请用rospy让ros小海龟在(5.54,5.54), (5.54,8.54), (6.54,7.54), (5.54,6.54), (5.54,5.54)这几个坐标点中循环移动，要求是先转弯后直行

以下是一个简单的实现：

#!/usr/bin/env python

import rospy
from geometry_msgs.msg import Twist
from turtlesim.msg import Pose
from math import pow, atan2, sqrt

class TurtleBot:
    def __init__(self):
        # 初始化ROS节点和订阅者、发布者
        rospy.init_node('turtlebot_controller', anonymous=True)
        self.velocity_publisher = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)
        self.pose_subscriber = rospy.Subscriber('/turtle1/pose', Pose, self.update_pose)
        self.pose = Pose()

    def update_pose(self, data):
        self.pose = data
        self.pose.x = round(self.pose.x, 2)
        self.pose.y = round(self.pose.y, 2)

    def get_distance(self, goal_x, goal_y):
        distance = sqrt(pow((goal_x - self.pose.x), 2) + pow((goal_y - self.pose.y), 2))
        return distance

    def get_angle(self, goal_x, goal_y):
        angle = atan2(goal_y - self.pose.y, goal_x - self.pose.x)
        return angle

    def move_turtle(self):
        # 设置目标位置列表
        goal_positions = [(5.54,5.54), (5.54,8.54), (6.54,7.54), (5.54,6.54), (5.54,5.54)]
        # 设置线速度和角速度
        linear_speed = 0.5
        angular_speed = 0.5
        # 循环移动小海龟
        while not rospy.is_shutdown():
            for goal_x, goal_y in goal_positions:
                distance_tolerance = 0.1
                # 计算目标位置与当前位置的距离和角度差
                distance = self.get_distance(goal_x, goal_y)
                angle = self.get_angle(goal_x, goal_y)
                # 创建Twist消息，并设置线速度和角速度
                vel_msg = Twist()
                if distance >= distance_tolerance:
                    vel_msg.linear.x = linear_speed
                    vel_msg.angular.z = angular_speed * (angle - self.pose.theta)
                else:
                    vel_msg.linear.x = 0.0
                    vel_msg.angular.z = 0.0
                # 发布Twist消息
                self.velocity_publisher.publish(vel_msg)
                # 等待0.1秒
                rospy.sleep(0.1)

if __name__ == '__main__':
    try:
        x = TurtleBot()
        x.move_turtle()
    except rospy.ROSInterruptException:
        pass

上述代码中，我们定义了一个`TurtleBot`类，其中包含了小海龟的位置、速度等信息，并且实现了计算小海龟到目标位置的距离和角度差的方法，以及移动小海龟的方法。在`move_turtle`方法中，我们设置了目标位置列表，然后循环移动小海龟，每次移动到一个目标位置时，先计算出小海龟到目标位置的距离和角度差，然后根据这些信息发布一个`Twist`消息，使小海龟先转弯然后直行到目标位置。