【ROS】自定义消息类型

---

一、自定义msg文件

工程中由于自定义的msg或srv比较多，通常会单独把自定义的内容放入一个pkg。本节我们新建一个叫public_pkg的pkg。

1、创建工作空间与功能包

mkdir -p catkin_ws1/src
cd catkin_ws1/src
catkin_init_workspace
cd ~/catkin_ws1
catkin_make
catkin_make install
cd ~/catkin_ws1/src
catkin_create_pkg public_pkg std_msgs roscpp

2、自定义msg文件

cd public_pkg
mkdir msg
cd msg
touch CustomMsg.msg
gedit CustomMsg.msg

CustomMsg.msg内容如下：

string name
string gender
uint8 age
float64 hight

3、修改CMakeLists.txt

确保以下几项与本文相同

find_package(catkin REQUIRED COMPONENTS
  roscpp
  std_msgs
  message_generation
)
add_message_files(
  FILES
  CustomMsg.msg
)
generate_messages(
  DEPENDENCIES
  std_msgs
)
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES public_pkg
 CATKIN_DEPENDS roscpp std_msgs message_runtime
#  DEPENDS system_lib
)

4、修改xml

新增以下两行

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

5、编译

cd ~/catkin_ws1
catkin_make

编译完成后，devel目录下会生成include/public_pkg/CustomMsg.h, 此文件就是我们将要使用的真正的类型文件

二、自定义msg文件的使用

自然我们是在另一个pkg中使用刚刚定义的CustomMsg, 为此，新增一个pkg是必要的，取名custom_msg_publisher, 从名字可以看出，我们将发布一个CustomMsg类型的Topic。

1、新建pkg

cd ~/catkin_ws1/src
catkin_create_pkg custom_msg_publisher std_msgs roscpp public_pkg

依赖public_pkg
package.xml新增：

<build_depend>public_pkgbuild_depend>
<build_export_depend>public_pkgbuild_export_depend>
<exec_depend>public_pkgexec_depend>

2、新建publisher

在custom_msg_publisher/src下新建custom_msg_publisher_node.cpp

touch custom_msg_publisher_node.cpp
gedit custom_msg_publisher_node.cpp

custom_msg_publisher_node.cpp

#include "ros/ros.h"
#include "public_pkg/CustomMsg.h"
 
int main(int argc, char **argv)
{
     
    ros::init(argc, argv, "custom_topic");
    ros::NodeHandle n;
 
    ros::Publisher custom_pub = n.advertise<public_pkg::CustomMsg>("custom_topic", 100);
 
    ros::Rate loop_rate(1);

    while (ros::ok())
    {
     
        public_pkg::CustomMsg msg;
 
	msg.name="chaoren";
	msg.gender="male";
        msg.age = 100;
	msg.hight=999.999;
        ROS_INFO("%s %s %s %s %s %d %s %f", "student information: name:", msg.name.c_str(),"gender:",msg.gender.c_str(),"age:",msg.age,"hight:",msg.hight);
	
	custom_pub.publish(msg);
 
        ros::spinOnce();
 
        loop_rate.sleep();
    }
 
    return 0;
}

3、修改CMakeLists.txt

其实就是反注释以下3句，我在文件命名的时候就以默认的规范，就不需要再对命名进行修改了。

add_executable(${
     PROJECT_NAME}_node src/custom_msg_publisher_node.cpp)
add_dependencies(${
     PROJECT_NAME}_node ${
     ${
     PROJECT_NAME}_EXPORTED_TARGETS} ${
     catkin_EXPORTED_TARGETS})
target_link_libraries(${
     PROJECT_NAME}_node
  ${
     catkin_LIBRARIES}
)

4、编译

cd ~/catkin_ws1
catkin_make

三、运行

roscore 
cd catkin_ws1
source devel/setup.bash
rosrun custom_msg_publisher custom_msg_publisher_node