ros21讲学习-发布话题

topic发布

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创建功能包

cd /home/jo/workspace/catkin_ws/src

catkin_create_pkg learning_topic roscpp rospy std_msgs geometry_msgs turtlesim

代码：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,定义topic名字"velocity_publisher"，topic名字不可重复

ros::init(argc, argv, "velocity_publisher");

 

// 创建节点句柄，用句柄管理节点调用

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10

ros::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;

//发布数据

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("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

loop_rate.sleep();

}

 

return 0;

}

View Code

编译：

cmake中加入(注意找对位置，在build下面)

add_executable(velocity_publisher src/velocity_publisher.cpp)

target_link_libraries(velocity_publisher ${catkin_LIBRARIES})

cd ~/workspace/catkin_ws/src

catkin_make

source ~/workspace/catkin_ws/devel/setup.bash

执行：

终端1： roscore

终端2： rosrun turtlesim turtlesim_node

终端3： rosrun learning_topic velocity_publisher

现象：小乌龟画圆圈

Python版本：不用编译

直接在终端3：

python /home/jo/class/ros_21_tutorials/learning_topic/scripts/velocity_publisher.py

代码：

#!/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::Twist

import rospy
from geometry_msgs.msg import Twist

def 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10
    turtle_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 = 0.5
        vel_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

View Code

ros21讲学习-发布话题

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