Workspace for ROS

Reference resources
ROS official wiki— understand ROS node
ROS official wiki— understand ROS topic of conversation
ROS official wiki— understand ROS Service and parameters

In front of
ROS Logical view of

ROS Introduction to workspace

ROS Your workspace provides predefined management patterns . The schematic diagram of the workspace is as follows ：

The figure includes two package, It is divided into orange and green , parallelogram Represents a code file , Square box Representative directory .

ROS The content of the workspace is divided into 4 class ：
- src： Deal with the most folders , Save all the code , Each subfolder is a pakage, There will be more details later
- build： Intermediate compilation file , Unless something strange happens at compile time bug, I don't care
- devel： All generated exec/.py The catalog of , It's also ROS The system guides the directory of packages written by itself , There will be more details later
- install： When it can be published , The directory where the program is saved

src Catalog

src Each folder in the directory represents a package, Every pakage Multiple executables can be generated , Each executable is a ROS node .
Every package Contains the following ：

• include： Store the prepared header file , stay CMakeLists.txt Specify... When adding include/*.h
• src： Save the authored source file , stay CMakeLists.txt Specify... When adding include/*.cpp
• srv（ Optional ）： Service agreement documents *.src Where to save , coordination CMakeLists.txt Of add_service_files() Use , Write the file name directly , Don't prefix
• msg（ Optional ）： Service agreement documents *.msg Where to save , coordination CMakeLists.txt Of add_message_files() Use , Write the file name directly , Don't prefix

devel Catalog

This directory is usually not separate , but ROS To support c++/Python Two outputs , So put it in a separate folder , And the default is ROS System boot file . Specific include ：
-setup.sh/.zsh/.bash： By different shell Called script ,source Right after ROS System The current workspace is guided in , It can be used later rosrun/roscd/… And so on package.
-local_setup.sh/.zsh/.bash： Used to call... In the current directory setup.sh
-__setup__util.py： Be similar to setup.sh, But for guiding python load
-env.sh： Environment settings for the current workspace , There is no need to manually call
-include：C++ Header Directory
-lib：c++ Compile the generated 、python Code and configuration file directory

• [pkg*]：c++ The output directory of the executable , Press package Folder split
• [pkgconfig]：C++ External boot configuration for , Used when it is dependent on other libraries , Below is each package Provides *.pc The configuration file
• python3：python Output file directory , Provided below site-package, Available python External call

Create a workspace

Create directory manually

source /opt/ros/noetic/setup.sh  #  This item can be added to ~/.bashrc, You don't need to call every time 
cd ~
mkdir catkin_ws
cd catkin_ws
mkdir src #  Create a code directory under the workspace 

establish package

After the following code is executed , Will press ROS Logical compilation code of workspace , But the directory is empty , Then it will be created directly build/devel/… Such as catalog , And add the corresponding configuration file

cd src
catkin_create_pkg test std_msgs #  Create a package test, Dependent library is std_msgs
cd ~/catkin_ws/
catkin_make #  Will compile normally , But no compiled code , Therefore, no executable program will be generated 
            #  Must be in ROS The root directory of the workspace calls 

catkin_cmake It's a compound command , Equivalent to

$ mkdir build
$ cd build
$ cmake ../src
$ make

Additional information

If you add or remove package, Be sure to carry out

$ catkin_make --force-cmake

If this command is invalid , Just delete build Catalog , Completely re execute .

follow-up

Reference resources
ROS Of Topic Create and run samples
ROS Service creation and running example of
Create the first program .