1. [.launch] is neither a launch file in package
解决：export ROS_PACKAGE_PATH=￥ROS_PACKAGE_PATH:~/catkin_ws/src
2. cannot locate node [ur_driver] of package [ur_mordern_driver/ur_driver]
解决：source ~/catkin_ws/devel/setup.bash加入~/.bashrc文件中，然后在终端source ~/.bashrc
3. "roscore"尚未安装，但实际已安装
解决：source /opt/ros/kinetic/setup.bash加入~/.bashrc文件中，然后在终端source ~/.bashrc
4. echo $ROS_PACKAGE_PATH查看ROS环境变量