ROS 에서 timed 실현out_and_back 기능

http://blog.csdn.net/scliu12345/article/details/44538927
#include "ros/ros.h"
//#include "std_msgs/String.h"//geometry_msgs
#include "geometry_msgs/Twist.h"//  elocity space  
#include "math.h"

#include <sstream>
#include <iostream>

int main(int argc, char **argv)
{
	ros::init(argc,argv,"out_and_back");//    “out_and_back”
	ros::NodeHandle n;//        
    ros::Publisher cmd_vel_pub=n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel",1000);//  /cmd_vel       geometry_msgs::Twist  
	int rate=50;//      
	ros::Rate loop_rate(rate);//    50Hz，            Rate::sleep()      ，              
	
	//     
    float linear_speed=0.2;//      0.2m/s
    float goal_distance=1.0;//    1.0m
    float linear_duration=goal_distance/linear_speed;//     = 5s
    float angular_speed=1.0;//   1.0rad/s
    float goal_angle=M_PI;

	geometry_msgs::Twist move_cmd;//      
	move_cmd.linear.x=move_cmd.linear.y=move_cmd.linear.z=0;
	move_cmd.angular.x=move_cmd.angular.y=move_cmd.angular.z=0;

	
	int count=0;//      
    while(ros::ok())//    ctrl+C     
	{
        std::cout<<"Hello world:"<<"The "<<count+1<<"th circle!"<<"
";

		//    
		move_cmd.linear.x=linear_speed;
		int ticks=int(linear_duration*rate);
		for(int i=0;i<ticks;i++)
		{
			cmd_vel_pub.publish(move_cmd);
			loop_rate.sleep();
		}

		//     
		move_cmd.linear.x=0;
		cmd_vel_pub.publish(move_cmd);
		ros::Duration(1).sleep(); //  1s

		//  180 
		move_cmd.angular.z=angular_speed;//     
        ticks=int(goal_angle*rate);
		for(int i=0;i<ticks;i++)
		{
			cmd_vel_pub.publish(move_cmd);
			loop_rate.sleep();
		}
		
		//  
		move_cmd.angular.z=0;
		cmd_vel_pub.publish(move_cmd);
		ros::Duration(1).sleep(); 

		count++;
    }
	//   
	move_cmd.linear.x=0;
	move_cmd.angular.z=0;
	cmd_vel_pub.publish(move_cmd);
	ros::Duration(1).sleep(); 
	
	return 0;
}