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ROS knowledge: how to realize camera access

2022-04-21 20:01:00 【Mr anhydrous】

One 、 explain

Connect the camera to ros System ,ROS Basic functions of ; What preparations are needed to access the camera ？

1） Prepare one USB The camera ;

2） Installed Ubuntu20.04、ros-neotic

Two 、 install usb_cam ROS Function pack

2.1 Generate workspace

mkdir -p ~/catkin_ws/src

cd ~/catkin_ws/src

2.2 from git-hub Download the driver package

Enter the created workspace ：

cd ~/catkin_ws/src
git clonehttps://github.com/bosch-ros-pkg/usb_cam.git

2.3 compile

Then go back to the workspace , Compile code ：

cd~/catkin_ws
catkin_make

After compiling , Add the compiled file to the environment variable ：

source  devel/setup.bash

2.4 test usb_cam

First run usb_cam node ：

rosrun usb_cam usb_cam_node

Run the above command and find that the camera is turned on . This is because ros released topic yes /usb_cam/image_raw.

Open a new terminal , Check it with the following command ：

rostopic list

give the result as follows ：

/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

2.5 Open a node to view the image

We need to run the following command to see the image ：

rosrun image_view image_view image:=/usb_cam/image_raw

2.6 use launch file open

direct writing launch file , So you don't need a terminal to run node, One terminal looks at the image . newly build 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>

Then the terminal runs directly ：