ROS古月程序 Arbotix+rviz仿真出现以下，是为什么？
问题遇到的现象和发生背景
问题相关代码，请勿粘贴截图 roslaunch mbot_description arbotix_mbot_with_camera_xacro.launch
运行结果及报错内容 [ERROR] [1643000623.020949668]: Failed to build tree: parent link [base_link] of joint [camera_joint] not found. This is not valid according to the URDF spec. Every link you refer to from a joint needs to be explicitly defined in the robot description. To fix this problem you can either remove this joint [camera_joint] from your urdf file, or add "" to your urdf file.
[robot_state_publisher-4] process has died [pid 5740, exit code 1, cmd /opt/ros/noetic/lib/robot_state_publisher/robot_state_publisher __name:=robot_state_publisher __log:=/home/fang/.ros/log/ffc2411e-7cd2-11ec-8ac7-7d8c5005e9e1/robot_state_publisher-4.log].
log file: /home/fang/.ros/log/ffc2411e-7cd2-11ec-8ac7-7d8c5005e9e1/robot_state_publisher-4*.log
[arbotix-2] process has died [pid 5738, exit code 1, cmd /home/fang/catkin_ws/src/arbotix_ros/src/arbotix_python/bin/arbotix_driver __name:=arbotix __log:=/home/fang/.ros/log/ffc2411e-7cd2-11ec-8ac7-7d8c5005e9e1/arbotix-2.log].
log file: /home/fang/.ros/log/ffc2411e-7cd2-11ec-8ac7-7d8c5005e9e1/arbotix-2*.log
[ERROR] [1643000625.260728101]: Failed to build tree: parent link [base_link] of joint [camera_joint] not found. This is not valid according to the URDF spec. Every link you refer to from a joint needs to be explicitly defined in the robot description. To fix this problem you can either remove this joint [camera_joint] from your urdf file, or add "" to your urdf file.