added necessary assert

src/processor/processor_imu2d.cpp

@@ -179,6 +179,7 @@ namespace wolf {
                                       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!");