话题消息的定义与使用

在catkin_ws/src/learning_logic文件夹中创建Msg文件夹

如何自定义话题消息

Person.msg

string name
uint8 sex
uint8 age

uint8 unknown=0
uint8 male=1
uint8 female=2

在package.xml中添加功能包依赖

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

在CMakeList.txt中添加编译选项

find_package(... message_generation)

Declare ROS messages, services and actions中添加
add_message_files(
FILES
Person.msg
)

generate_messages(
DEPENDENCIES
std_msgs
)

catkin_package(... message_runtime)(给注释取消并且加上)

编译并且运行

cd ~/catkin_ws
catkin_make
(会在devel/include/learning_topic中生成.h文件)

person_publisher.cpp

点击查看代码

#include <ros/ros.h>
#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<learning_topic::Person>("/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;
		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;
}

person_subscriber.cpp

点击查看代码

#include <ros/ros.h>
#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;
}

配置CMakeLists.txt中编译规则

加在build中：
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)

编译并且运行发布者和订阅者

cd ~/catkin_ws
catkin_make
source devel/setup.bash
roscore
rosrun learning_topic person_subscriber
rosrun learning_topic person_publisher