[MoveIt] Executed motions are always slightly off from waypoints

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Hi all,

I've been using MoveIt motion planning (OMPL) to simulate pick&place in the Gazebo environment. And I've noticed that the end-effector of the robot in the simulation is always off (~3cm) from given waypoints it needs to follow.

At the first time, I tried to set a specific tolerance value using MoveGroupCommander.get_goal_position_tolerance, however it did not make much difference. Then, I tried to reduce eef_step when using compute_cartesian_path. It still did not work as expected.

Right now, I'm suspecting that there is something wrong with my controller parameters that hinder the robot to reach to deisred waypoints. Are there any other factors that potentially cause this kind of behavior?