在roslaunch运行的时候出现的问题解决：
Traceback (most recent call last):
File “/opt/ros/kinetic/lib/xacro/xacro”, line 33, in
xacro.main()
AttributeError: ‘module’ object has no attribute ‘main’
Invalid tag: Cannot load command parameter [robot_description]: command [/opt/ros/kinetic/lib/xacro/xacro --inorder ‘/home/ma/catkin_ws1/src/car-3/robot_description/urdf/car_body.urdf.xacro’] returned with code [1].
Param xml is
The traceback for the exception was written to the log file
解决方法：
安装xacro文件
github地址：
https://github.com/ros/xacro/tree/kinetic-devel
http://wiki.ros.org/xacro
catkin_make编译以后重新运行roslaunch。