ros调用笔记本自带的摄像头，运行代码：
roslaunch usb_cam usb_cam-test.launch
出现找不到video0的问题，具体如下：
[ WARN] [1551505908.859622180]: Camera calibration file /home/shuaimou/.ros/camera_info/head_camera.yaml not found.
[ INFO] [1551505908.859670447]: Starting 'head_camera' (/dev/video0) at 640x480 via mmap (yuyv) at 30 FPS
[ERROR] [1551505908.859756248]: Cannot identify '/dev/video0': 2, No such file or directory
[ INFO] [1551505908.948543622]: Using transport "raw"
[usb_cam-2] process has died [pid 6543, exit code 1, cmd /home/shuaimou/catkin_ws/devel/lib/usb_cam/usb_cam_node __name:=usb_cam __log:=/home/shuaimou/.ros/log/449479f4-3caf-11e9-b61d-000c292447df/usb_cam-2.log].
log file: /home/shuaimou/.ros/log/449479f4-3caf-11e9-b61d-000c292447df/usb_cam-2*.log
不知道如何解决，还望大佬赐教。
