How robot_pose_ekf update the filter? [closed]

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Hello

Im using a robot_pose_ekf package fusing the wheel odometry from my encoders and the IMU. So we made a couple of runs with our platform that have wheel and we extracted the linear and angular velocity profiles.

I compared the profiles from the robot_pose_kf package with the other ones when for example we were using the Hector Mapping or AMCL localizer. But all of them are more less the same.

So Im confuse about the results because logicaly they shoould be different by robot_pose_ekf and Hector Mapping for example , because robot_pose_ekf was using the odometry massage from the encoders and they should contains velocity ..

So my question is how the robot_pose_ekf update the filter?Is it using the velocity massage from the encoders to update the filter??? Why my velocity profiles are the same by Hector Mapping , AMCL and robot_pose_ekf??Any help??