Programming implementation of ROS learning 2 publisher node

One . Overview of the topic release process ：

1. Create topic file .cpp/.py

2. compile .cpp The file needs to be compiled ,.py File is not required

3. Configure environment variables

4. Execute the release topic file

Two 、 The specific process is as follows ：

2.1 Create topic file

In the function package of the corresponding workspace Src Next , Create topic file , If you use c++ Write , Namely .cpp file , use py Writing is .py file .

The document consists of at least four parts ：

1. initialization ROS node

2. towards Ros Master Register node information , Including the topic name and topic message type （ROS Official or customized messages , How to view ros The message structure provided by the system is detailed in the document ：ROS Study 3 Custom message _m0_46093829 The blog of -CSDN Blog ）

3. Create message data （ Whether it's official or customized , In the message type file （.msg file ） Only variables and their data types are declared in , So you need to wait for variables here ......）

4. Circulate messages at a certain frequency

See the following for specific examples , This routine is Gu Yueju ROS21 Tell me an example .

2.2 compile

After saving the file , It's time to compile , Be careful cpp The file needs to be compiled ,py File is not required . The specific compilation method is ：

2.2.1 Set Compilation Rules

Go back to the function package directory , find CMakeLists.txt（ Set Compilation Rules ）, Then copy the following two lines of code to Install above

add_executable( File name  src/ File name .cpp)# Set the name of the code file to be compiled and the generated executable , That is, which program file is compiled into an executable file

target_link_libraries(velocity_publisher${catkin_LIBRARIES})# Set up link library , Put your executable file and ROS Make a link to the library in .

2.2.2 catkin_make

After modification, you can return to the root directory of the workspace to compile .catkin_make

2.3 Configure environment variables

Compile and then use source Configure an environment variable OK 了 .source devel/setup.bash

The specific compilation and configuration environment variables are in ROS Learning notes 1 In the introduction .

3、 ... and 、 Execute the topic file to publish the topic ：

rosrun Folder name file name