Jerky motion using MoveIt Servo

[AleTarsi]

I am experiencing a problem related to the acceleration profile generated by MoveIt Servo trajectory planner on my UR5e. I’m trying this example of pose tracking. For a bin-picking scenario.

The documentation specifies that MoveIt Servo can enforce only joint position and velocity limits. However, I am experiencing a rough acceleration profile at the start of the motion as shown in the following picture:

At the starting point, the robot joints make an annoying noise, which I want to avoid. During the deceleration phase this noise is not present and the deceleration profile seems much smoother.

I have seen that the time parametrization in MoveIt2 uses the TOTG algorithm to define the velocity and acceleration profiles, which enforce up to the joint acceleration limit. However, it seems that the acceleration limit is not read in MoveIt Servo. I assume that TOTG is used any time you plan using OMPL and Pilz planner, but I haven’t found this information written somewhere. And I would like to understand if changing to Pilz for instance may be a solution to my problem as it enforce at least the acceleration limit.

I have seen there is the possibility to perform an additional post-processing step and run [Ruckig](https://moveit.picknik.ai/humble/doc/examples/time_parameterization/time_parameterization_tutorial.html#time-parameterization-algorithms) algorithm to enforce also the jerk. From the documentation I have seen that this additional plugin is specified in the ompl_planning.yaml, therefore I believe it can be used only when planning with OMPL. Is this true?

As my goal is to remove this unwanted sound when I move my robot, do you think that implementing a vanilla Pilz planner enforcing the acceleration limits is enough? Do you have examples I can take to do so? I am using ros2 Humble.

Is there the possibility of implementing a minimum jerk time parametrization?

Thanks.

[AndyZe]

Your best bet is probably to change this line:

moveit2/moveit_ros/moveit_servo/config/panda_simulated_config_pose_tracking.yaml

Line 31 in f9b5a11

smoothing_filter_plugin_name: "online_signal_smoothing::ButterworthFilterPlugin"

To:

online_signal_smoothing::RuckigFilterPlugin

Which is not in Humble, only later distros. Sorry. I guess you could make a PR to port that change back to Humble.

[AndyZe]

See https://github.com/moveit/moveit2/blob/main/moveit_core/online_signal_smoothing/src/ruckig_filter.cpp