#!/usr/bin/env python   turtlesim1.py
# Execute as a python script  
# Set linear and angular values of TurtleBot's speed and turning. 
import rospy				# Needed to create a ROS node
from geometry_msgs.msg import Twist    # Message that moves base

class ControlTurtlesim():
    def __init__(self):
        # ControlTurtlesim is the name of the node sent to the master
        rospy.init_node('ControlTurtlesim', anonymous=False)

		 # Message to screen
        rospy.loginfo(" Press CTRL+c to stop TurtleBot")

        # Keys CNTL + c will stop script   
        rospy.on_shutdown(self.shutdown)
        
	# Publisher will send Twist message on topic 
        # /turtle1/cmd_vel
       
        self.cmd_vel = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10) 
     
	     # Turtlesim will receive the message 10 times per second. 
        rate = rospy.Rate(10);   
	     # 10 Hz is fine as long as the processing does not exceed
        #   1/10 second.
        rospy.loginfo(" Set rate 10Hz")
        # Twist is geometry_msgs for linear and angular velocity
        move_cmd = Twist()
	     # Linear speed in x in meters/second is + (forward) or 
        # - (backwards)
        move_cmd.linear.x = 0.3	# Modify this value to change speed
	     # Turn at 0 radians/s
        move_cmd.angular.z = 0	
        # Modify this value to cause rotation rad/s

	     # Loop and TurtleBot will move until you type CNTL+c
        while not rospy.is_shutdown():
	         # publish Twist values to the Turtlesim node /cmd_vel
            self.cmd_vel.publish(move_cmd)
	         # wait for 0.1 seconds (10 HZ) and publish again
            rate.sleep()
                        
        
    def shutdown(self):
        # You can stop turtlebot by publishing an empty Twist message 
        rospy.loginfo("Stopping Turtlesim")
	
        self.cmd_vel.publish(Twist())
	     # Give TurtleBot time to stop
        rospy.sleep(1)
 
if __name__ == '__main__':
    try:
        ControlTurtlesim()
    except:
        rospy.loginfo("End of the trip for Turtlesim")