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libgazebo_ros_planar_move low rotational velocity

asked 2020-10-22 02:32:31 -0600

robotlab gravatar image

updated 2020-10-22 03:29:51 -0600

Hi,

I have a working omni-directional mobile robot in Gazebo 9/11 and ROS Melodic/Noetic. I use libgazebo_ros_planar_move to control the robot. Everything is working but when doing a rotation in place the rotational velocity is very low in Gazebo. If I for instance publish 3 rad/s to cmd_vel with RQT Robot Steering it still takes almost 30 sec to make one full rotation. Gazebo is running at 1x real-time factor, so there is no delay on that end. Is this a bug or something I am missing? I have been looking through the source of the planar move plugin, but nothing obvious here to me that should make it slow down.

Attached image shows the cmd_vel sent and the returned calculated odom from the plugin in Gazebo. Odom's angular velocity caps at around 0.22, while 3.0 is sent to cmd_vel. I expect both are represented in rad/s.

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answered 2020-10-22 04:28:25 -0600

nlamprian gravatar image

The planar move plugin works by assigning velocities directly to the model. Ie. the wheels do not move. I can only assume these commands are restricted by the friction on the wheels as they are dragged while moving. Try lowering the friction of the wheel links, and see what happens.

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I will try that, but from what I understood about the planar move plugin is that it disables physics for the robot anyway, so friction parameters are disregarded hence there is no dragging of the wheels. I can basically make the robot levitate, and it would behave the same way.

robotlab gravatar imagerobotlab ( 2020-10-25 05:42:38 -0600 )edit

Additionally, the translational movement is correct moving at expected 1 m/s 🤔

robotlab gravatar imagerobotlab ( 2020-10-25 06:06:22 -0600 )edit
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Asked: 2020-10-22 02:32:31 -0600

Seen: 31 times

Last updated: Oct 22