当使用摄像头遇到如下问题：[usb_cam-1] process has died [pid 12288, exit code 127, cmd /opt/ros/indigo/lib/usb_cam/usb_cam_node __name:=usb_cam __log:=/home/sanstyle/.ros/log/783945ac-c7e3-11e6-bddb-4437e6444bf6/usb_cam-1.log].
log file: /home/sanstyle/.ros/log/783945ac-c7e3-11e6-bddb-4437e6444bf6/usb_cam-1*.log
可能是ros-indigo-usb-cam的问题，需要先卸载后再安装
sudo apt-get remove ros-indigo-usb-cam
sudo apt-get install ros-indigo-usb-cam