尝试让一个turtlebot在ROS中绕着另一个移动的turtlebot画圆。

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英文:

Trying to make a turtlebot circle another moving turtlebot in ROS

问题

我试图让一个名为turtle2的小乌龟围绕一个静止的小乌龟turtle1画圈,然后让另一个小乌龟turtle3围绕turtle2画圈。Turtle2围绕turtle1画圈,半径为2,角速度为1,而turtle3应该围绕turtle2画圈,半径为0.5,角速度为2。然而,我无法想出如何使turtle3围绕turtle2画圈,同时又缩短了由turtle2运动造成的距离。这是我的ROS代码和我的结果的屏幕截图,以帮助您理解我的目标。任何帮助将不胜感激。

英文:

I am trying to make one turtlebot named turtle2 to circle around a stationary turtlebot and then have another turtlebot turtle3 circle around turtle 2. Turtle2 circles around turtle1 with a radius of 2 and an angular velocity of 1 and turtle3 should circle around turtle2 with a radius of 0.5 and an angular velocity of 2. However I cannot figure out how to make turtle3 circle around turtle2 while also closing the distance caused by turtle2's movement. Here's my ROS code and a screenshot of what I get with my results to help you understand my goal. Any help would be appreciated.

#!/usr/bin/env python  
import roslib
roslib.load_manifest('learning_tf')
import rospy
import math
import tf
import geometry_msgs.msg
import turtlesim.srv

if __name__ == '__main__':
    rospy.init_node('turtle_tf_listener')

    listener = tf.TransformListener()

    rospy.wait_for_service('spawn')
    spawner = rospy.ServiceProxy('spawn', turtlesim.srv.Spawn)

    # wait for the world to spawn
    rospy.sleep(0.3)

    (trans, rot) = listener.lookupTransform('/world', '/turtle1', rospy.Time(0))
    r2 = 2
    w2 = 1
    # spawn second turtle along the orbit of the first still turtle
    spawner(trans[0], trans[1] - r2, 0, 'turtle2')
    turtle_vel2 = rospy.Publisher('turtle2/cmd_vel', geometry_msgs.msg.Twist,queue_size=1)

    # wait for second turtle to spawn
    rospy.sleep(0.3)
    (trans, rot) = listener.lookupTransform('/world', '/turtle2', rospy.Time(0))
    r3 = 0.5
    w3 = 2
    # spawn third turtle along the orbit of the second turtle
    spawner(trans[0], trans[1] - r3, 0, 'turtle3')
    turtle_vel3 = rospy.Publisher('turtle3/cmd_vel', geometry_msgs.msg.Twist,queue_size=1)

    rate = rospy.Rate(10.0)
    while not rospy.is_shutdown():
        flag2 = True
        flag3 = True
        try:
            (trans, rot) = listener.lookupTransform('/world', '/turtle1', rospy.Time(0))
        except (tf.LookupException, tf.ConnectivityException, tf.ExtrapolationException):
            flag2 = False

        if(flag2):
            angular2 = w2
            linear2 = w2 * r2
            cmd2 = geometry_msgs.msg.Twist()
            cmd2.linear.x = linear2
            cmd2.angular.z = angular2
            turtle_vel2.publish(cmd2)
        
        try:
            (trans, rot) = listener.lookupTransform('/turtle3', '/turtle2', rospy.Time(0))
        except (tf.LookupException, tf.ConnectivityException, tf.ExtrapolationException):
            flag3 = False

        if(flag3):
            angular3 = w3
            linear3 = w3 * r3
            cmd3 = geometry_msgs.msg.Twist()
            cmd3.linear.x = linear3
            cmd3.angular.z = angular3
            turtle_vel3.publish(cmd3)

        rate.sleep()

尝试让一个turtlebot在ROS中绕着另一个移动的turtlebot画圆。

答案1

得分: 0

这是我处理的方式:

  1. 获取turtle2的位置,我们称其为Pos2,它是一个向量(x2,y2)。
  2. 创建一个生成围绕(0, 0)旋转的点的函数,类似于SpinnerPos =(cx,cy)= DistanceToCenter *(cos(angle),sin(angle)),其中angle每帧增加,因此该点(也称为向量)会旋转。
  3. 将它们组合起来:Target = Pos2 + SpinnerPos。现在,如果绘制目标点,它将完美地围绕turtle2旋转。
  4. 现在,通过计算到目标点的距离(勾股定理)并根据距离调整其方向(三角函数atan2())和速度,使turtle3跟随目标点。
  5. 调整参数后,turtle3应该围绕turtle2旋转。
英文:

That's how I would approach it:

  1. Get turtle2 position let's call it Pos2 which is vector (x2, y2)
  2. Make a function which generates point which is circling around (0, 0) so it's something like SpinnerPos = (cx, cy) = DistanceToCenter * (cos(angle), sin(angle)) where angle is incremented every frame so the point (aka vector) would spin.
    尝试让一个turtlebot在ROS中绕着另一个移动的turtlebot画圆。
  3. Combine both: Target = Pos2 + SpinnerPos. Now if drawn Target point would perfectly spin around turtle2
  4. Now make turtle3 follow Target point by calculating distance to it (Pythagorean theorem) and adjusting it's orientation (trigonometry atan2()) and speed proportional to distance
  5. After tuning parameters turtle3 should circle turtle2

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  • 本文由 发表于 2023年5月28日 19:34:35
  • 转载请务必保留本文链接:https://go.coder-hub.com/76351277.html
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