ROS knowledge points - definition and use of topic messages

Reference resources ：https://www.guyuehome.com/34659

One 、 Mr Into person.h The header file （1 Definition msg file ;2 stay package.xml Add Feature Pack dependencies to ;3 stay CMakeLists.txt Add compile options ;4 Compile and generate language related files ）
Two 、 Then configure the header file （1 establish publisher and subscriber;2CMakeLists.txt Add dependency... To .）

bug1：package.xml

Compile dependencies , Dependent dynamic generation message Function pack message_generation

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

stay package.xml The above compile and run dependencies must be written in , Otherwise, the following error will be reported ：

catkin_package() DEPENDS on the catkin package ‘message_runtime’ which must therefore be listed as a run dependency in the package.xml

bug2：CMakeLists.txt

find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
)

Add compilation dependent function packs message_generation

add_message_files(FILES Person.msg)
generate_messages(DEPENDENCIES std_msgs)

It's a .msg File is compiled into configuration items of different program files （ There is no such sentence ,catkin_make when , stay devel/include The following will not generate .h file ,Person.h）

catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES learning_msg
  CATKIN_DEPENDS roscpp rospy std_msgs message_runtime
#  DEPENDS system_lib
)

stay catkin_package() Create run dependencies inside

bug3：catkin_make

msg The first letter of the document should be capitalized ,Person.msg
catkin_make Then it will be under this path devel/include/ Function pack Generate Person.h

bug4：add_dependencies()

add_dependencies(person_publisher ${PROJECT_NAME}_generate_messages_cpp)

Because some code is generated dynamically , So we need to make the executable file and the dynamically generated program have dependencies , This sentence is used to follow the passage just now .msg File generated header file (person.h) To make links . This sentence must be added to link to a custom message .

bug5： Again catkin_make Report errors

This is because the header file function package referenced in the directly copied code is named learning_topic, So change two cpp The content is as follows ：

#include "learning_msg/Person.h"

And it corresponds to learning_topic:: It should also be changed to learning_msg::