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After all, it still drifts.

Just edited my question. In the meanwhile I remove joint frictions, and the trolley doesn't drift anymore.

I've just modeled a trolley for my robot to pull around, however I can't make it stop drifting. I've added friction to the wheel joints, but it does not produce any effect.

I observe the same drift with the gazebo model 'Cart: front steering'.

The trolley is fully stopped at the beginning of the simulation, but then it starts to move. If I disable the trolley's base link gravity (only wheels remain affected by gravity), it won't move. But removing the effect of gravity on the trolley is not an acceptable solution for me.

Do you have any suggestions on how to make the trolley not drift?

Edit: After removing friction from wheel joints, the robot drifts less.

Edit2: As asked in the answer:

    <mass>5.0</mass>
    <inertia>
      <ixx>0.27</ixx>       <!-- for a box: ixx = 0.083 * mass * (y*y + z*z) -->
      <ixy>0.0</ixy>         <!-- for a box: ixy = 0 -->
      <ixz>0.0</ixz>         <!-- for a box: ixz = 0 -->
      <iyy>0.15</iyy>       <!-- for a box: iyy = 0.083 * mass * (x*x + z*z) -->
      <iyz>0.0</iyz>         <!-- for a box: iyz = 0 -->
      <izz>0.415</izz>       <!-- for a box: izz = 0.083 * mass * (x*x + y*y) -->
    </inertia>
  </inertial>

For the wheels:

  <inertial>
    <mass>0.1</mass>
    <inertia>
      <ixx>0.00001</ixx>
      <ixy>0</ixy>
      <ixz>0</ixz>
      <iyy>0.00001</iyy>
      <iyz>0</iyz>
      <izz>0.00001</izz>
    </inertia>
    <pose>0 0 0 0 0 0</pose>
  </inertial>

Hello!

I'm using Gazebo 5 and ROS jade on Ubuntu 14.0.2, from debs.

I'm developing a simulation of a self-balancing robot on Gazebo. I have based the plugin I'm using on gazebo_ros_diff_drive. The plugin maintains the robot always balanced, while listening for cmd_vel and publishing odom.

So far this small adaptation of gazebo_ros_diff_drive was pretty straighforward. However I've encountered some troubles when I try to spawn multiple robots. These problems do not occur on the original gazebo_ros_diff_drive.

In short, when I have multiple robots I'm not able to command the joints' velocities. It looks like that one of the multiple instantiated plugins takes over all of the robots. This does not happen with the original diff_drive.

example:

• spawn robot1 and robot2
• I observe robot1_plugin and robot2_plugin load() on the console.
• messages on topics robot1/cmd_vel and robot2/cmd_vel are received by their respective plugin
• randomly, either robot1_plugin or robot2_plugin will actually command both robots' joints

Any suggestion on how to debug this issue?