【RK3399Pro学习笔记】六、ROS发布者Publisher的编程实现

如何实现一个发布者

初始化ROS节点；
向ROS Master注册节点信息，包括发布的话题名和话题中的消息类型；
创建消息数据；
按照一定频率循环发布消息。

C++

创建功能包

cd ~/catkin_workspace/src
catkin_create_pkg learning_topic roscpp rospy std_msgs geometry_msgs turtlesim

编写程序

nano ~/catkin_workspace/src/learning_topic/src/velocity_publisher.cpp

/***********************************************************************
Copyright 2020 GuYueHome (www.guyuehome.com).
***********************************************************************//*** 该例程将发布turtle1/cmd_vel话题，消息类型geometry_msgs::Twist*/#include <ros/ros.h>
#include <geometry_msgs/Twist.h>int main(int argc, char **argv)
{// ROS节点初始化ros::init(argc, argv, "velocity_publisher");// 创建节点句柄ros::NodeHandle n;// 创建一个Publisher，发布名为/turtle1/cmd_vel的topic，消息类型为geometry_msgs::Twist，队列长度10ros::Publisher turtle_vel_pub = n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel", 10);// 设置循环的频率ros::Rate loop_rate(10);int count = 0;while (ros::ok()){// 初始化geometry_msgs::Twist类型的消息geometry_msgs::Twist vel_msg;vel_msg.linear.x = 0.5;vel_msg.angular.z = 0.2;// 发布消息turtle_vel_pub.publish(vel_msg);ROS_INFO("Publish turtle velocity command[%0.2f m/s, %0.2f rad/s]", vel_msg.linear.x, vel_msg.angular.z);// 按照循环频率延时loop_rate.sleep();}return 0;
}

配置CMakeLists.txt

nano ~/catkin_workspace/src/learning_topic/CMakeLists.txt

在Build内，Install前加入

add_executable(velocity_publisher src/velocity_publisher.cpp)
target_link_libraries(velocity_publisher ${catkin_LIBRARIES})

设置需要编译的代码和生成的可执行文件；
设置链接库；
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编译并运行发布者

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 turtlesim turtlesim_node
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_topic velocity_publisher# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rqt_graph

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python

创建并编写脚本

cd ~/catkin_workspace/src/learning_topic
mkdir scripts
cd ~/catkin_workspace/src/learning_topic/scripts
nano velocity_publisher.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-########################################################################
####          Copyright 2020 GuYueHome (www.guyuehome.com).          ###
######################################################################### 该例程将发布turtle1/cmd_vel话题，消息类型geometry_msgs::Twistimport rospy
from geometry_msgs.msg import Twistdef velocity_publisher():# ROS节点初始化rospy.init_node('velocity_publisher', anonymous=True)# 创建一个Publisher，发布名为/turtle1/cmd_vel的topic，消息类型为geometry_msgs::Twist，队列长度10turtle_vel_pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)#设置循环的频率rate = rospy.Rate(10) while not rospy.is_shutdown():# 初始化geometry_msgs::Twist类型的消息vel_msg = Twist()vel_msg.linear.x = 0.5vel_msg.angular.z = 0.2# 发布消息turtle_vel_pub.publish(vel_msg)rospy.loginfo("Publsh turtle velocity command[%0.2f m/s, %0.2f rad/s]", vel_msg.linear.x, vel_msg.angular.z)# 按照循环频率延时rate.sleep()if __name__ == '__main__':try:velocity_publisher()except rospy.ROSInterruptException:pass

运行

sudo chmod +x ~/catkin_workspace/src/learning_topic/scripts/velocity_publisher.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 turtlesim turtlesim_node
# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rosrun learning_topic velocity_publisher.py# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rqt_graph

在这里插入图片描述