move.py

#!/usr/bin/env python 
import rospy  
from geometry_msgs.msg import Twist  
from sensor_msgs.msg import LaserScan  
from time import time  
   
def laser_scan_callback(data):  
    print data.ranges  
   
def read_laser_scan_data():  
    rospy.Subscriber('scan',LaserScan,laser_scan_callback)  
   
def move_motor(fwd,ang):  
    pub = rospy.Publisher('cmd_vel',Twist,queue_size = 10)  
    mc = Twist()  
    mc.linear.x = fwd 
    mc.angular.z = ang  
    pub.publish(mc)  
   
if __name__ == '__main__':  
    rospy.init_node('example_script',anonymous=True)  
   
    start_time = time()  
    duration = 5 #in seconds  
   
    forward_speed = 1  
    turn_speed = 1  
   
    while time()<start_time+duration:  
        try:  
            read_laser_scan_data()  
            move_motor(forward_speed,turn_speed)  
        except rospy.ROSInterruptException:  
            pass  
    else:  
        move_motor(0,0)