ROS 2 Migration: Diff drive

Overview

This pages describes the changes the diff drive plugin in gazebo_plugins for ROS 2, including a migration guide.

Summary

• <publishWheelJointState> has been removed. Use the gazebo_ros_joint_state_publisher plugin instead.
• All SDF parameters are now snake_cased
• Use remapping argument to change default topics (cmd_vel and odom)

SDF parameters

ROS 1	ROS 2
leftJoint	left_joint
rightJoint	right_joint
wheelSeparation	wheel_separation
wheelDiameter	wheel_diameter
odometryFrame	odometry_frame
udpateRate	update_rate
wheelTorque	max_wheel_torque
wheelAcceleration	max_wheel_acceleration
publishOdom	publish_odom
commandTopic	<ros><remapping>cmd_vel:=custom_cmd_vel</remapping></ros>
odometryTopic	<ros><remapping>odom:=custom_odom</remapping></ros>
publishWheelJointState	❌

Example Migration

ROS1

    <model name='vehicle'>
      ...

      <joint name='left_wheel_joint' type='revolute'>
        ...
      </joint>

      <joint name='right_wheel_joint' type='revolute'>
        ...
      </joint>

      <plugin name='diff_drive' filename='libgazebo_ros_diff_drive.so'>
        <updateRate>500</updateRate>
        <leftJoint>left_wheel_joint</leftJoint>
        <rightJoint>right_wheel_joint</rightJoint>
        <wheelSeparation>1.25</wheelSeparation>
        <wheelDiameter>0.3</wheelDiameter>
        <wheelTorque>20</wheelTorque>
        <wheelAcceleration>1.0</wheelAcceleration>
        <commandTopic>custom_cmd_vel</commandTopic>
        <odometryTopic>custom_odom</odometryTopic>
        <odometryFrame>odom</odometryFrame>
        <publishWheelJointState>true</publishWheelJointState>
      </plugin>

    </model>

ROS2

    <model name='vehicle'>
      ...

      <joint name='left_wheel_joint' type='revolute'>
        ...
      </joint>

      <joint name='right_wheel_joint' type='revolute'>
        ...
      </joint>

      <!-- Use gazebo_ros_joint_state_publisher instead of publishWheelJointState -->
      <plugin name="joint_states" filename="libgazebo_ros_joint_state_publisher.so">
        <joint_name>right_wheel_joint</joint_name>
        <joint_name>left_wheel_joint</joint_name>
      </plugin>


      <plugin name='diff_drive' filename='libgazebo_ros_diff_drive.so'>
        <ros>
          <!-- Set namespace -->
          <namespace>/demo</namespace>

          <!-- Remap default topics -->
          <remapping>cmd_vel:=cmd_demo</remapping>
          <remapping>odom:=odom_demo</remapping>
        </ros>

        <!-- Replace camelCase elements with camel_case ones -->
        <update_rate>500</update_rate>
        <left_joint>left_wheel_joint</left_joint>
        <right_joint>right_wheel_joint</right_joint>
        <wheel_separation>1.25</wheel_separation>
        <wheel_diameter>0.3</wheel_diameter>
        <odometry_frame>odom</odometry_frame>

        <!-- wheelTorque and wheelAcceleration now have max_ prefix -->
        <max_wheel_torque>20</max_wheel_torque>
        <max_acceleration>1.0</max_acceleration>

      </plugin>

    </model>