1、首先看usb_cam： 

直接下载代码： 

进入创建好的工作空间：

cd ~/catkin_ws/src

git clonehttps://github.com/bosch-ros-pkg/usb_cam.git

然后退回到工作空间，编译代码：

cd~/catkin_ws

catkin_make

编译好之后，添加编译好的文件到环境变量：

sourcedevel/setup.bash

然后接下来测试usb_cam： 

先运行usb_cam节点：

rosrun usb_cam usb_cam_node

运行上面命令发现没有显示图像，只看到摄像头打开了。这是因为ros发布的topic是/usb_cam/image_raw。新打开一个终端，可以通过如下命令查看：

rostopic list

结果如下：

/rosout

/rosout_agg

/usb_cam/camera_info/usb_cam/image_raw

/usb_cam/image_raw/compressed

/usb_cam/image_raw/compressed/parameter_descriptions

/usb_cam/image_raw/compressed/parameter_updates

/usb_cam/image_raw/compressedDepth

/usb_cam/image_raw/compressedDepth/parameter_descriptions

/usb_cam/image_raw/compressedDepth/parameter_updates

/usb_cam/image_raw/theora

/usb_cam/image_raw/theora/parameter_descriptions

/usb_cam/image_raw/theora/parameter_updates

所以我们需要运行如下命令才可以看到图像：

rosrun image_view image_view image:=/usb_cam/image_raw

或者直接写launch文件，这样就不用一个终端运行node，一个终端看图像。新建usb_cam_test.launch：

<launch>

  <node name="usb_cam" pkg="usb_cam" type="usb_cam_node" output="screen" > 

    <param name="video_device" value="/dev/video0" /> 

    <param name="image_width" value="640" /> 

    <param name="image_height" value="480" /> 

    <param name="pixel_format" value="yuyv" /> 

    <param name="camera_frame_id" value="usb_cam" /> 

    <param name="io_method" value="mmap"/> 

  </node> 

  <node name="image_view" pkg="image_view" type="image_view" respawn="false" output="screen"> 

    <remap from="image" to="/usb_cam/image_raw"/> 

    <param name="autosize" value="true" /> 

  </node> 

</launch> 

其中字段的意义可按照字面理解，这里不再解释。 

然后终端直接运行：

roslaunch usb_cam usb_cam_test.launch