如何用rospy实现小海龟走正方形

您可以使用以下代码实现小海龟走正方形：

import rospy
from geometry_msgs.msg import Twist
from turtlesim.msg import Pose

def move_square():
    rospy.init_node('move_square', anonymous=True)
    velocity_publisher = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)
    pose_subscriber = rospy.Subscriber('/turtle1/pose', Pose, pose_callback)
    vel_msg = Twist()

    # Set the linear velocity in the x-axis
    vel_msg.linear.x = 1

    # Set the angular velocity in the z-axis
    vel_msg.angular.z = 0

    # Set the rate to 10 Hz
    rate = rospy.Rate(10)

    # Move the turtle in a square
    for i in range(4):
        # Move forward for 2 seconds (10 * 2 = 20 times)
        for j in range(20):
            velocity_publisher.publish(vel_msg)
            rate.sleep()

        # Stop the turtle for 1 second (10 * 1 = 10 times)
        vel_msg.linear.x = 0
        for j in range(10):
            velocity_publisher.publish(vel_msg)
            rate.sleep()

        # Turn the turtle for 2 seconds (10 * 2 = 20 times)
        vel_msg.linear.x = 0
        vel_msg.angular.z = 1
        for j in range(20):
            velocity_publisher.publish(vel_msg)
            rate.sleep()

        # Stop the turtle for 1 second (10 * 1 = 10 times)
        vel_msg.angular.z = 0
        for j in range(10):
            velocity_publisher.publish(vel_msg)
            rate.sleep()

    # Stop the turtle
    vel_msg.linear.x = 0
    velocity_publisher.publish(vel_msg)

def pose_callback(pose):
    # Print the turtle's pose
    rospy.loginfo("Turtle pose: x=%f, y=%f", pose.x, pose.y)

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

这个程序使用 rospy 发布和订阅 ROS 主题来控制小海龟的运动。在程序中，我们首先初始化节点并创建一个发布器和一个订阅器。然后，我们设置小海龟的线速度和角速度，并使用循环来让小海龟走正方形。在每个循环中，我们发布速度消息并等待一段时间，然后停止小海龟并等待一段时间，然后再旋转小海龟并等待一段时间。最后，我们停止小海龟并退出程序。