Unrealistic rotation behavior in Gazebo

jukindle commented 2 years ago

Please provide the following information:

OS: Ubuntu 20.04
ROS Distro: Noetic
Built from source or installed: apt-package
Package version: jackal_simulator 0.4.0, gazebo version 11.10.2

Expected behaviour By commanding a constant rotational velocity of 0.2rad/s, we would expect the robot to roughly rotate at 0.2rad/s about z-axis.

Actual behaviour Even though the robot rotates at the desired velocity, whenever the x-axis is axis-aligned with the diagonals in the x-y-plane, the robot seems to get stuck and the rotational velocity drops.

To Reproduce Provide the steps to reproduce:

Install the simulator by running sudo apt install ros-noetic-jackal-simulator
Launch the simulation running roslaunch jackal_gazebo jackal_world.launch

Command the robot to rotate on spot by running

rostopic pub -r 50 /jackal_velocity_controller/cmd_vel geometry_msgs/Twist "linear:
  x: 0.0
  y: 0.0
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: 0.2"

Other notes Video of the bug

According to this issue on the gazebo repository, this error seems to a bug in the friction pyramid implementation in gazebo. Two solutions were proposed: either change the friction model to cone, or increase the ERP to 0.6. Unfortunately, both solutions did not work for me and the only thing which helped is to drastically decrease the friction of the wheels. This results in unrealistic behavior as the robot would slip down slopes.

Do you see any possibility to solve this issue? I would love to use gazebo to test my software before deploying it to the real system, but with such unrealistically simulated skid-steer behavior, I am unable to do so.

peci1 commented 2 years ago

Yeah, it would be nice if somebody found the culprit for this. I definitely don't have time for that now, but feel free to ping me for a review if you find something ;)

peci1 commented 2 years ago

Could you maybe test it with other dynamics engines?

AlexGisi commented 4 months ago

The dart engine seems to be slightly better about this, but it is still a serious problem (Gazebo 11.11.0).

jackal / jackal_simulator

Unrealistic rotation behavior in Gazebo #18