    }
+
+    std::cout << "Bad configuration file. No processor type found." << std::endl;
+    return nullptr;
+}
+
+// Register in the FactorySensor
+const bool WOLF_UNUSED registered_prc_imu2d = FactoryParamsProcessor::registerCreator("ProcessorImu2d", createProcessorImu2dParams);
+
+} // namespace [unnamed]
+
+} // namespace wolf
diff --git a/src/yaml/sensor_imu2d_yaml.cpp b/src/yaml/sensor_imu2d_yaml.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..286e6fb247c253bed93919475c63e753d12f09e7
--- /dev/null
+++ b/src/yaml/sensor_imu2d_yaml.cpp
@@ -0,0 +1,54 @@
+/**
+ * \file sensor_imu2d_yaml.cpp
+ *
+ *  Created on: Nov 24, 2020
+ *      \author: igeer
+ */
+
+// wolf yaml
+#include "imu/sensor/sensor_imu2d.h"
+#include "core/yaml/yaml_conversion.h"
+
+// wolf
+#include "core/common/factory.h"
+
+// yaml-cpp library
+#include <yaml-cpp/yaml.h>
+
+namespace wolf
+{
+
+namespace
+{
+
+static ParamsSensorBasePtr createParamsSensorImu2d(const std::string & _filename_dot_yaml)
+{
+    YAML::Node config = YAML::LoadFile(_filename_dot_yaml);
+
+    if (config["type"].as<std::string>() == "SensorImu2d")
+    {
+        YAML::Node variances        = config["motion_variances"];
+        YAML::Node kf_vote          = config["keyframe_vote"];
+
+        ParamsSensorImu2dPtr params = std::make_shared<ParamsSensorImu2d>();
+
+        params->a_noise             = variances["a_noise"]          .as<double>();
+        params->w_noise             = variances["w_noise"]          .as<double>();
+        params->ab_initial_stdev    = variances["ab_initial_stdev"] .as<double>();
+        params->wb_initial_stdev    = variances["wb_initial_stdev"] .as<double>();
+        params->ab_rate_stdev       = variances["ab_rate_stdev"]    .as<double>();
+        params->wb_rate_stdev       = variances["wb_rate_stdev"]    .as<double>();
+
+        return params;
+    }
+
+    std::cout << "Bad configuration file. No sensor type found." << std::endl;
+    return nullptr;
+}
+
+// Register in the FactorySensor
+const bool WOLF_UNUSED registered_imu2d_intr = FactoryParamsSensor::registerCreator("SensorImu2d", createParamsSensorImu2d);
+
+} // namespace [unnamed]
+
+} // namespace wolf
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 42bce1a6d1364c4ea6af8943a55efcbc88345aad..d16b4a3857c88316a48fa5cc79f77a6bc4f7b40d 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -16,18 +16,27 @@ target_link_libraries(gtest_example ${PLUGIN_NAME})      #
 wolf_add_gtest(gtest_processor_imu gtest_processor_imu.cpp)
 target_link_libraries(gtest_processor_imu ${PLUGIN_NAME} ${wolf_LIBRARY})
 
+wolf_add_gtest(gtest_processor_imu2d gtest_processor_imu2d.cpp)
+target_link_libraries(gtest_processor_imu2d ${PLUGIN_NAME} ${wolf_LIBRARY})
+
 wolf_add_gtest(gtest_imu gtest_imu.cpp)
 target_link_libraries(gtest_imu ${PLUGIN_NAME} ${wolf_LIBRARY})
 
 wolf_add_gtest(gtest_imu_tools gtest_imu_tools.cpp)
 target_link_libraries(gtest_imu_tools ${PLUGIN_NAME} ${wolf_LIBRARY})
 
+wolf_add_gtest(gtest_imu2d_tools gtest_imu2d_tools.cpp)
+target_link_libraries(gtest_imu2d_tools ${PLUGIN_NAME} ${wolf_LIBRARY})
+
 wolf_add_gtest(gtest_processor_imu_jacobians gtest_processor_imu_jacobians.cpp)
 target_link_libraries(gtest_processor_imu_jacobians ${PLUGIN_NAME} ${wolf_LIBRARY})
 
 wolf_add_gtest(gtest_feature_imu gtest_feature_imu.cpp)
 target_link_libraries(gtest_feature_imu ${PLUGIN_NAME} ${wolf_LIBRARY})
 
+wolf_add_gtest(gtest_factor_imu2d gtest_factor_imu2d.cpp)
+target_link_libraries(gtest_factor_imu2d ${PLUGIN_NAME} ${wolf_LIBRARY})
+
 wolf_add_gtest(gtest_imu_mocap_fusion gtest_imu_mocap_fusion.cpp)
 target_link_libraries(gtest_imu_mocap_fusion ${PLUGIN_NAME} ${wolf_LIBRARY})
 
@@ -43,4 +52,4 @@ wolf_add_gtest(gtest_processor_motion_intrinsics_update gtest_processor_motion_i
 target_link_libraries(gtest_processor_motion_intrinsics_update ${PLUGIN_NAME} ${wolf_LIBRARY})
 
 wolf_add_gtest(gtest_sensor_compass gtest_sensor_compass.cpp)
-target_link_libraries(gtest_sensor_compass ${PLUGIN_NAME} ${wolf_LIBRARY})
\ No newline at end of file
+target_link_libraries(gtest_sensor_compass ${PLUGIN_NAME} ${wolf_LIBRARY})
diff --git a/test/gtest_factor_imu2d.cpp b/test/gtest_factor_imu2d.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..037783f6966b9c96f7016371469c7b522a6ded14
--- /dev/null
+++ b/test/gtest_factor_imu2d.cpp
@@ -0,0 +1,425 @@
+#include <core/ceres_wrapper/solver_ceres.h>
+#include <core/utils/utils_gtest.h>
+
+#include "imu/factor/factor_imu2d.h"
+#include "imu/math/imu2d_tools.h"
+#include "imu/sensor/sensor_imu2d.h"
+
+using namespace Eigen;
+using namespace wolf;
+
+// Input odometry data and covariance
+Matrix6d data_cov = 0.1*Matrix6d::Identity();
+Matrix5d delta_cov = 0.1*Matrix5d::Identity();
+
+// Jacobian of the bias
+MatrixXd jacobian_bias((MatrixXd(5,3) << 1, 0, 0,
+                                         0, 1, 0,
+                                         0, 0, 1,
+                                         1, 0, 0,
+                                         0, 1, 0 ).finished());
+//preintegration bias
+Vector3d b0_preint = Vector3d::Zero();
+
+// Problem and solver
+ProblemPtr problem_ptr = Problem::create("POV", 2);
+SolverCeres solver(problem_ptr);
+
+// Two frames
+FrameBasePtr frm0 = problem_ptr->emplaceFrame(TimeStamp(0), Vector5d::Zero());
+FrameBasePtr frm1 = problem_ptr->emplaceFrame(TimeStamp(1), Vector5d::Zero());
+
+// Imu2d sensor
+SensorBasePtr sensor = std::make_shared<SensorImu2d>( Vector3d::Zero(), ParamsSensorImu2d() ); // default params: see sensor_imu2d.h
+
+//capture from frm1 to frm0
+auto cap0 = CaptureBase::emplace<CaptureImu>(frm0, 0, sensor, Vector6d::Zero(), data_cov, Vector3d::Zero(), nullptr);
+auto cap1 = CaptureBase::emplace<CaptureImu>(frm1, 1, sensor, Vector6d::Zero(), data_cov, Vector3d::Zero(), cap0);
+
+TEST(FactorImu2d, check_tree)
+{
+    ASSERT_TRUE(problem_ptr->check(0));
+}
+
+TEST(FactorImu2d, bias_zero_solve_f1)
+{
+  for(int i = 0; i < 50; i++){
+    // Random delta
+    Vector5d delta = Vector5d::Random() * 10; //delta *= 0;
+    delta(2) = pi2pi(delta(2));
+
+    // Random initial pose
+    Vector5d x0 = Vector5d::Random() * 10; //x0 *= 0;
+    x0(2) = pi2pi(x0(2));
+
+    // x1 groundtruth
+    Vector5d x1;
+    x1 = imu2d::compose(x0, delta, 1);
+
+    // Set states
+    frm0->setState(x0);
+    frm1->setState(x1);
+
+    // feature & factor with delta measurement
+    auto fea1 = FeatureBase::emplace<FeatureImu2d>(cap1, delta, delta_cov, b0_preint, jacobian_bias, cap1);
+    FactorBase::emplace<FactorImu2d>(fea1, fea1, cap0, nullptr, false);
+
+    // Fix frm0 and biases, perturb frm1
+    frm0->fix();
+    cap0->fix();
+    frm1->unfix();
+    cap1->fix();
+    frm1->perturb(0.01);
+
+    // solve 
+    std::string report = solver.solve(SolverManager::ReportVerbosity::BRIEF);
+
+    ASSERT_POSE2d_APPROX(frm1->getStateVector(), x1, 1e-6);
+    //WOLF_INFO(frm1->getStateVector());
+
+    // remove feature (and factor) for the next loop
+    fea1->remove();
+}
+}
+
+TEST(FactorImu2d, bias_zero_solve_f0)
+{
+  for(int i = 0; i < 50; i++){
+    // Random delta
+    Vector5d delta = Vector5d::Random() * 10; //delta *= 0;
+    delta(2) = pi2pi(delta(2));
+
+    // Random initial pose
+    Vector5d x0 = Vector5d::Random() * 10; //x0 *= 0;
+    x0(2) = pi2pi(x0(2));
+
+    // x1 groundtruth
+    Vector5d x1;
+    x1 = imu2d::compose(x0, delta, 1);
+
+    // Set states
+    frm0->setState(x0);
+    frm1->setState(x1);
+
+    // feature & factor with delta measurement
+    auto fea1 = FeatureBase::emplace<FeatureImu2d>(cap1, delta, delta_cov, b0_preint, jacobian_bias, cap1);
+    FactorBase::emplace<FactorImu2d>(fea1, fea1, cap0, nullptr, false);
+
+    // Fix frm0 and biases, perturb frm1
+    frm0->unfix();
+    cap0->fix();
+    frm1->fix();
+    cap1->fix();
+    frm0->perturb(0.01);
+
+    // solve 
+    std::string report = solver.solve(SolverManager::ReportVerbosity::BRIEF);
+
+    ASSERT_POSE2d_APPROX(frm0->getStateVector(), x0, 1e-6);
+    //WOLF_INFO(frm1->getStateVector());
+
+    // remove feature (and factor) for the next loop
+    fea1->remove();
+}
+}
+
+TEST(FactorImu2d, bias_zero_solve_b1)
+{
+  for(int i = 0; i < 50; i++){
+    // Random delta
+    Vector5d delta = Vector5d::Random() * 10; //delta *= 0;
+    delta(2) = pi2pi(delta(2));
+
+    // Random initial pose
+    Vector5d x0 = Vector5d::Random() * 10; //x0 *= 0;
+    x0(2) = pi2pi(x0(2));
+
+    // x1 groundtruth
+    Vector5d x1;
+    x1 = imu2d::compose(x0, delta, 1);
+    
+    //0 Initial bias
+    Vector3d b0 = Vector3d::Zero();
+
+    // Set states
+    frm0->setState(x0);
+    frm1->setState(x1);
+    cap0->getStateBlock('I')->setState(b0);
+    cap1->getStateBlock('I')->setState(b0);
+
+    // feature & factor with delta measurement
+    auto fea1 = FeatureBase::emplace<FeatureImu2d>(cap1, delta, delta_cov, b0_preint, jacobian_bias, cap1);
+    FactorBase::emplace<FactorImu2d>(fea1, fea1, cap0, nullptr, false);
+
+    // Fix frm0, frm1 and cap0, unfix cap1 (bias), perturb cap1
+    frm0->fix();
+    cap0->fix();
+    frm1->fix();
+    cap1->unfix();
+    cap1->perturb(0.01);
+
+    // solve  to estimate bias at cap1
+    std::string report = solver.solve(SolverManager::ReportVerbosity::BRIEF);
+
+    ASSERT_MATRIX_APPROX(cap1->getStateVector(), b0, 1e-6);
+    //WOLF_INFO(cap1->getStateVector());
+
+    // remove feature (and factor) for the next loop
+    fea1->remove();
+}
+}
+
+TEST(FactorImu2d, solve_b0)
+{
+  for(int i = 0; i < 50; i++){
+    // Random delta
+    Vector5d delta_biased = Vector5d::Random() * 10;
+    delta_biased(2) = pi2pi(delta_biased(2));
+
+    // Random initial pose
+    Vector5d x0 = Vector5d::Random() * 10;
+    x0(2) = pi2pi(x0(2));
+
+    //Random Initial bias
+    Vector3d b0 = Vector3d::Random();
+
+    //Corrected delta
+    Vector5d delta_step = jacobian_bias*(b0-b0_preint);
+    Vector5d delta = imu2d::plus(delta_biased, delta_step);
+
+    // x1 groundtruth
+    Vector5d x1;
+    x1 = imu2d::compose(x0, delta, 1);
+
+    // Set states
+    frm0->setState(x0);
+    frm1->setState(x1);
+    cap0->getStateBlock('I')->setState(b0);
+    cap1->getStateBlock('I')->setState(b0);
+
+    // feature & factor with delta measurement
+    auto fea1 = FeatureBase::emplace<FeatureImu2d>(cap1, delta_biased, delta_cov, b0_preint, jacobian_bias);
+    FactorBase::emplace<FactorImu2d>(fea1, fea1, cap0, nullptr, false);
+
+    // Fix frm1, perturb frm0
+    frm0->fix();
+    cap0->unfix();
+    frm1->fix();
+    cap1->fix();
+    cap0->perturb(0.1);
+
+    // solve 
+    std::string report = solver.solve(SolverManager::ReportVerbosity::BRIEF);
+
+    ASSERT_POSE2d_APPROX(cap0->getStateVector(), b0, 1e-6);
+    //WOLF_INFO(cap0->getStateVector());
+
+    // remove feature (and factor) for the next loop
+    fea1->remove();
+}
+}
+
+TEST(FactorImu2d, solve_b1)
+{
+  for(int i = 0; i < 50; i++){
+    // Random delta
+    Vector5d delta = Vector5d::Random() * 10; //delta *= 0;
+    delta(2) = pi2pi(delta(2));
+
+    // Random initial pose
+    Vector5d x0 = Vector5d::Random() * 10; //x0 *= 0;
+    x0(2) = pi2pi(x0(2));
+
+    // x1 groundtruth
+    Vector5d x1;
+    x1 = imu2d::compose(x0, delta, 1);
+    
+    //0 Initial bias
+    Vector3d b0 = Vector3d::Random();
+
+    // Set states
+    frm0->setState(x0);
+    frm1->setState(x1);
+    cap0->getStateBlock('I')->setState(b0);
+    cap1->getStateBlock('I')->setState(b0);
+
+    // feature & factor with delta measurement
+    auto fea1 = FeatureBase::emplace<FeatureImu2d>(cap1, delta, delta_cov, b0_preint, jacobian_bias, cap1);
+    FactorBase::emplace<FactorImu2d>(fea1, fea1, cap0, nullptr, false);
+
+    // Fix frm0 and frm1, unfix bias, perturb cap1
+    frm0->fix();
+    cap0->fix();
+    frm1->fix();
+    cap1->unfix();
+    cap1->perturb(0.01);
+
+    // solve  to estimate bias at cap1
+    std::string report = solver.solve(SolverManager::ReportVerbosity::BRIEF);
+
+    ASSERT_MATRIX_APPROX(cap1->getStateVector(), b0, 1e-6);
+    //WOLF_INFO(cap1->getStateVector());
+
+    // remove feature (and factor) for the next loop
+    fea1->remove();
+}
+}
+
+TEST(FactorImu2d, solve_f0)
+{
+  for(int i = 0; i < 50; i++){
+    // Random delta
+    Vector5d delta_biased = Vector5d::Random() * 10;
+    delta_biased(2) = pi2pi(delta_biased(2));
+
+    // Random initial pose
+    Vector5d x0 = Vector5d::Random() * 10;
+    x0(2) = pi2pi(x0(2));
+
+    //Random Initial bias
+    Vector3d b0 = Vector3d::Random();
+
+    //Corrected delta
+    Vector5d delta_step = jacobian_bias*(b0-b0_preint);
+    Vector5d delta = imu2d::plus(delta_biased, delta_step);
+
+    // x1 groundtruth
+    Vector5d x1;
+    x1 = imu2d::compose(x0, delta, 1);
+
+    // Set states
+    frm0->setState(x0);
+    frm1->setState(x1);
+    cap0->getStateBlock('I')->setState(b0);
+    cap1->getStateBlock('I')->setState(b0);
+
+    // feature & factor with delta measurement
+    auto fea1 = FeatureBase::emplace<FeatureImu2d>(cap1, delta_biased, delta_cov, b0_preint, jacobian_bias);
+    FactorBase::emplace<FactorImu2d>(fea1, fea1, cap0, nullptr, false);
+
+    // Fix frm1, perturb frm0
+    frm0->unfix();
+    cap0->fix();
+    frm1->fix();
+    cap1->fix();
+    frm0->perturb(0.1);
+
+    // solve 
+    std::string report = solver.solve(SolverManager::ReportVerbosity::BRIEF);
+
+    ASSERT_POSE2d_APPROX(frm0->getStateVector(), x0, 1e-6);
+    //WOLF_INFO(frm0->getStateVector());
+
+    // remove feature (and factor) for the next loop
+    fea1->remove();
+}
+}
+
+TEST(FactorImu2d, solve_f1)
+{
+  for(int i = 0; i < 50; i++){
+    // Random delta
+    Vector5d delta_biased = Vector5d::Random() * 10;
+    delta_biased(2) = pi2pi(delta_biased(2));
+
+    // Random initial pose
+    Vector5d x0 = Vector5d::Random() * 10;
+    x0(2) = pi2pi(x0(2));
+
+    //Random Initial bias
+    Vector3d b0 = Vector3d::Random();
+
+    //Corrected delta
+    Vector5d delta_step = jacobian_bias*(b0-b0_preint);
+    Vector5d delta = imu2d::plus(delta_biased, delta_step);
+
+    // x1 groundtruth
+    Vector5d x1;
+    x1 = imu2d::compose(x0, delta, 1);
+
+    // Set states
+    frm0->setState(x0);
+    frm1->setState(x1);
+    cap0->getStateBlock('I')->setState(b0);
+    cap1->getStateBlock('I')->setState(b0);
+
+    // feature & factor with delta measurement
+    auto fea1 = FeatureBase::emplace<FeatureImu2d>(cap1, delta_biased, delta_cov, b0_preint, jacobian_bias);
+    FactorBase::emplace<FactorImu2d>(fea1, fea1, cap0, nullptr, false);
+
+    // Fix frm1, perturb frm0
+    frm0->fix();
+    cap0->fix();
+    frm1->unfix();
+    cap1->fix();
+    frm1->perturb(0.1);
+
+    // solve 
+    std::string report = solver.solve(SolverManager::ReportVerbosity::BRIEF);
+
+    ASSERT_POSE2d_APPROX(frm1->getStateVector(), x1, 1e-6);
+    //WOLF_INFO(frm0->getStateVector());
+
+    // remove feature (and factor) for the next loop
+    fea1->remove();
+}
+}
+
+TEST(FactorImu2d, solve_f1_b1)
+{
+  for(int i = 0; i < 50; i++){
+    // Random delta
+    Vector5d delta_biased = Vector5d::Random() * 10;
+    delta_biased(2) = pi2pi(delta_biased(2));
+
+    // Random initial pose
+    Vector5d x0 = Vector5d::Random() * 10;
+    x0(2) = pi2pi(x0(2));
+
+    //Random Initial bias
+    Vector3d b0 = Vector3d::Random();
+
+    //Corrected delta
+    Vector5d delta_step = jacobian_bias*(b0-b0_preint);
+    Vector5d delta = imu2d::plus(delta_biased, delta_step);
+
+    // x1 groundtruth
+    Vector5d x1;
+    x1 = imu2d::compose(x0, delta, 1);
+
+    // Set states
+    frm0->setState(x0);
+    frm1->setState(x1);
+    cap0->getStateBlock('I')->setState(b0);
+    cap1->getStateBlock('I')->setState(b0);
+
+    // feature & factor with delta measurement
+    auto fea1 = FeatureBase::emplace<FeatureImu2d>(cap1, delta_biased, delta_cov, b0_preint, jacobian_bias);
+    FactorBase::emplace<FactorImu2d>(fea1, fea1, cap0, nullptr, false);
+
+    // Fix frm1, perturb frm0
+    frm0->fix();
+    cap0->fix();
+    frm1->unfix();
+    cap1->unfix();
+    frm1->perturb(0.1);
+    cap1->perturb(0.1);
+
+    // solve 
+    std::string report = solver.solve(SolverManager::ReportVerbosity::BRIEF);
+
+    ASSERT_POSE2d_APPROX(frm1->getStateVector(), x1, 1e-6);
+    ASSERT_MATRIX_APPROX(cap1->getStateVector(), b0, 1e-6);
+    //WOLF_INFO(frm0->getStateVector());
+
+    // remove feature (and factor) for the next loop
+    fea1->remove();
+  }
+}
+
+int main(int argc, char **argv)
+{
+    testing::InitGoogleTest(&argc, argv);
+    //    ::testing::GTEST_FLAG(filter) = "FactorImu2d.no_bias_fixed"; // Test only this one
+    return RUN_ALL_TESTS();
+}
diff --git a/test/gtest_feature_imu.cpp b/test/gtest_feature_imu.cpp
index ef63025f2b0db475bae9ceba850f960755570e08..6d2403b6827319b85236fbf444bc3af8987dbc27 100644
--- a/test/gtest_feature_imu.cpp
+++ b/test/gtest_feature_imu.cpp
@@ -68,7 +68,7 @@ class FeatureImu_test : public testing::Test
                                                  sensor_ptr,
                                                  data_,
                                                  Eigen::Matrix6d::Identity(),
-                                                 Eigen::Vector6d::Zero()) );
+                                                 Eigen::Vector6d::Zero().eval()) );
 
     //process data
         data_ << 2, 0, 9.8, 0, 0, 0;
diff --git a/test/gtest_imu2d_tools.cpp b/test/gtest_imu2d_tools.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..f5ce0cd3d35458ddafeca138fc7fa34db8a8f88d
--- /dev/null
+++ b/test/gtest_imu2d_tools.cpp
@@ -0,0 +1,648 @@
+/*
+ * gtest_imu2d_tools.cpp
+ *
+ *  Created on: Nov 17, 2020
+ *      Author: igeer
+ */
+
+#include "imu/math/imu2d_tools.h"
+#include <core/utils/utils_gtest.h>
+
+using namespace Eigen;
+using namespace wolf;
+using namespace imu2d;
+
+TEST(Imu2d_tools, identity)
+{
+    VectorXd id_true;
+    id_true.setZero(5);
+
+    VectorXd id = identity<double>();
+    ASSERT_MATRIX_APPROX(id, id_true, 1e-10);
+}
+
+//TEST(Imu2d_tools, identity_split)
+//{
+//    VectorXd p(3), qv(4), v(3);
+//    Quaterniond q;
+//
+//    identity(p,q,v);
+//    ASSERT_MATRIX_APPROX(p, Vector3d::Zero(), 1e-10);
+//    ASSERT_QUATERNION_APPROX(q, Quaterniond::Identity(), 1e-10);
+//    ASSERT_MATRIX_APPROX(v, Vector3d::Zero(), 1e-10);
+//
+//    identity(p,qv,v);
+//    ASSERT_MATRIX_APPROX(p , Vector3d::Zero(), 1e-10);
+//    ASSERT_MATRIX_APPROX(qv, (Vector4d()<<0,0,0,1).finished(), 1e-10);
+//    ASSERT_MATRIX_APPROX(v , Vector3d::Zero(), 1e-10);
+//}
+
+TEST(Imu2d_tools, inverse)
+{
+    VectorXd d(5), id(5), iid(5), iiid(5), I(5);
+    double dt = 0.1;
+
+    d << 0, 1,   2,   3, 4;
+
+    id = inverse(d, dt);
+
+    compose(id, d, dt, I);
+    ASSERT_MATRIX_APPROX(I, imu2d::identity(), 1e-10);
+    compose(d, id, -dt, I); // Observe -dt is reversed !!
+    ASSERT_MATRIX_APPROX(I, imu2d::identity(), 1e-10);
+
+    inverse(id, -dt, iid); // Observe -dt is reversed !!
+    ASSERT_MATRIX_APPROX( d,  iid, 1e-10);
+    iiid = inverse(iid, dt);
+    ASSERT_MATRIX_APPROX(id, iiid, 1e-10);
+}
+
+TEST(Imu2d_tools, compose){
+    //Compose 2 vectors
+    VectorXd dx1(5), dx2(5), dx3(5);
+    Matrix<double, 5, 1> d1, d2, d3;
+    double dt = 0.001;
+    dx1 << 1, 2,   0.78539816339,  3, 4;
+    d1 = dx1;
+    dx2 << 5, 6,   0.39269908169,  7, 8;
+    d2 = dx2;
+
+    //base function
+    Rotation2D<double> dR1(dx1(2));
+    Vector2d dp2_rot = dR1*dx2.head(2);
+    Vector2d dv2_rot = dR1*dx2.tail(2);
+    Vector2d cdp = dx1.head(2) + dp2_rot + dx1.tail(2)*dt;
+    Vector2d cdv = dx1.tail(2) + dv2_rot;
+    dx3 <<  cdp,
+           dx1(2) + dx2(2),
+           cdv;
+    VectorXd composedmatrix = compose(dx1, dx2, dt);
+    ASSERT_MATRIX_APPROX(dx3, composedmatrix, 1e-10);
+    
+    //// combinations of templates for sum()
+    compose(dx1, dx2, dt, dx3);
+    compose(d1, d2, dt, d3);
+    ASSERT_MATRIX_APPROX(d3, dx3, 1e-10);
+
+    compose(d1, dx2, dt, dx3);
+    d3 = compose(dx1, d2, dt);
+    ASSERT_MATRIX_APPROX(d3, dx3, 1e-10);
+  
+}
+
+TEST(Imu2d_tools, compose_between)
+{
+    VectorXd dx1(5), dx2(5), dx3(5);
+    Matrix<double, 5, 1> d1, d2, d3;
+    double dt = 0.1;
+
+    dx1 << 0, 1,  pi2pi(2),  3, 4;
+    d1 = dx1;
+    dx2 << 5, 6,  pi2pi(7),  8, 9;
+    d2 = dx2;
+    compose(dx1, dx2, dt, dx3);
+    compose(d1, d2, dt, d3);
+
+    // minus(d1, d3) should recover delta_2
+    VectorXd diffx(5);
+    Matrix<double,5,1> diff;
+
+    between(dx1, dx3, dt, diffx);
+    ASSERT_MATRIX_APPROX(diffx, dx2, 1e-10);
+    between(d1, d3, dt, diff);
+    ASSERT_MATRIX_APPROX(diff, d2, 1e-10);
+
+    // minus(d3, d1, -dt) should recover inverse(d2, dt)
+    diff = between(d3, d1, -dt);
+    ASSERT_MATRIX_APPROX(diff, inverse(d2, dt), 1e-10);
+    diffx = between(dx3, dx1, -dt);
+    ASSERT_MATRIX_APPROX(diffx, inverse(dx2, dt), 1e-10);
+}
+
+//TEST(Imu2d_tools, compose_between_with_state)
+//{
+//    VectorXd x(10), d(10), x2(10), x3(10), d2(10), d3(10);
+//    Vector4d qv;
+//    double dt = 0.1;
+//
+//    qv = (Vector4d() << 3, 4, 5, 6).finished().normalized();
+//    x << 0, 1, 2, qv, 7, 8, 9;
+//    qv = (Vector4d() << 6, 5, 4, 3).finished().normalized();
+//    d << 9, 8, 7, qv, 2, 1, 0;
+//
+//    composeOverState(x, d, dt, x2);
+//    x3 = composeOverState(x, d, dt);
+//    ASSERT_MATRIX_APPROX(x3, x2, 1e-10);
+//
+//    // betweenStates(x, x2) should recover d
+//    betweenStates(x, x2, dt, d2);
+//    d3 = betweenStates(x, x2, dt);
+//    ASSERT_MATRIX_APPROX(d2, d, 1e-10);
+//    ASSERT_MATRIX_APPROX(d3, d, 1e-10);
+//    ASSERT_MATRIX_APPROX(betweenStates(x, x2, dt), d, 1e-10);
+//
+//    // x + (x2 - x) = x2
+//    ASSERT_MATRIX_APPROX(composeOverState(x, betweenStates(x, x2, dt), dt), x2, 1e-10);
+//
+//    // (x + d) - x = d
+//    ASSERT_MATRIX_APPROX(betweenStates(x, composeOverState(x, d, dt), dt), d, 1e-10);
+//}
+//
+//TEST(Imu2d_tools, lift_retract)
+//{
+//    VectorXd d_min(9); d_min << 0, 1, 2, .3, .4, .5, 6, 7, 8; // use angles in the ball theta < pi
+//
+//    // transform to delta
+//    VectorXd delta = exp_Imu(d_min);
+//
+//    // expected delta
+//    Vector3d dp = d_min.head(3);
+//    Quaterniond dq = v2q(d_min.segment(3,3));
+//    Vector3d dv = d_min.tail(3);
+//    VectorXd delta_true(10); delta_true << dp, dq.coeffs(), dv;
+//    ASSERT_MATRIX_APPROX(delta, delta_true, 1e-10);
+//
+//    // transform to a new tangent -- should be the original tangent
+//    VectorXd d_from_delta = log_Imu(delta);
+//    ASSERT_MATRIX_APPROX(d_from_delta, d_min, 1e-10);
+//
+//    // transform to a new delta -- should be the previous delta
+//    VectorXd delta_from_d = exp_Imu(d_from_delta);
+//    ASSERT_MATRIX_APPROX(delta_from_d, delta, 1e-10);
+//}
+//
+TEST(Imu2d_tools, plus)
+{
+    VectorXd d1(5), d2(5), d3(5);
+    VectorXd err(5);
+    d1 << 0, 1,  2,  3, 4;
+    err << 0.01, 0.02, 0.03, 0.04, 0.05;
+
+    WOLF_INFO("doing sums");
+    d3.head(2)  = d1.head(2)  +   err.head(2);
+    d3(2)       = d1(2)       +        err(2);
+    d3.tail(2)  = d1.tail(2)  +   err.tail(2);
+
+    WOLF_INFO("doing plus()");
+    imu2d::plus(d1, err, d2);
+    ASSERT_MATRIX_APPROX(diff(d3, d2), VectorXd::Zero(5), 1e-10);
+}
+
+TEST(Imu2d_tools, diff)
+{
+    VectorXd d1(5), d2(5);
+    d1 << 0, 1,  7,  8, 9;
+    d2 = d1;
+
+    VectorXd err(5);
+    diff(d1, d2, err);
+    ASSERT_MATRIX_APPROX(err, VectorXd::Zero(5), 1e-10);
+    ASSERT_MATRIX_APPROX(diff(d1, d2), VectorXd::Zero(5), 1e-10);
+
+    VectorXd d3(5);
+    d3.setRandom(); 
+    err.head(2) = d3.head(2) - d1.head(2);
+    err(2) = d3(2) - d1(2);
+    err.tail(2) = d3.tail(2) - d1.tail(2);
+
+    ASSERT_MATRIX_APPROX(err, diff(d1, d3), 1e-10);
+
+}
+
+TEST(Imu2d_tools, compose_jacobians)
+{
+    VectorXd d1(5), d2(5), d3(5), d1_pert(5), d2_pert(5), d3_pert(5); // deltas
+    VectorXd t1(5), t2(5); // tangents
+    Matrix<double, 5, 5> J1_a, J2_a, J1_n, J2_n;
+    double dt = 0.1;
+    double dx = 1e-6;
+    d1 << 0, 1,   pi2pi(2),   3, 4;
+    d2 << 5, 6,   pi2pi(7),   8, 9;
+
+    // analytical jacobians
+    compose(d1, d2, dt, d3, J1_a, J2_a);
+
+    // numerical jacobians
+    for (unsigned int i = 0; i<5; i++)
+    {
+        t1      . setZero();
+        t1(i)   = dx;
+
+        // Jac wrt first delta
+        d1_pert = imu2d::plus(d1, t1);                //     (d1 + t1)
+        d3_pert = compose(d1_pert, d2, dt);           //     (d1 + t1) + d2
+        t2      = diff(d3, d3_pert);                  //   { (d2 + t1) + d2 } - { d1 + d2 }
+        J1_n.col(i) = t2/dx;                          // [ { (d2 + t1) + d2 } - { d1 + d2 } ] / dx
+
+        // Jac wrt second delta
+        d2_pert = imu2d::plus(d2, t1);                //          (d2 + t1)
+        d3_pert = compose(d1, d2_pert, dt);           //     d1 + (d2 + t1)
+        t2      = diff(d3, d3_pert);                  //   { d1 + (d2 + t1) } - { d1 + d2 }
+        J2_n.col(i) = t2/dx;                          // [ { d1 + (d2 + t1) } - { d1 + d2 } ] / dx
+    }
+
+    // check that numerical and analytical match
+    ASSERT_MATRIX_APPROX(J1_a, J1_n, 1e-4);
+    ASSERT_MATRIX_APPROX(J2_a, J2_n, 1e-4);
+}
+
+//TEST(Imu2d_tools, diff_jacobians)
+//{
+//    //diff with jacobians is not implemented and doesn't seem necessary
+//    VectorXd d1(5), d2(5), d3(5), d1_pert(5), d2_pert(5), d3_pert(5); // deltas
+//    VectorXd t1(5), t2(5); // tangents
+//    Matrix<double, 5, 5> J1_a, J2_a, J1_n, J2_n;
+//    double dx = 1e-6;
+//    d1 << 0, 1,   pi2pi(2),   3, 4;
+//    d2 << 5, 6,   pi2pi(7),   8, 9;
+//
+//    // analytical jacobians
+//    diff(d1, d2, d3, J1_a, J2_a);
+//
+//    // numerical jacobians
+//    for (unsigned int i = 0; i<9; i++)
+//    {
+//        t1      . setZero();
+//        t1(i)   = dx;
+//
+//        // Jac wrt first delta
+//        d1_pert = plus(d1, t1);                 //          (d1 + t1)
+//        d3_pert = diff(d1_pert, d2);            //     d2 - (d1 + t1)
+//        t2      = d3_pert - d3;                 //   { d2 - (d1 + t1) } - { d2 - d1 }
+//        J1_n.col(i) = t2/dx;                    // [ { d2 - (d1 + t1) } - { d2 - d1 } ] / dx
+//
+//        // Jac wrt second delta
+//        d2_pert = plus(d2, t1);                 //     (d2 + t1)
+//        d3_pert = diff(d1, d2_pert);            //     (d2 + t1) - d1
+//        t2      = d3_pert - d3;                 //   { (d2 + t1) - d1 } - { d2 - d1 }
+//        J2_n.col(i) = t2/dx;                    // [ { (d2 + t1) - d1 } - { d2 - d1 } ] / dx
+//    }
+//
+//    // check that numerical and analytical match
+//    ASSERT_MATRIX_APPROX(J1_a, J1_n, 1e-4);
+//    ASSERT_MATRIX_APPROX(J2_a, J2_n, 1e-4);
+//}
+
+TEST(Imu2d_tools, body2delta_jacobians)
+{
+    VectorXd delta(5), delta_pert(5); // deltas
+    VectorXd body(3), pert(3);
+    VectorXd tang(5); // tangents
+    Matrix<double, 5, 3> J_a, J_n; // analytic and numerical jacs
+    double dt = 0.01;
+    double dx = 1e-6;
+    body <<  -1, 1,   0; // jacobians not exact if w != 0
+
+    // analytical jacobians
+    body2delta(body, dt, delta, J_a);
+
+    // numerical jacobians
+    for (unsigned int i = 0; i<3; i++)
+    {
+        pert      . setZero();
+        pert(i)   = dx;
+
+        // Jac wrt first delta
+        delta_pert = body2delta(body + pert, dt);   //     delta(body + pert)
+        tang       = diff(delta, delta_pert);       //   delta(body + pert) -- delta(body)
+        J_n.col(i) = tang/dx;                       // ( delta(body + pert) -- delta(body) ) / dx
+    }
+
+    // check that numerical and analytical match
+    ASSERT_MATRIX_APPROX(J_a, J_n, 1e-4);
+}
+
+//motion2data is not (yet) implemented
+
+//TEST(motion2data, zero)
+//{
+//    Vector6d motion;
+//    Vector6d bias;
+//    Quaterniond q;
+//
+//    motion  .setZero();
+//    bias    .setZero();
+//    q       .setIdentity();
+//
+//    Vector6d data = imu2d::motion2data(motion, q, bias);
+//
+//    Vector6d data_true; data_true << -gravity(), Vector3d::Zero();
+//
+//    ASSERT_MATRIX_APPROX(data, data_true, 1e-12);
+//}
+//
+//TEST(motion2data, motion)
+//{
+//    Vector6d motion, g_extended;
+//    Vector6d bias;
+//    Quaterniond q;
+//
+//    g_extended << gravity() , Vector3d::Zero();
+//
+//    motion  << 1,2,3, 4,5,6;
+//    bias    .setZero();
+//    q       .setIdentity();
+//
+//    Vector6d data = imu2d::motion2data(motion, q, bias);
+//
+//    Vector6d data_true; data_true = motion - g_extended;
+//
+//    ASSERT_MATRIX_APPROX(data, data_true, 1e-12);
+//}
+//
+//TEST(motion2data, bias)
+//{
+//    Vector6d motion, g_extended;
+//    Vector6d bias;
+//    Quaterniond q;
+//
+//    g_extended << gravity() , Vector3d::Zero();
+//
+//    motion  .setZero();
+//    bias    << 1,2,3, 4,5,6;
+//    q       .setIdentity();
+//
+//    Vector6d data = imu2d::motion2data(motion, q, bias);
+//
+//    Vector6d data_true; data_true = bias - g_extended;
+//
+//    ASSERT_MATRIX_APPROX(data, data_true, 1e-12);
+//}
+//
+//TEST(motion2data, orientation)
+//{
+//    Vector6d motion, g_extended;
+//    Vector6d bias;
+//    Quaterniond q;
+//
+//    g_extended << gravity() , Vector3d::Zero();
+//
+//    motion  .setZero();
+//    bias    .setZero();
+//    q       = v2q(Vector3d(M_PI/2, 0, 0)); // turn 90 deg in X axis
+//
+//    Vector6d data = imu2d::motion2data(motion, q, bias);
+//
+//    Vector6d data_true; data_true << 0,-gravity()(2),0, 0,0,0;
+//
+//    ASSERT_MATRIX_APPROX(data, data_true, 1e-12);
+//}
+//
+//TEST(motion2data, AllRandom)
+//{
+//    Vector6d motion, g_extended;
+//    Vector6d bias;
+//    Quaterniond q;
+//
+//    motion      .setRandom();
+//    bias        .setRandom();
+//    q.coeffs()  .setRandom().normalize();
+//
+//    g_extended << q.conjugate()*gravity() , Vector3d::Zero();
+//
+//    Vector6d data = imu2d::motion2data(motion, q, bias);
+//
+//    Vector6d data_true; data_true = motion + bias - g_extended;
+//
+//    ASSERT_MATRIX_APPROX(data, data_true, 1e-12);
+//}
+//
+///* Integrate acc and angVel motion, obtain Delta_preintegrated
+// * Input:
+// *   N: number of steps
+// *   q0: initial orientaiton
+// *   motion: [ax, ay, az, wx, wy, wz] as the true magnitudes in body brame
+// *   bias_real: the real bias of the Imu
+// *   bias_preint: the bias used for Delta pre-integration
+// * Output:
+// *   return: the preintegrated delta
+// */
+//VectorXd integrateDelta(int N, const Quaterniond& q0, const VectorXd& motion, const VectorXd& bias_real, const VectorXd& bias_preint, double dt)
+//{
+//    VectorXd data(6);
+//    VectorXd body(6);
+//    VectorXd delta(10);
+//    VectorXd Delta(10), Delta_plus(10);
+//    Delta << 0,0,0, 0,0,0,1, 0,0,0;
+//    Quaterniond q(q0);
+//    for (int n = 0; n<N; n++)
+//    {
+//        data        = motion2data(motion, q, bias_real);
+//        q           = q*exp_q(motion.tail(3)*dt);
+//        body        = data - bias_preint;
+//        delta       = body2delta(body, dt);
+//        Delta_plus  = compose(Delta, delta, dt);
+//        Delta       = Delta_plus;
+//    }
+//    return Delta;
+//}
+//
+///* Integrate acc and angVel motion, obtain Delta_preintegrated
+// * Input:
+// *   N: number of steps
+// *   q0: initial orientaiton
+// *   motion: [ax, ay, az, wx, wy, wz] as the true magnitudes in body brame
+// *   bias_real: the real bias of the Imu
+// *   bias_preint: the bias used for Delta pre-integration
+// * Output:
+// *   J_D_b: the Jacobian of the preintegrated delta wrt the bias
+// *   return: the preintegrated delta
+// */
+//VectorXd integrateDelta(int N, const Quaterniond& q0, const VectorXd& motion, const VectorXd& bias_real, const VectorXd& bias_preint, double dt, Matrix<double, 9, 6>& J_D_b)
+//{
+//    VectorXd data(6);
+//    VectorXd body(6);
+//    VectorXd delta(10);
+//    Matrix<double, 9, 6> J_d_d, J_d_b;
+//    Matrix<double, 9, 9> J_D_D, J_D_d;
+//    VectorXd Delta(10), Delta_plus(10);
+//    Quaterniond q;
+//
+//    Delta << 0,0,0, 0,0,0,1, 0,0,0;
+//    J_D_b.setZero();
+//    q = q0;
+//    for (int n = 0; n<N; n++)
+//    {
+//        // Simulate data
+//        data = motion2data(motion, q, bias_real);
+//        q    = q*exp_q(motion.tail(3)*dt);
+//        // Motion::integrateOneStep()
+//        {   // Imu::computeCurrentDelta
+//            body  = data - bias_preint;
+//            body2delta(body, dt, delta, J_d_d);
+//            J_d_b = - J_d_d;
+//        }
+//        {   // Imu::deltaPlusDelta
+//            compose(Delta, delta, dt, Delta_plus, J_D_D, J_D_d);
+//        }
+//        // Motion:: jac calib
+//        J_D_b = J_D_D*J_D_b + J_D_d*J_d_b;
+//        // Motion:: buffer
+//        Delta = Delta_plus;
+//    }
+//    return Delta;
+//}
+//
+//TEST(Imu2d_tools, integral_jacobian_bias)
+//{
+//    VectorXd Delta(10), Delta_pert(10); // deltas
+//    VectorXd bias_real(6), pert(6), bias_pert(6), bias_preint(6);
+//    VectorXd body(6), data(6), motion(6);
+//    VectorXd tang(9); // tangents
+//    Matrix<double, 9, 6> J_a, J_n; // analytic and numerical jacs
+//    double dt = 0.001;
+//    double dx = 1e-4;
+//    Quaterniond q0(3, 4, 5, 6); q0.normalize();
+//    motion << .1, .2, .3,   .3, .2, .1;
+//    bias_real   << .002, .004, .001,   .003, .002, .001;
+//    bias_preint << .004, .005, .006,   .001, .002, .003;
+//
+//    int N = 500; // # steps of integration
+//
+//    // Analytical Jacobians
+//    Delta = integrateDelta(N, q0, motion, bias_real, bias_preint, dt, J_a);
+//
+//    // numerical jacobians
+//    for (unsigned int i = 0; i<6; i++)
+//    {
+//        pert       . setZero();
+//        pert(i)    = dx;
+//
+//        bias_pert  = bias_preint + pert;
+//        Delta_pert = integrateDelta(N, q0, motion, bias_real, bias_pert, dt);
+//        tang       = diff(Delta, Delta_pert);       //   Delta(bias + pert) -- Delta(bias)
+//        J_n.col(i) = tang/dx;                       // ( Delta(bias + pert) -- Delta(bias) ) / dx
+//    }
+//
+//    // check that numerical and analytical match
+//    ASSERT_MATRIX_APPROX(J_a, J_n, 1e-4);
+//}
+//
+//TEST(Imu2d_tools, delta_correction)
+//{
+//    VectorXd Delta(10), Delta_preint(10), Delta_corr; // deltas
+//    VectorXd bias(6), pert(6), bias_preint(6);
+//    VectorXd body(6), motion(6);
+//    VectorXd tang(9); // tangents
+//    Matrix<double, 9, 6> J_b; // analytic and numerical jacs
+//    Vector4d qv;;
+//    double dt = 0.001;
+//    Quaterniond q0(3, 4, 5, 6); q0.normalize();
+//    motion << 1, 2, 3,   3, 2, 1; motion *= .1;
+//
+//    int N = 1000; // # steps of integration
+//
+//    // preintegration with correct bias
+//    bias << .004, .005, .006,   .001, .002, .003;
+//    Delta = integrateDelta(N, q0, motion, bias, bias, dt);
+//
+//    // preintegration with wrong bias
+//    pert << .002, -.001, .003,   -.0003, .0002, -.0001;
+//    bias_preint = bias + pert;
+//    Delta_preint = integrateDelta(N, q0, motion, bias, bias_preint, dt, J_b);
+//
+//    // correct perturbated
+//    Vector9d step = J_b*(bias-bias_preint);
+//    Delta_corr = plus(Delta_preint, step);
+//
+//    // Corrected delta should match real delta
+//    ASSERT_MATRIX_APPROX(Delta, Delta_corr, 1e-5);
+//
+//    // diff between real and corrected should be zero
+//    ASSERT_MATRIX_APPROX(diff(Delta, Delta_corr), Vector9d::Zero(), 1e-5);
+//
+//    // diff between preint and corrected deltas should be the jacobian-computed step
+//    ASSERT_MATRIX_APPROX(diff(Delta_preint, Delta_corr), step, 1e-5);
+//}
+//
+//TEST(Imu2d_tools, full_delta_residual)
+//{
+//    VectorXd x1(10), x2(10);
+//    VectorXd Delta(10), Delta_preint(10), Delta_corr(10);
+//    VectorXd Delta_real(9), Delta_err(9), Delta_diff(10), Delta_exp(10);
+//    VectorXd bias(6), pert(6), bias_preint(6), bias_null(6);
+//    VectorXd body(6), motion(6);
+//    VectorXd tang(9); // tangents
+//    Matrix<double, 9, 6> J_b; // analytic and numerical jacs
+//    double dt = 0.001;
+//    Quaterniond q0; q0.setIdentity();
+//
+//    x1          << 0,0,0, 0,0,0,1, 0,0,0;
+//    motion      <<  .3,    .2,    .1,      .1,     .2,     .3; // acc and gyro
+////    motion      <<  .3,    .2,    .1,      .0,     .0,     .0; // only acc
+////    motion      <<  .0,    .0,    .0,      .1,     .2,     .3; // only gyro
+//    bias        << 0.01, 0.02, 0.003,   0.002, 0.005, 0.01;
+//    bias_null   << 0,     0,     0,       0,      0,      0;
+////    bias_preint << 0.003, 0.002, 0.001,   0.001,  0.002,  0.003;
+//    bias_preint = bias_null;
+//
+//    int N = 1000; // # steps of integration
+//
+//    // preintegration with no bias
+//    Delta_real = integrateDelta(N, q0, motion, bias_null, bias_null, dt);
+//
+//    // final state
+//    x2 = composeOverState(x1, Delta_real, 1000*dt);
+//
+//    // preintegration with the correct bias
+//    Delta = integrateDelta(N, q0, motion, bias, bias, dt);
+//
+//    ASSERT_MATRIX_APPROX(Delta, Delta_real, 1e-4);
+//
+//    // preintegration with wrong bias
+//    Delta_preint = integrateDelta(N, q0, motion, bias, bias_preint, dt, J_b);
+//
+//    // compute correction step
+//    Vector9d step = J_b*(bias-bias_preint);
+//
+//    // correct preintegrated delta
+//    Delta_corr = plus(Delta_preint, step);
+//
+//    // Corrected delta should match real delta
+//    ASSERT_MATRIX_APPROX(Delta_real, Delta_corr, 1e-3);
+//
+//    // diff between real and corrected should be zero
+//    ASSERT_MATRIX_APPROX(diff(Delta_real, Delta_corr), Vector9d::Zero(), 1e-3);
+//
+//    // expected delta
+//    Delta_exp = betweenStates(x1, x2, N*dt);
+//
+//    ASSERT_MATRIX_APPROX(Delta_exp, Delta_corr, 1e-3);
+//
+//    // compute diff between expected and corrected
+////    Matrix<double, 9, 9> J_err_exp, J_err_corr;
+//    diff(Delta_exp, Delta_corr, Delta_err); //, J_err_exp, J_err_corr);
+//
+//    ASSERT_MATRIX_APPROX(Delta_err, Vector9d::Zero(), 1e-3);
+//
+//    // compute error between expected and preintegrated
+//    Delta_err = diff(Delta_preint, Delta_exp);
+//
+//    // diff between preint and corrected deltas should be the jacobian-computed step
+//    ASSERT_MATRIX_APPROX(diff(Delta_preint, Delta_corr), step, 1e-3);
+//    /* This implies:
+//     *   - Since D_corr is expected to be similar to D_exp
+//     *      step ~ diff(Delta_preint, Delta_exp)
+//     *   - the residual can be computed with a regular '-' :
+//     *      residual = diff(D_preint, D_exp) - J_bias * (bias - bias_preint)
+//     */
+//
+////    WOLF_TRACE("Delta real: ", Delta_real.transpose());
+////    WOLF_TRACE("x2: ", x2.transpose());
+////    WOLF_TRACE("Delta: ", Delta.transpose());
+////    WOLF_TRACE("Delta pre: ", Delta_preint.transpose());
+////    WOLF_TRACE("Jac bias: \n", J_b);
+////    WOLF_TRACE("Delta step: ", step.transpose());
+////    WOLF_TRACE("Delta cor: ", Delta_corr.transpose());
+////    WOLF_TRACE("Delta exp: ", Delta_exp.transpose());
+////    WOLF_TRACE("Delta err: ", Delta_err.transpose());
+////    WOLF_TRACE("Delta err exp-pre: ", Delta_err.transpose());
+//}
+
+int main(int argc, char **argv)
+{
+  testing::InitGoogleTest(&argc, argv);
+//  ::testing::GTEST_FLAG(filter) = "Imu2d_tools.delta_correction";
+  return RUN_ALL_TESTS();
+}
+
diff --git a/test/gtest_processor_imu.cpp b/test/gtest_processor_imu.cpp
index 4099cf133f000dff71b7eb890c22a9c25c529605..79db6e39e80ca013f5ea4bc833844984fa69d5c3 100644
--- a/test/gtest_processor_imu.cpp
+++ b/test/gtest_processor_imu.cpp
@@ -66,7 +66,7 @@ class ProcessorImut : public testing::Test
         x0.resize(10);
 
         // Create one capture to store the Imu data arriving from (sensor / callback / file / etc.)
-        cap_imu_ptr = make_shared<CaptureImu>(t, sensor_ptr, data, data_cov, Vector6d::Zero());
+        cap_imu_ptr = make_shared<CaptureImu>(t, sensor_ptr, data, data_cov, Vector6d::Zero().eval());
     }
 
     void TearDown() override
@@ -154,7 +154,7 @@ TEST(ProcessorImu, voteForKeyFrame)
     data_cov(0,0) = 0.5;
 
     // Create the captureImu to store the Imu data arriving from (sensor / callback / file / etc.)
-    std::shared_ptr<wolf::CaptureImu> cap_imu_ptr = make_shared<CaptureImu>(t, sensor_ptr, data, data_cov, Vector6d::Zero());
+    std::shared_ptr<wolf::CaptureImu> cap_imu_ptr = make_shared<CaptureImu>(t, sensor_ptr, data, data_cov, Vector6d::Zero().eval());
 
     // process this capture for joining prior KF (t=0) and set it as origin KF
     cap_imu_ptr->process();
diff --git a/test/gtest_processor_imu2d.cpp b/test/gtest_processor_imu2d.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..4e0084f3002024e2bd04cd9896bcb49e798b8cd7
--- /dev/null
+++ b/test/gtest_processor_imu2d.cpp
@@ -0,0 +1,243 @@
+/**
+ * \file gtest_processor_imu2d.cpp
+ *
+ *  Created on: Nov 24, 2020
+ *      \author: igeer
+ */
+
+#include "imu/internal/config.h"
+#include "imu/capture/capture_imu.h"
+#include "imu/processor/processor_imu2d.h"
+#include "imu/sensor/sensor_imu2d.h"
+
+// #include "core/common/wolf.h"
+
+#include <core/utils/utils_gtest.h>
+#include "core/utils/logging.h"
+
+#include "core/math/rotations.h"
+#include <cmath>
+#include <iostream>
+
+using namespace Eigen;
+using namespace wolf;
+
+class ProcessorImu2dTest : public testing::Test
+{
+
+    public: //These can be accessed in fixtures
+        wolf::ProblemPtr problem;
+        wolf::SensorBasePtr sensor_ptr;
+        wolf::ProcessorMotionPtr processor_motion;
+        wolf::TimeStamp t;
+        wolf::TimeStamp t0;
+        double mti_clock, tmp;
+        double dt;
+        Vector6d data;
+        Matrix6d data_cov;
+        VectorComposite     x0c;                                // initial state composite
+        VectorComposite     s0c;                                // initial sigmas composite
+        std::shared_ptr<wolf::CaptureImu> C;
+
+    //a new of this will be created for each new test
+    void SetUp() override
+    {
+        using namespace Eigen;
+        using std::shared_ptr;
+        using std::make_shared;
+        using std::static_pointer_cast;
+        using namespace wolf::Constants;
+
+        std::string wolf_root = _WOLF_IMU_ROOT_DIR;
+
+        // Wolf problem
+        problem = Problem::create("POV", 2);
+        Vector3d extrinsics = (Vector3d() << 0,0, 0).finished();
+        sensor_ptr = problem->installSensor("SensorImu2d", "Main Imu", extrinsics,  wolf_root + "/demos/sensor_imu2d.yaml");
+        ProcessorBasePtr processor_ptr = problem->installProcessor("ProcessorImu2d", "Imu pre-integrator", "Main Imu", wolf_root + "/demos/processor_imu2d.yaml");
+        processor_motion = std::static_pointer_cast<ProcessorMotion>(processor_ptr);
+
+        // Time and data variables
+        dt = 0.01;
+        t0.set(0);
+        t = t0;
+        data = Vector6d::Zero();
+        data_cov = Matrix6d::Identity();
+
+        // Create one capture to store the Imu data arriving from (sensor / callback / file / etc.)
+        C = make_shared<CaptureImu>(t, sensor_ptr, data, data_cov, Vector3d::Zero());
+    }
+
+};
+
+TEST(ProcessorImu2d_constructors, ALL)
+{
+    //constructor with ProcessorImu2dParamsPtr argument only
+    ParamsProcessorImu2dPtr param_ptr = std::make_shared<ParamsProcessorImu2d>();
+    param_ptr->max_time_span =   2.0;
+    param_ptr->max_buff_length = 20000;
+    param_ptr->dist_traveled =   2.0;
+    param_ptr->angle_turned =    2.0;
+
+    ProcessorImu2dPtr prc1 = std::make_shared<ProcessorImu2d>(param_ptr);
+    ASSERT_EQ(prc1->getMaxTimeSpan(), param_ptr->max_time_span);
+    ASSERT_EQ(prc1->getMaxBuffLength(), param_ptr->max_buff_length);
+    ASSERT_EQ(prc1->getDistTraveled(), param_ptr->dist_traveled);
+    ASSERT_EQ(prc1->getAngleTurned(), param_ptr->angle_turned);
+
+    //Factory constructor with pointers
+    std::string wolf_root = _WOLF_IMU_ROOT_DIR;
+    ProblemPtr problem = Problem::create("POV", 2);
+    Vector3d extrinsics = (Vector3d()<<1,0, 0).finished();
+    std::cout << "creating sensor_ptr" << std::endl;
+    SensorBasePtr sensor_ptr = problem->installSensor("SensorImu2d", "Main Imu", extrinsics, wolf_root + "/demos/sensor_imu2d.yaml");
+    std::cout << "created sensor_ptr" << std::endl;
+    ParamsProcessorImu2dPtr params_default = std::make_shared<ParamsProcessorImu2d>();
+    ProcessorBasePtr processor_ptr = problem->installProcessor("ProcessorImu2d", "Imu pre-integrator", sensor_ptr, params_default);
+    ASSERT_EQ(std::static_pointer_cast<ProcessorImu2d>(processor_ptr)->getMaxTimeSpan(),   params_default->max_time_span);
+    ASSERT_EQ(std::static_pointer_cast<ProcessorImu2d>(processor_ptr)->getMaxBuffLength(), params_default->max_buff_length);
+    ASSERT_EQ(std::static_pointer_cast<ProcessorImu2d>(processor_ptr)->getDistTraveled(),  params_default->dist_traveled);
+    ASSERT_EQ(std::static_pointer_cast<ProcessorImu2d>(processor_ptr)->getAngleTurned(),   params_default->angle_turned);
+
+    //Factory constructor with yaml
+    processor_ptr = problem->installProcessor("ProcessorImu2d", "Sec Imu pre-integrator", "Main Imu", wolf_root + "/demos/processor_imu2d.yaml");
+    ASSERT_EQ(std::static_pointer_cast<ProcessorImu2d>(processor_ptr)->getMaxTimeSpan(),   2.0);
+    ASSERT_EQ(std::static_pointer_cast<ProcessorImu2d>(processor_ptr)->getMaxBuffLength(), 20000);
+    ASSERT_EQ(std::static_pointer_cast<ProcessorImu2d>(processor_ptr)->getDistTraveled(),  2.0);
+    ASSERT_EQ(std::static_pointer_cast<ProcessorImu2d>(processor_ptr)->getAngleTurned(),   0.2);
+}
+
+TEST_F(ProcessorImu2dTest, Prior)
+{
+    // Set the origin
+    x0c['P'] = Vector2d(1,2);
+    x0c['O'] = Vector1d(0);
+    x0c['V'] = Vector2d(4,5);
+    auto KF0 = problem->setPriorFix(x0c, t0, dt/2);
+    processor_motion->setOrigin(KF0);
+    //WOLF_DEBUG("x0 =", x0c);
+    //WOLF_DEBUG("KF0 state =", problem->getTrajectory()->getFrameMap().at(t)->getState("POV"));
+}
+
+TEST_F(ProcessorImu2dTest, MRUA)
+{
+   data << 1, 0, 0,   0, 0, 0; 
+   data_cov *= 1e-3;
+   // Set the origin
+   x0c['P'] = Vector2d(1,2);
+   x0c['O'] = Vector1d(0);
+   x0c['V'] = Vector2d(4,5);
+   auto KF0 = problem->setPriorFix(x0c, t0, dt/2);
+   processor_motion->setOrigin(KF0);
+
+   //WOLF_DEBUG("Current State: ", problem->getState());
+   for(t = t0+dt; t <= t0 + 1.0 + dt/2; t+=dt){
+       C->setTimeStamp(t);
+       C->setData(data);
+       C->setDataCovariance(data_cov);
+       C->process();
+       //WOLF_DEBUG("Current State: ", problem->getState()['P'].transpose());
+       //WOLF_DEBUG((x0c['P'] + x0c['V']*(t-t0) + 0.5*data.head(2)*std::pow(t-t0, 2)).transpose());
+       ASSERT_MATRIX_APPROX(x0c['P'] + x0c['V']*(t-t0) + 0.5*data.head(2)*std::pow(t-t0, 2), problem->getState()['P'], 1e-9);
+   }
+}
+
+TEST_F(ProcessorImu2dTest, parabola)
+{
+   double v0 = 10;
+   double a = 1;
+
+   Vector2d pos;
+   // Set the origin
+   x0c['P'] = Vector2d(0, 0);
+   x0c['O'] = Vector1d(0);
+   x0c['V'] = Vector2d(v0, 0);
+
+   data_cov *= 1e-3;
+   auto KF0 = problem->setPriorFix(x0c, t0, dt/2);
+   processor_motion->setOrigin(KF0);
+
+   for(t = t0+dt; t <= t0 + 0.5 + dt/2; t+=dt){
+       C->setTimeStamp(t);
+       data <<  0, a, 0,    0,  0, 0;
+       C->setData(data);
+       C->setDataCovariance(data_cov);
+       C->process();
+       //WOLF_DEBUG("Current State: ", problem->getState());
+       pos << v0*(t-t0),
+              0.5*a*std::pow(t-t0, 2);
+       //WOLF_DEBUG("Calculated State: ", pos.transpose());
+       EXPECT_MATRIX_APPROX(pos , problem->getState()['P'], 1e-9);
+       EXPECT_MATRIX_APPROX(Vector2d(v0, a*(t-t0)), problem->getState()['V'], 1e-9);
+   }
+}
+
+TEST_F(ProcessorImu2dTest, parabola_deluxe)
+{
+   Vector2d v0(13, 56);
+   Vector2d a(1, 2);
+
+   Vector2d pos;
+   // Set the origin
+   x0c['P'] = Vector2d(0, 0);
+   x0c['O'] = Vector1d(0);
+   x0c['V'] = v0;
+
+   data_cov *= 1e-3;
+   auto KF0 = problem->setPriorFix(x0c, t0, dt/2);
+   processor_motion->setOrigin(KF0);
+
+   for(t = t0+dt; t <= t0 + 0.5 + dt/2; t+=dt){
+       C->setTimeStamp(t);
+       data <<  a(0), a(1), 0,    0,  0, 0;
+       C->setData(data);
+       C->setDataCovariance(data_cov);
+       C->process();
+       //WOLF_DEBUG("Current State: ", problem->getState());
+       pos = v0*(t-t0) + 0.5*a*std::pow(t-t0, 2);
+       //WOLF_DEBUG("Calculated State: ", pos.transpose());
+       EXPECT_MATRIX_APPROX(pos , problem->getState()['P'], 1e-9);
+       EXPECT_MATRIX_APPROX(v0 + a*(t-t0), problem->getState()['V'], 1e-9);
+   }
+}
+
+TEST_F(ProcessorImu2dTest, Circular_move)
+{
+   double pi = 3.14159265358993;
+   double r = 1;
+   double w = 1;
+   double alpha = pi/4.;
+   Vector2d pos;
+   // Set the origin
+   x0c['P'] = Vector2d(r, 0);
+   pos = x0c['P'];
+   x0c['O'] = Vector1d(alpha);
+   x0c['V'] = Vector2d(0, w*r);
+
+   data_cov *= 1e-3;
+   //dt = 0.0001;
+   auto KF0 = problem->setPriorFix(x0c, t0, dt/2);
+   processor_motion->setOrigin(KF0);
+
+   WOLF_DEBUG("Current State: ", problem->getState());
+   for(t = t0+dt; t <= t0 + 0.5 + dt/2; t+=dt){
+       C->setTimeStamp(t);
+       data <<  -std::cos(alpha)*w*w*r, std::sin(alpha)*w*w*r, 0,    0,  0, w;
+       C->setData(data);
+       C->setDataCovariance(data_cov);
+       C->process();
+       WOLF_DEBUG("Current State: ", problem->getState());
+       pos << r*std::cos( w*(t-t0) ),
+              r*std::sin( w*(t-t0) );
+       WOLF_DEBUG("Calculated State: ", pos.transpose());
+       EXPECT_MATRIX_APPROX(pos , problem->getState()['P'], 1e-9);
+   }
+}
+
+int main(int argc, char **argv)
+{
+  testing::InitGoogleTest(&argc, argv);
+  //::testing::GTEST_FLAG(filter) = "ProcessorImu2dt.check_Covariance";
+  return RUN_ALL_TESTS();
+}
+
diff --git a/test/processor_imu2d_UnitTester.cpp b/test/processor_imu2d_UnitTester.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..6611c9b1461993fb9fb09268a756d7f13c93f4ec
--- /dev/null
+++ b/test/processor_imu2d_UnitTester.cpp
@@ -0,0 +1,13 @@
+#include "processor_imu2d_UnitTester.h"
+
+namespace wolf {
+
+ProcessorImu2d_UnitTester::ProcessorImu2d_UnitTester() :
+        ProcessorImu2d(std::make_shared<ParamsProcessorImu2d>()),
+        Dq_out_(nullptr)
+{}
+
+ProcessorImu2d_UnitTester::~ProcessorImu2d_UnitTester(){}
+
+} // namespace wolf
+
diff --git a/test/processor_imu2d_UnitTester.h b/test/processor_imu2d_UnitTester.h
new file mode 100644
index 0000000000000000000000000000000000000000..30cd61fed36b4b2e74609c7cfc2af748f0f51f38
--- /dev/null
+++ b/test/processor_imu2d_UnitTester.h
@@ -0,0 +1,379 @@
+
+#ifndef PROCESSOR_IMU2D_UNITTESTER_H
+#define PROCESSOR_IMU2D_UNITTESTER_H
+
+// Wolf
+#include "imu/processor/processor_imu2d.h"
+#include "core/processor/processor_motion.h"
+
+namespace wolf {
+    struct Imu_jac_bias{ //struct used for checking jacobians by finite difference
+
+        Imu_jac_bias(Eigen::Matrix<Eigen::VectorXd,6,1> _Deltas_noisy_vect,
+                     Eigen::VectorXd _Delta0 ,
+                     Eigen::Matrix3d _dDp_dab,
+                     Eigen::Matrix3d _dDv_dab,
+                     Eigen::Matrix3d _dDp_dwb,
+                     Eigen::Matrix3d _dDv_dwb,
+                     Eigen::Matrix3d _dDq_dwb) :
+                         Deltas_noisy_vect_(_Deltas_noisy_vect),
+                         Delta0_(_Delta0) ,
+                         dDp_dab_(_dDp_dab),
+                         dDv_dab_(_dDv_dab),
+                         dDp_dwb_(_dDp_dwb),
+                         dDv_dwb_(_dDv_dwb),
+                         dDq_dwb_(_dDq_dwb)
+        {
+            //
+        }
+                
+        Imu_jac_bias(){
+
+            for (int i=0; i<6; i++){
+                Deltas_noisy_vect_(i) = Eigen::VectorXd::Zero(1,1);
+            }
+
+            Delta0_ = Eigen::VectorXd::Zero(1,1);
+            dDp_dab_ = Eigen::Matrix3d::Zero();
+            dDv_dab_ = Eigen::Matrix3d::Zero();
+            dDp_dwb_ = Eigen::Matrix3d::Zero();
+            dDv_dwb_ = Eigen::Matrix3d::Zero();
+            dDq_dwb_ = Eigen::Matrix3d::Zero();
+        }
+
+        Imu_jac_bias(Imu_jac_bias const & toCopy){
+
+            Deltas_noisy_vect_ = toCopy.Deltas_noisy_vect_;
+            Delta0_  = toCopy.Delta0_;
+            dDp_dab_ = toCopy.dDp_dab_;
+            dDv_dab_ = toCopy.dDv_dab_;
+            dDp_dwb_ = toCopy.dDp_dwb_;
+            dDv_dwb_ = toCopy.dDv_dwb_;
+            dDq_dwb_ = toCopy.dDq_dwb_;
+        }
+
+        public:
+            /*The following vectors will contain all the matrices and deltas needed to compute the finite differences.
+              place 1 : added da_bx in data         place 2 : added da_by in data       place 3 : added da_bz in data
+              place 4 : added dw_bx in data         place 5 : added dw_by in data       place 6 : added dw_bz in data
+             */
+            Eigen::Matrix<Eigen::VectorXd,6,1> Deltas_noisy_vect_;
+            Eigen::VectorXd Delta0_;
+            Eigen::Matrix3d dDp_dab_;
+            Eigen::Matrix3d dDv_dab_;
+            Eigen::Matrix3d dDp_dwb_;
+            Eigen::Matrix3d dDv_dwb_;
+            Eigen::Matrix3d dDq_dwb_;
+
+        public:
+            void copyfrom(Imu_jac_bias const& right){
+
+                Deltas_noisy_vect_ = right.Deltas_noisy_vect_;
+                Delta0_  = right.Delta0_;
+                dDp_dab_ = right.dDp_dab_;
+                dDv_dab_ = right.dDv_dab_;
+                dDp_dwb_ = right.dDp_dwb_;
+                dDv_dwb_ = right.dDv_dwb_;
+                dDq_dwb_ = right.dDq_dwb_;
+            }
+    };
+
+    struct Imu_jac_deltas{
+
+        Imu_jac_deltas(Eigen::VectorXd _Delta0,
+                       Eigen::VectorXd _delta0,
+                       Eigen::Matrix<Eigen::VectorXd,9,1> _Delta_noisy_vect,
+                       Eigen::Matrix<Eigen::VectorXd,9,1> _delta_noisy_vect,
+                       Eigen::MatrixXd _jacobian_delta_preint,
+                       Eigen::MatrixXd _jacobian_delta ) :
+                           Delta0_(_Delta0),
+                           delta0_(_delta0),
+                           Delta_noisy_vect_(_Delta_noisy_vect),
+                           delta_noisy_vect_(_delta_noisy_vect),
+                           jacobian_delta_preint_(_jacobian_delta_preint),
+                           jacobian_delta_(_jacobian_delta)
+        {
+            //
+        }
+
+        Imu_jac_deltas(){
+            for (int i=0; i<9; i++){
+                Delta_noisy_vect_(i) = Eigen::VectorXd::Zero(1,1);
+                delta_noisy_vect_(i) = Eigen::VectorXd::Zero(1,1);
+            }
+
+            Delta0_ = Eigen::VectorXd::Zero(1,1);
+            delta0_ = Eigen::VectorXd::Zero(1,1);
+            jacobian_delta_preint_ = Eigen::MatrixXd::Zero(9,9);
+            jacobian_delta_ = Eigen::MatrixXd::Zero(9,9);
+        }
+
+        Imu_jac_deltas(Imu_jac_deltas const & toCopy){
+
+            Delta_noisy_vect_ = toCopy.Delta_noisy_vect_;
+            delta_noisy_vect_ = toCopy.delta_noisy_vect_;
+
+            Delta0_ = toCopy.Delta0_;
+            delta0_ = toCopy.delta0_;
+            jacobian_delta_preint_ = toCopy.jacobian_delta_preint_;
+            jacobian_delta_ = toCopy.jacobian_delta_;
+        }
+        
+        public:
+            /*The following vectors will contain all the matrices and deltas needed to compute the finite differences.
+              Elements at place 0 are those not affected by the bias noise that we add (Delta_noise, delta_noise -> dPx, dpx, dVx, dvx,..., dOz,doz).
+                            Delta_noisy_vect_                                                                       delta_noisy_vect_
+                            0: + 0,                                                                                 0: + 0
+                            1: +dPx, 2: +dPy, 3: +dPz                                                               1: + dpx, 2: +dpy, 3: +dpz
+                            4: +dOx, 5: +dOy, 6: +dOz                                                               4: + dox, 5: +doy, 6: +doz
+                            7: +dVx, 8: +dVy, 9: +dVz                                                               7: + dvx, 9: +dvy, +: +dvz
+             */
+            Eigen::VectorXd Delta0_; //this will contain the Delta not affected by noise
+            Eigen::VectorXd delta0_; //this will contain the delta not affected by noise
+            Eigen::Matrix<Eigen::VectorXd,9,1> Delta_noisy_vect_; //this will contain the Deltas affected by noises
+            Eigen::Matrix<Eigen::VectorXd,9,1> delta_noisy_vect_; //this will contain the deltas affected by noises
+            Eigen::MatrixXd jacobian_delta_preint_;
+            Eigen::MatrixXd jacobian_delta_;
+
+        public:
+            void copyfrom(Imu_jac_deltas const& right){
+
+                Delta_noisy_vect_       = right.Delta_noisy_vect_;
+                delta_noisy_vect_       = right.delta_noisy_vect_;
+                Delta0_                 = right.Delta0_;
+                delta0_                 = right.delta0_;
+                jacobian_delta_preint_  = right.jacobian_delta_preint_;
+                jacobian_delta_         = right.jacobian_delta_;
+            }
+    };
+
+    class ProcessorImu2d_UnitTester : public ProcessorImu2d{
+
+        public:
+
+        ProcessorImu2d_UnitTester();
+        ~ProcessorImu2d_UnitTester() override;
+
+        //Functions to test jacobians with finite difference method
+
+        /* params :
+            _data : input data vector (size 6 : ax,ay,az,wx,wy,wz)
+            _dt : time interval between 2 Imu measurements
+            da_b : bias noise to add - scalar because adding the same noise to each component of bias (abx, aby, abz, wbx, wby, wbz) one by one. 
+         */
+        Imu_jac_bias finite_diff_ab(const double _dt,
+                                    Eigen::Vector6d& _data,
+                                    const double& da_b,
+                                    const Eigen::Matrix<double,10,1>& _delta_preint0);
+
+        /* params :
+            _data : input data vector (size 6 : ax,ay,az,wx,wy,wz)
+            _dt : time interval between 2 Imu measurements
+            _Delta_noise : noise to add to Delta_preint (D1 in D = D1 + d), vector 9 because rotation expressed as a vector (R2v(q.matrix()))
+            _delta_noise : noise to add to instantaneous delta (d in D = D1 + d), vector 9 because rotation expressed as a vector (R2v(q.matrix()))
+         */
+        Imu_jac_deltas finite_diff_noise(const double& _dt,
+                                         Eigen::Vector6d& _data,
+                                         const Eigen::Matrix<double,9,1>& _Delta_noise,
+                                         const Eigen::Matrix<double,9,1>& _delta_noise,
+                                         const Eigen::Matrix<double,10,1>& _Delta0);
+
+        public:
+        static ProcessorBasePtr create(const std::string& _unique_name,
+                                       const ParamsProcessorBasePtr _params,
+                                       const SensorBasePtr = nullptr);
+
+        public:
+        // Maps quat, to be used as temporary
+        Eigen::Map<Eigen::Quaterniond> Dq_out_;
+
+    };
+
+}
+
+/////////////////////////////////////////////////////////
+// IMPLEMENTATION. Put your implementation includes here
+/////////////////////////////////////////////////////////
+
+// Wolf
+#include "core/state_block/state_block.h"
+#include "core/math/rotations.h"
+
+namespace wolf{
+
+    //Functions to test jacobians with finite difference method
+inline Imu_jac_bias ProcessorImu2d_UnitTester::finite_diff_ab(const double _dt,
+                                                            Eigen::Vector6d& _data,
+                                                            const double& da_b,
+                                                            const Eigen::Matrix<double,10,1>& _delta_preint0)
+{
+    //TODO : need to use a reset function here to make sure jacobians have not been used before --> reset everything
+    ///Define all the needed variables
+    Eigen::VectorXd Delta0;
+    Eigen::Matrix<Eigen::VectorXd,6,1> Deltas_noisy_vect;
+    Eigen::Vector6d data0;
+    data0 = _data;
+
+    Eigen::MatrixXd data_cov;
+    Eigen::MatrixXd jacobian_delta_preint;
+    Eigen::MatrixXd jacobian_delta;
+    Eigen::VectorXd delta_preint_plus_delta0;
+    data_cov.resize(6,6);
+    jacobian_delta_preint.resize(9,9);
+    jacobian_delta.resize(9,9);
+    delta_preint_plus_delta0.resize(10);
+
+    //set all variables to 0
+    data_cov = Eigen::MatrixXd::Zero(6,6);
+    jacobian_delta_preint = Eigen::MatrixXd::Zero(9,9);
+    jacobian_delta = Eigen::MatrixXd::Zero(9,9);
+    delta_preint_plus_delta0 << 0,0,0, 0,0,0,1 ,0,0,0; //PQV
+
+    Vector6d bias = Vector6d::Zero();
+
+    /*The following vectors will contain all the matrices and deltas needed to compute the finite differences.
+        place 1 : added da_bx in data         place 2 : added da_by in data       place 3 : added da_bz in data
+        place 4 : added dw_bx in data         place 5 : added dw_by in data       place 6 : added dw_bz in data
+     */
+
+    Eigen::Matrix3d dDp_dab, dDv_dab, dDp_dwb, dDv_dwb, dDq_dwb;
+
+    //Deltas without use of da_b
+    computeCurrentDelta(_data, data_cov, bias, _dt,delta_,delta_cov_,jacobian_delta_calib_);
+    deltaPlusDelta(_delta_preint0, delta_, _dt, delta_preint_plus_delta0, jacobian_delta_preint, jacobian_delta);
+    MatrixXd jacobian_bias = jacobian_delta * jacobian_delta_calib_;
+    Delta0 = delta_preint_plus_delta0; //this is the first preintegrated delta, not affected by any added bias noise
+    dDp_dab = jacobian_bias.block(0,0,3,3);
+    dDp_dwb = jacobian_bias.block(0,3,3,3);
+    dDq_dwb = jacobian_bias.block(3,3,3,3);
+    dDv_dab = jacobian_bias.block(6,0,3,3);
+    dDv_dwb = jacobian_bias.block(6,3,3,3);
+    
+
+    // propagate bias noise
+    for(int i=0; i<6; i++){
+        //need to reset stuff here
+        delta_preint_plus_delta0 << 0,0,0, 0,0,0,1 ,0,0,0;  //PQV
+        data_cov = Eigen::MatrixXd::Zero(6,6);
+
+        // add da_b
+        _data = data0;
+        _data(i) = _data(i) - da_b; //- because a = a_m − a_b + a_n, in out case, a = a_m − a_b - da_b + a_n
+        //data2delta
+        computeCurrentDelta(_data, data_cov, bias, _dt, delta_, delta_cov_, jacobian_delta_calib_);
+        deltaPlusDelta(_delta_preint0, delta_, _dt, delta_preint_plus_delta0, jacobian_delta_preint, jacobian_delta);
+        Deltas_noisy_vect(i) = delta_preint_plus_delta0; //preintegrated deltas affected by added bias noise
+    }
+
+    Imu_jac_bias bias_jacobians(Deltas_noisy_vect, Delta0, dDp_dab, dDv_dab, dDp_dwb, dDv_dwb, dDq_dwb);
+    return bias_jacobians;
+}
+
+inline Imu_jac_deltas ProcessorImu2d_UnitTester::finite_diff_noise(const double& _dt, Eigen::Vector6d& _data, const Eigen::Matrix<double,9,1>& _Delta_noise, const Eigen::Matrix<double,9,1>& _delta_noise, const Eigen::Matrix<double,10,1>& _Delta0)
+{
+    //we do not propagate any noise from data vector
+    Eigen::VectorXd Delta_; //will contain the preintegrated Delta affected by added noise
+    Eigen::VectorXd delta0; //will contain the delta not affected by added noise
+    // delta_ that /will contain the delta affected by added noise is declared in processor_motion.h
+    Eigen::VectorXd delta_preint_plus_delta;
+    delta0.resize(10);
+    delta_preint_plus_delta.resize(10);
+    delta_preint_plus_delta << 0,0,0 ,0,0,0,1 ,0,0,0;
+
+    Eigen::MatrixXd jacobian_delta_preint;  //will be used as input for deltaPlusDelta
+    Eigen::MatrixXd jacobian_delta;         //will be used as input for deltaPlusDelta
+    jacobian_delta_preint.resize(9,9);
+    jacobian_delta.resize(9,9);
+    jacobian_delta_preint.setIdentity(9,9);
+    jacobian_delta.setIdentity(9,9);
+    Eigen::MatrixXd jacobian_delta_preint0; //will contain the jacobian we want to check
+    Eigen::MatrixXd jacobian_delta0;        //will contain the jacobian we want to check
+    jacobian_delta_preint0.resize(9,9);
+    jacobian_delta0.resize(9,9);
+    jacobian_delta_preint0.setIdentity(9,9);
+    jacobian_delta0.setIdentity(9,9);
+
+    Eigen::MatrixXd data_cov;   //will be used filled with Zeros as input for data2delta
+    data_cov.resize(6,6);
+    data_cov = Eigen::MatrixXd::Zero(6,6);
+
+    Eigen::Matrix<Eigen::VectorXd,9,1> Delta_noisy_vect; //this will contain the Deltas affected by noises
+    Eigen::Matrix<Eigen::VectorXd,9,1> delta_noisy_vect; //this will contain the deltas affected by noises
+
+    Vector6d bias = Vector6d::Zero();
+
+    computeCurrentDelta(_data, data_cov, bias,_dt,delta_,delta_cov_,jacobian_delta_calib_); //Affects dp_out, dv_out and dq_out
+    delta0 = delta_;        //save the delta that is not affected by noise
+    deltaPlusDelta(_Delta0, delta0, _dt, delta_preint_plus_delta, jacobian_delta_preint, jacobian_delta); 
+    jacobian_delta_preint0 = jacobian_delta_preint;
+    jacobian_delta0 = jacobian_delta;
+
+    //We compute all the jacobians wrt deltas and noisy deltas
+    for(int i=0; i<3; i++) //for 3 first and 3 last components we just add to add noise as vector component since it is in the R^3 space
+    {   
+        //PQV formulation
+            //Add perturbation in position
+        delta_ = delta0;
+        delta_(i) = delta_(i) + _delta_noise(i); //noise has been added
+        delta_noisy_vect(i) = delta_;
+
+            //Add perturbation in velocity
+            /*
+            delta_ is size 10 (P Q V),  _delta_noise is size 9 (P O V)
+            */
+        delta_ = delta0;
+        delta_(i+7) = delta_(i+7) + _delta_noise(i+6); //noise has been added
+        delta_noisy_vect(i+6) = delta_;
+    }
+
+    for(int i=0; i<3; i++) //for noise dtheta, it is in SO3, need to work on quaternions
+    {   
+        //PQV formulation
+        //fist we need to reset some stuff
+        Eigen::Vector3d dtheta = Eigen::Vector3d::Zero();
+
+        delta_ = delta0;
+        new (&Dq_out_) Map<Quaterniond>(delta_.data() + 3); //not sure that we need this
+        dtheta(i) +=  _delta_noise(i+3); //introduce perturbation
+        Dq_out_ = Dq_out_ * v2q(dtheta);
+        delta_noisy_vect(i+3) = delta_;
+    }
+
+    //We compute all the jacobians wrt Deltas and noisy Deltas
+    for(int i=0; i<3; i++) //for 3 first and 3 last components we just add to add noise as vector component since it is in the R^3 space
+    {
+        //PQV formulation
+            //Add perturbation in position
+        Delta_ = _Delta0;
+        Delta_(i) = Delta_(i) + _Delta_noise(i); //noise has been added
+        Delta_noisy_vect(i) = Delta_;
+
+            //Add perturbation in velocity
+            /*
+            Delta_ is size 10 (P Q V),  _Delta_noise is size 9 (P O V)
+            */
+        Delta_ = _Delta0;
+        Delta_(i+7) = Delta_(i+7) + _Delta_noise(i+6); //noise has been added
+        Delta_noisy_vect(i+6) = Delta_;
+    }
+
+    for(int i=0; i<3; i++) //for noise dtheta, it is in SO3, need to work on quaternions
+    {
+        //fist we need to reset some stuff
+        Eigen::Vector3d dtheta = Eigen::Vector3d::Zero();
+
+        Delta_ = _Delta0;
+        new (&Dq_out_) Map<Quaterniond>(Delta_.data() + 3);
+        dtheta(i) += _Delta_noise(i+3); //introduce perturbation
+        Dq_out_ = Dq_out_ * v2q(dtheta);
+        Delta_noisy_vect(i+3) = Delta_;
+    }
+    
+    Imu_jac_deltas jac_deltas(_Delta0, delta0, Delta_noisy_vect, delta_noisy_vect, jacobian_delta_preint0, jacobian_delta0);
+    return jac_deltas;
+
+}
+
+} // namespace wolf
+
+#endif // PROCESSOR_Imu_UNITTESTER_H