ROS create workspace process

This article takes porting code as an example . The goal is to make a platform SDK Medium ROS The code part is picked out and transplanted to the workspace you created . Record the general process .

Catalog

1、 Create a workspace

2、 Compile workspace （ Optional ）

3、 Set the environment variable （ Optional ）

4、 Create Feature Pack

5、 Write source code 、 modify CMakeLists.txt file

6、 Compile function packs

7、 Enable node

1、 Create a workspace

mkdir -p pantilt_ws/src
cd pantilt_ws/src
catkin_init_workspace

pantilt_ws Folders are workspaces created ,src The folder is created later Function pack Source code .catkin_init_workspace Command is used to initialize the workspace , The order will be in src Generate one in the folder CMakeLists.txt The file of .

2、 Compile workspace （ Optional ）

This step is not necessary here , It can be put to the end . This step is only used here to explain that you can compile when the workspace is empty , in addition , To show how the workspace will change after running this command .

cd pantilt_ws
catkin_make

catkin_make In the workspace pantilt_ws  In the middle of devel、build These two folders ：

devel： Development space , Place executable files in the development process

build： Intermediate files generated during compilation

These two files and their contents are self generated by relevant instructions in the development process , We don't care .

3、 Set the environment variable （ Optional ）

If steps are not performed 2, Go straight to step 4  that will do . After compiling the workspace, you need to add the workspace to the environment variable , You can use the following instructions , Put the workspace devel Under folder setup.bash The path of the file is added to the environment variable .

source devel/setup.bash

The inconvenience of doing this is that you have to re run each time source once , We can add the following path directly to ~/.bashrc In file

open  ~/.bashrc file

gedit ~/.bashrc

Add a path

source ~/Desktop/pantilt_ws/devel/setup.bash

Save and exit .

4、 Create Feature Pack

The function package must be placed in the workspace src Under the folder , In addition, all source code must be placed in the function package . Create a template for the Feature Pack ：

catkin_create_pkg <package_name> [depend1] [depend2] [depend3] 

catkin_create_pkg The command is followed by the name of the Feature Pack , Function report name followed by dependency . 

Here I create a file called pantilt_ctl Function pack ：

cd pantilt_ws/src
catkin_create_pkg pantilt_ctl std_msgs rospy roscpp message_generation message_runtime

After the creation is successful pantilt_ws/src There will be one more pantilt_ctl And a folder named CMakeLists.txt The file of

stay pantilt_ctl  A new folder will be created  include and src Folders and  CMakeLists.txt and package.xml file .

package.xml  The beginning of the document is mainly to use xml The function of language recording is reported name 、 edition 、 Description and open source agreement Etc , then package.xml  It also includes Function package dependency Information . When creating the function package std_msg/roscpp/rospy The dependency package will be written here , If there are additional dependent function packages, you can manually add them .

CMakeLists.txt The file is mainly used to describe the Compilation Rules of the function package during compilation , That is, some compilation instructions , It uses CMake The grammar of . 

5、 Write source code 、 modify CMakeLists.txt file

If you write your own code, it's in the function pack  pantilt_ctl  Of src New under folder cpp Source file , stay include New under folder cpp The header file is enough .

Here, Yuntai will be officially SDK Copy the relevant files in the source code , And make the corresponding class name 、 Modification of path name, etc .

And then there's the modification  CMakeLists.txt The content of the document .

For example, I have only one read_write_node.cpp Of ROS Node source file , So you need to CMakeLists.txt Add the following two statements to the file ：

add_executable(read_write_node src/read_write_node.cpp)
target_link_libraries(read_write_node ${catkin_LIBRARIES})

add_executable The first parameter is the name of the generated executable , The second parameter is the code that needs to be compiled .

target_link_libraries Set the link library to generate executable files .

For other commands ,CMakeLists.txt There are corresponding comments in the document to explain the function of the command .

for example , If you want to add msg file （ Create... In the feature pack msg Folder , New msg All the papers are here ） If it works , Just add the following statement ;

find_package(catkin REQUIRED COMPONENTS
  ...
  message_generation
)

## Generate messages in the 'msg' folder
add_message_files(
  FILES
  your_msg_name.msg
)

## Generate added messages and services with any dependencies listed here
generate_messages(
  DEPENDENCIES
  std_msgs
)

catkin_package(
 ...
 message_runtime
)

• find_package Add the dependent function package .
• add_message_files It lists your msg file Name , In this way, the program will find the defined message interface when compiling , Then compile according to this interface , And generate the corresponding header file and put it in devel/include/[your_package_name]/[your_msg_name].h in ,cpp When used in the code, directly add the header file through the following code ：

#include "[your_package_name]/[your_msg_name].h"

• generate_messages Compilation generation is listed in msg Time dependence , Here is std_msgs.
• catkin_package Add msg Compile time dependencies , namely message_runtime.

Still need to be in package.xml Add function package dependencies to the file ：

  <build_depend>message_generation</build_depend>
  <exec_depend>message_runtime</exec_depend>

build_depend Is a compilation dependency , Dependencies required during program compilation .

exec_depend  Is the execution dependency , Dependencies needed when the program runs .

6、 Compile function packs

First go back to the directory of the workspace and execute the compilation  

cd pantilt_ws
catkin_make

Then set the environment variable

source pantilt_ws/devel/setup.bash

7、 Enable node

Use the command first roscore start-up rosmaster, Then open a new terminal to use rosrun The command enables nodes in the Feature Pack , The grammar is ：

rosrun [your_package_name] [you_node_name]

rosrun Followed by Function pack Name , The function package name is followed by this Nodes in the function package Name .

Such as ：

rosrun pantilt_ctl read_write_node