话题模型：

如何自定义话题消息 

1.定义msg文件

2.在package.xml中添加功能包依赖

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

 3.在CMakeList.txt文件中添加编译选项

4.编译生成语言的相关文件 

头文件换成你在msg文件夹中创建的文件，在catkin_make编译之后，在devel/inlcude里面会生成.h文件

 将编译规则加入到cMakeLists.txt

add_executable(person_publisher src/person_publisher.cpp)
target_link_libraries(person_publisher ${catkin_LIBRARIES})
add_dependencies(person_publisher ${PROJECT_NAME}_generate_messages_cpp)add_executable(person_subscriber src/person_subscriber.cpp)
target_link_libraries(person_subscriber ${catkin_LIBRARIES})
add_dependencies(person_subscriber ${PROJECT_NAME}_generate_messages_cpp)

创建一个发布者节点，发布一个话题：

/***********************************************************************
Copyright 2020 GuYueHome (www.guyuehome.com).
***********************************************************************//*** 该例程将发布/person_info话题，自定义消息类型learning_topic::Person*/#include <ros/ros.h>
//改为添加对应的头文件
#include "learning_topic/Person.h" //#include <geometry_msgs/Twist.h>int main(int argc, char **argv)
{// ROS节点初始化，定义新的节点名字ros::init(argc, argv, "person_publisher");//ros::init(argc,argv,"velocity_publisher");// 创建节点句柄ros::NodeHandle n;// 创建一个Publisher，发布名为/person_info的topic，消息类型为learning_topic::Person，队列长度10ros::Publisher person_info_pub = n.advertise<learning_topic::Person>("/person_info", 10);//ros::Publisher turtle_vel_pub = n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel",10);// 设置循环的频率，频率为1Hzros::Rate loop_rate(1);int count = 0;while (ros::ok()){// 初始化learning_topic::Person类型的消息learning_topic::Person person_msg;person_msg.name = "Tom";person_msg.age  = 18; person_msg.sex  = learning_topic::Person::male;//宏调用/*geometry_msgs::Twist vel_msg;vel_msg.linear.x=2.0;vel_msg.angular.z=1.0;*/// 发布消息person_info_pub.publish(person_msg);//turtle_vel_pub.publish(vel_msg);ROS_INFO("Publish Person Info: name:%s  age:%d  sex:%d", person_msg.name.c_str(), person_msg.age, person_msg.sex);//注意：字符串形式的输出：c_str()// 按照循环频率延时loop_rate.sleep();}return 0;
}

 创建一个订阅者节点，接收刚才相同话题类型的消息

/***********************************************************************
Copyright 2020 GuYueHome (www.guyuehome.com).
***********************************************************************//*** 该例程将订阅/person_info话题，自定义消息类型learning_topic::Person*/#include <ros/ros.h>
#include "learning_topic/Person.h"
//#include <turtlesim/Pose.h>// 接收到订阅的消息后，会进入消息回调函数
void personInfoCallback(const learning_topic::Person::ConstPtr& msg)
//void poseCallback(const turtlesim::Pose::ConstPtr& msg)//指针
{// 将接收到的消息打印出来ROS_INFO("Subcribe Person Info: name:%s  age:%d  sex:%d", msg->name.c_str(), msg->age, msg->sex);//ROS_INFO("Turtle pose: x:%0.6f,y:%0.6f",msg->x,msg->y); 
}int main(int argc, char **argv)
{// 初始化ROS节点ros::init(argc, argv, "person_subscriber");//ros::init(argc,argv,"pose_subscriber");// 创建节点句柄ros::NodeHandle n;// 创建一个Subscriber，订阅名为/person_info的topic，注册回调函数personInfoCallbackros::Subscriber person_info_sub = n.subscribe("/person_info", 10, personInfoCallback);//ros::Subscriber pose_sub=n.subscribe("/turtle1/pose",10,poseCallback);// 循环等待回调函数ros::spin();return 0;
}
c