<?xml version="1.0"?> <robot xmlns:xacro="http://www.ros.org/wiki/xacro" > <joint name="imu_joint" type="fixed"> <parent link="chassis"/> <child link="robot_imu"/> <origin xyz="${chassis_length/2 - 0.15285} 0 0" rpy="0 0 0"/> </joint> <link name="robot_imu"> </link> <gazebo reference="robot_imu"> <material>Gazebo/Black</material> </gazebo> </robot>