Update README.md

README.md

@@ -6,13 +6,13 @@ The following image is a skecth of the input and output of the node.
 
 <img src="doc/images/landmarks_slam_solver_sketch.png" alt="Image: General overview">
 
-The following image is a basic representation of the slam problem.
+The following image is a basic representation of the slam problem. Is a sequence of robot poses with their landmarks detections connected by the odometry.
 
 <img src="doc/images/slam_problem_sketch.png" alt="Image: Slam problem overview">
 
-When searching for new landmarks, there is a landmarks time persistance filter that checks that a landmark is seen enought times on the same location before adding it as a mapped landmarks.
+When searching for new landmarks, there is a landmark time persistance filter that checks that a landmark is seen enough times on the same location before adding it as a mapped landmarks.
 
-To match a detection with a landmark the [Mahalanobis distance](https://en.wikipedia.org/wiki/Mahalanobis_distance) is used.
+To match a detection with a landmark the [Mahalanobis distance](https://en.wikipedia.org/wiki/Mahalanobis_distance) is used. Basically, a match between a detection and a landmark is done when the detection is inside an ellipse centered on the landmark. The ellipse is defined by the sensor noise and the mahalanobis distance parameter.
 
 On [parameters_adjust.md](./doc/parameters_adjust.md) there is an small explanation on how to adjust the node parameters.