ROS学习（四）--2.自定义话题案例

目录

一、自定义话题信息

1.创建msg文件

2.在 package.xml中添加功能依赖包

3.在CMakeLists.txt添加编译选项

​编辑

4.编译生成语言相关文件

二、应用此自定义话题

1.在话题功能包的src目录下创建person_publisher.cpp

2.创建person_subscriber.cpp

3.配置功能包的CMakeLists.txt中的编译规则，build栏中

​编辑  4.编译

5.运行 

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实现内容：自定义话题内容，并且发布和订阅自定义话题中的信息

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 ROS发布话题与订阅话题https://download.csdn.net/download/m0_56451176/86398720?spm=1001.2014.3001.5503

一、自定义话题信息

1.创建msg文件

cd ~/catkin_ws/src/learning_topic
mkdir msg
cd msg
touch Person.msg
gedit Person.msg

 Person.msg内容如下：

string name    #字符串对象name
uint8 sex      
uint8 age

uint8 unknown = 0	#宏定义
uint8 male = 1
uint8 female = 2

注：定义姓名、性别、年龄

宏定义：未知、男、女 

2.在 package.xml中添加功能依赖包

在话题功能包的package.xml中添加功能包的编译依赖和运行依赖

message_generation #动态产生message
message_runtime		#运行依赖

  

3.在CMakeLists.txt添加编译选项

find_package(....... message_generation)				

add_message_files(FILES Person.msg)		#将msg文件加入编译
generate_messages(DEPENDENCIES std_msgs)#依赖，在messages，services栏中加

catkin_package(...... message_runtime)	#依赖若被注释要取消

4.编译生成语言相关文件

cd ~/catkin_ws
catkin_make

---

二、应用此自定义话题

1.在话题功能包的src目录下创建person_publisher.cpp

cd ~/catkin_ws/src/learning_topic/src
touch person_publisher.cpp
gedit person_publisher.cpp

person_publisher.cpp内容如下 

//该例程将发布/person_info话题，自定义消息类型learning_topic::Person
#include 
#include "learning_topic/Person.h"
int main(int argc, char **argv){
    // ROS节点初始化
    ros::init(argc, argv, "person_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10
    ros::Publisher person_info_pub = n.advertise("/person_info", 10);
    // 设置循环的频率
    ros::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;		//定义Person对象
		person_msg.name = "Tom";
		person_msg.age  = 18;
		person_msg.sex  = learning_topic::Person::male;
        // 发布消息
		person_info_pub.publish(person_msg);
       	ROS_INFO("Publish Person Info: name:%s  age:%d  sex:%d", 
		person_msg.name.c_str(), person_msg.age, person_msg.sex);
        // 按照循环频率延时
        loop_rate.sleep();
    }
    return 0;
}

2.创建person_subscriber.cpp

cd ~/catkin_ws/src/learning_topic/src
touch person_subscriber.cpp
gedit person_subscriber.cpp

 person_subscriber.cpp内容如下：

//该例程将订阅/person_info话题，自定义消息类型learning_topic::Person
#include 
#include "learning_topic/Person.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){
    // 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);
}

int main(int argc, char **argv){
    // 初始化ROS节点
    ros::init(argc, argv, "person_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personInfoCallback
    ros::Subscriber person_info_sub = n.subscribe("/person_info", 10, personInfoCallback);
    // 循环等待回调函数
    ros::spin();
    return 0;
}

3.配置功能包的CMakeLists.txt中的编译规则，build栏中

add_executable(person_publisher src/person_publisher.cpp)					#运行
target_link_libraries(person_publisher ${catkin_LIBRARIES})					#库连接
add_dependencies(person_publisher ${PROJECT_NAME}_generate_messages_cpp)	#连接依赖，与自定义消息连接

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

4.编译

cd ~/catkin_ws
catkin_make
source ~/catkin_ws/devel/setup.bash

5.运行 

roscore

source ~/catkin_ws/devel/setup.bash
rosrun learning_topic person_publisher

source ~/catkin_ws/devel/setup.bash
rosrun learning_topic person_subscriber

  

注：1.订阅者可以会有一点延迟

2.当发布者和订阅者已经建立了连接，ros master就不再必要，ros master只负责为两者建立连接，若有其他连接才再需要

详细内容请看：ROS学习（四）发布者与订阅者