Noisy velocity command output

[thibpn]

Description

I'm trying to command in velocity a robot by publishing delta_twist commands. The output that I have in velocity_command is extremely noisy.
Here is an example on the first two axes :

To understand where this noise comes from, I installed the source build (humble branch). By modifying it, I identified the Butterworth filter as the source of the noise. When I delete it, I get clean output.

From what I understand, the filter is applied on the joint_states_position + delta_theta. Then, to compute the velocity command :
velocity_command = (filtered(joint_states_position + delta_theta) - joint_states_position) / publish_period

So if my joint_state_position is noisy, my velocity_command will be noisy, which would not have been the case if we used delta_theta to compute velocity commands.

I wish to stay with the binary build. Is there a way to not use any smoothing plugin in Moveit Servo ?

ROS Distro

Humble

OS and version

Ubuntu 22.04

Source or binary build?

Binary

If binary, which release version?

2.5.8-1jammy.20250210.235402

If source, which branch?

No response

Which RMW are you using?

CycloneDDS

Steps to Reproduce

I send delta_twist commands. It need to be slow movement so that delta_theta ~ noise on joint_state.
Then plot velocity_command.

Expected behavior

velocity_command output should not be noisy.

Actual behavior

velocity_command output is noisy.

Backtrace or Console output

No response

[AndyZe]

It's completely optional to have a smoothing plugin as you can see here:

moveit2/moveit_ros/moveit_servo/src/servo.cpp

Line 166 in 7284d36

if (smoother_)

Or, you can try one of the other smoothing options described here:

https://moveit.picknik.ai/main/doc/examples/realtime_servo/realtime_servo_tutorial.html#signal-smoothing

[lparadasanmartin]

Hi @AndyZe , i'm very much interested into knowing how to deactivate the smoother filter !

I tried commenting the line # smoothing_filter_plugin_name: "online_signal_smoothing::ButterworthFilterPlugin" on my servo.yaml file but the filter seems to still apply.

How can I deactivate the smoother for sure ? Thanks a lot for your answer & help.

[sea-bass]

I think since you're using the Humble version, disabling smoothing (or any of the other plugin alternatives) is not available:

moveit2/moveit_ros/moveit_servo/src/servo_calcs.cpp

Line 160 in 954a027

// Load the smoothing plugin

If you upgrade to the Jazzy or Rolling (main) version, there is a parameter to simply disable smoothing. For example:

moveit2/moveit_ros/moveit_servo/config/panda_simulated_config.yaml

Line 30 in 7284d36

use_smoothing: true

You could also consider submitting a PR to Humble to support disabling smoothing, if you'd like to stay on that version. I imagine there's also an option to modify the low-pass filter coefficient in a way that smoothing is effectively a "no operation", without any code changes.