topic发布
-----------------------------------------------------------------
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; }
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
原文：https://www.cnblogs.com/polipolu/p/12944847.html