【RK3399Pro学习笔记】八、ROS话题消息的定义与使用

目录

• 自定义话题消息
• • 定义msg文件
  • 在package.xml中添加功能包依赖
  • 在CMakeLists.txt添加编译选项
  • 编译
  • 结果
• 使用
• • C++
  • • 编写程序
    • • person_publisher.cpp
      • person_subscriber.cpp
    • 配置CMakeLists.txt
    • 编译并运行
  • python
  • • 编写程序
    • • person_publisher.py
    • 运行

平台：华硕 Thinker Edge R 瑞芯微 RK3399Pro
固件版本： Tinker_Edge_R-Debian-Stretch-v1.0.13-20210702

---

记录自【古月居】古月·ROS入门21讲 | 一学就会的ROS机器人入门教程 —— 古月居GYH P12 12.话题消息的定义与使用

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

 
#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

 
#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)

1. 设置需要编译的代码和生成的可执行文件；
2. 设置链接库；
3. 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