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ros-controls / gz_ros2_control

Connect the latest version of Gazebo with ros2_control.
https://gazebosim.org
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Joint out of control when close to its limits #165

Open lklimkiewicz7 opened 1 year ago

lklimkiewicz7 commented 1 year ago

I'm pretty new to ROS and may not understand something basic, but I have following problem:

I have a simulated arm, which has limits on every joint and I'm using ForwardCommandController to control it. Unfortunately when I command some joint to move to its limit or near it, there are chances that it will get stuck there. Then I can still control other joints and sometimes this dead joint comes to live again - probably because it gets a little bit farther from its limit due to other movements.

Is this behavior expected or I'm doing something wrong? How to allow controlling joints which are near they limits?

I don't have experience with real robots and I'm not sure whether it's gz_ros2_control or ros2_control issue.

mrjogo commented 6 months ago

I also just ran into this issue of joints getting "stuck" if they are commanded to their limit (presumably because overshoot goes past the limit). To reproduce (on Humble):

ros2 launch ign_ros2_control_demos gripper_mimic_joint_example.launch.py
# in another terminal
ros2 topic pub -1 /gripper_controller/commands std_msgs/msg/Float64MultiArray '{data: [0.39]}'
ros2 topic pub -1 /gripper_controller/commands std_msgs/msg/Float64MultiArray '{data: [0.0]}'

(in this case it's commanding past the joint limit to illustrate the issue) The gripper will close with the first /gripper_controller/commands command and won't open with the second.

azeey commented 6 months ago

This is similar to https://github.com/gazebosim/gz-sim/issues/1684 which is caused by https://github.com/dartsim/dart/issues/1683 and fixed by https://github.com/dartsim/dart/pull/1774 and released in DART 6.13.1. That version of DART will soon be available on packages.osrfoundation.org for Gazebo Harmonic.

christophfroehlich commented 3 months ago

I'm tempted to close this issue as it seems to be not related with gz_ros2_control but with gz_sim itself.

christophfroehlich commented 1 month ago

I'll reopen this, as it got reported again and it seems that there is no fix for Fortress. (@azeey?)

azeey commented 1 month ago

I'll reopen this, as it got reported again and it seems that there is no fix for Fortress. (@azeey?)

Yeah, this has resurfaced in gz-sim as well (see https://github.com/gazebosim/gz-sim/issues/1684#issuecomment-2201224648). It looks like the behavior depends on the commanded value.

Also, unfortunately, the fix cannot be backported to Fortress since we use the version of DART in Ubuntu Focal/Jammy, which don't receive any updates, and the fix actually needs to go into DART.