ubuntu16.04+kientic reports an error when running URDF+Gazebo integration;
unknown macro name: xacro:cylinder_inertial_matrix None None
when processing file: /media/bn/B64A68EA4A68A937/extend_ros/demo05_ws/src/urdf02_gazebo/urdf/car.urdf.xacro
Invalid <param> tag: Cannot load command parameter [robot_description]: command [/opt/ros/kinetic/lib/xacro/xacro /media/bn/B64A68EA4A68A937/extend_ros/demo05_ws/src/urdf02_gazebo/urdf/car.urdf.xacro] returned with code [2].
Param xml is <param command="$(find xacro)/xacro $(find urdf02_gazebo)/urdf/car.urdf.xacro" name="robot_description"/>
The traceback for the exception was written to the log file
Add <xacro:include filename="head.xacro" /> to the first line under the site <robot> tag to solve the problem