triangle.py

#!/usr/bin/python3

import rospy
import math
from geometry_msgs.msg import Twist

pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=1)
rospy.init_node('turtle_rare_go_in_a_square', anonymous=False)
rate = rospy.Rate(1)
move = Twist()
go_straight = 2*(math.pi)*90/360
equilateral_angle = 2*(math.pi)*120/360


def triangle():

    while not rospy.is_shutdown():
        move.linear.x = 0.0
        move.angular.z = 0.0
        pub.publish(move)
        rate.sleep()
        
        for _ in range(4):
            move.linear.x = go_straight
            move.angular.z = 0.0
            pub.publish(move)
            rate.sleep()

            move.linear.x = 0.0
            move.angular.z = equilateral_angle
            pub.publish(move)
            rate.sleep()

        break    


if __name__ == '__main__':
    try:
        triangle()
    except rospy.ROSInterruptException:
        pass