ROS话题消息是什么意思呢？怎样去使用ROS话题消息呢

自定义话题消息
定义msg文件
cd ~/catkin_workspace/src/learning_topic
mkdir msg
nano ~/catkin_workspace/src/learning_topic/msg/Person.msg
string name
uint8  age
uint8  sex
uint8 unknown = 0
uint8 male    = 1
uint8 female  = 2
在package.xml中添加功能包依赖
nano ~/catkin_workspace/src/learning_topic/package.xml
message_generation
message_runtime


在CMakeLists.txt添加编译选项
...
find_package(... message_generation)
...
add_message_files(FILES Person.msg)
generate_messages(DEPENDENCIES std_msgs)
...
catkin_package(... message_runtime)
...
nano ~/catkin_workspace/src/learning_topic/CMakeLists.txt




编译
cd ~/catkin_workspace
catkin_make
结果
可在~/catkin_workspace/devel/include/learning_topic下看到生成的Person.h
使用
C++
编写程序
person_publisher.cpp
nano ~/catkin_workspace/src/learning_topic/src/person_publisher.cpp
/***********************************************************************
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
#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;
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
nano ~/catkin_workspace/src/learning_topic/src/person_subscriber.cpp
/***********************************************************************
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
#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
nano ~/catkin_workspace/src/learning_topic/CMakeLists.txt
添加
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)
设置需要编译的代码和生成的可执行文件；
设置链接库；
添加依赖项。


编译并运行
cd ~/catkin_workspace
catkin_make
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roscore
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_topic person_publisher
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_topic person_subscriber
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rqt_graph



python
编写程序
person_publisher.py
nano ~/catkin_workspace/src/learning_topic/scripts/person_publisher.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-
########################################################################
####          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
import rospy
from learning_topic.msg import Person
def velocity_publisher():
# ROS节点初始化
    rospy.init_node('person_publisher', anonymous=True)
# 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
    person_info_pub = rospy.Publisher('/person_info', Person, queue_size=10)
#设置循环的频率
    rate = rospy.Rate(10)
    while not rospy.is_shutdown():
# 初始化learning_topic::Person类型的消息
     person_msg = Person()
     person_msg.name = "Tom";
     person_msg.age  = 18;
     person_msg.sex  = Person.male;
# 发布消息
        person_info_pub.publish(person_msg)
     rospy.loginfo("Publsh person message[%s, %d, %d]",
person_msg.name, person_msg.age, person_msg.sex)
# 按照循环频率延时
        rate.sleep()
if __name__ == '__main__':
    try:
        velocity_publisher()
    except rospy.ROSInterruptException:
        pass
nano ~/catkin_workspace/src/learning_topic/scripts/person_subscriber.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-
########################################################################
####          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
import rospy
from learning_topic.msg import Person
def personInfoCallback(msg):
    rospy.loginfo("Subcribe Person Info: name:%s  age:%d  sex:%d",
msg.name, msg.age, msg.sex)
def person_subscriber():
# ROS节点初始化
    rospy.init_node('person_subscriber', anonymous=True)
# 创建一个Subscriber，订阅名为/person_info的topic，注册回调函数personInfoCallback
    rospy.Subscriber("/person_info", Person, personInfoCallback)
# 循环等待回调函数
    rospy.spin()
if __name__ == '__main__':
    person_subscriber()
运行
sudo chmod +x ~/catkin_workspace/src/learning_topic/scripts/person_publisher.py
sudo chmod +x ~/catkin_workspace/src/learning_topic/scripts/person_subscriber.py
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roscore
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_topic person_publisher.py
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_topic person_subscriber.py
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rqt_graph