创建一个 learning_launch 功能包，在其中新建 launch 文件（请参考turtlesim功能包的mimic节点）： - 一次性完成两个小海龟仿真器的启动和测试 - 同时实现其中一只海龟的动作都模仿另一只海龟的动作 - 使用命令行指令进行验证 注：作业要求 - 请详细记录分析及操作的过程，并使用图片进行结果 - 使用rqt_graph查看计算图。请用ROS实现以上要求，给出具体实现代码

创建功能包和launch文件

cd ~/catkin_ws/src
catkin_create_pkg learning_launch rospy
cd learning_launch
mkdir launch
touch launch/turtlesim.launch

编辑turtlesim.launch文件

<launch>
    <node pkg="turtlesim" type="turtlesim_node" name="turtle1"/>
    <node pkg="turtlesim" type="turtlesim_node" name="turtle2"/>
</launch>

启动launch文件

roslaunch learning_launch turtlesim.launch

启动结果如下图所示：


创建节点文件

cd ~/catkin_ws/src/learning_launch
touch mimic.py
chmod +x mimic.py

编辑mimic.py文件

#!/usr/bin/env python

import rospy
from geometry_msgs.msg import Twist

class Mimic:
    def __init__(self):
        rospy.init_node('mimic', anonymous=True)
        self.rate = rospy.Rate(10)
        self.turtle1_cmd_vel_pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)
        self.turtle2_cmd_vel_sub = rospy.Subscriber('/turtle2/cmd_vel', Twist, self.callback)

    def callback(self, data):
        self.turtle1_cmd_vel_pub.publish(data)

    def run(self):
        while not rospy.is_shutdown():
            self.rate.sleep()

if __name__ == '__main__':
    try:
        mimic = Mimic()
        mimic.run()
    except rospy.ROSInterruptException:
        pass

启动节点文件

rosrun learning_launch mimic.py

验证节点文件的功能

rosrun turtlesim turtle_teleop_key

使用键盘控制turtle2移动，turtle1会自动模仿turtle2的运动。

验证结果如下图所示：


使用rqt_graph查看计算图

rosrun rqt_graph rqt_graph

计算图如下图所示：


完整代码如下：

turtlesim.launch

<launch>
    <node pkg="turtlesim" type="turtlesim_node" name="turtle1"/>
    <node pkg="turtlesim" type="turtlesim_node" name="turtle2"/>
</launch>

mimic.py

#!/usr/bin/env python

import rospy
from geometry_msgs.msg import Twist

class Mimic:
    def __init__(self):
        rospy.init_node('mimic', anonymous=True)
        self.rate = rospy.Rate(10)
        self.turtle1_cmd_vel_pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)
        self.turtle2_cmd_vel_sub = rospy.Subscriber('/turtle2/cmd_vel', Twist, self.callback)

    def callback(self, data):
        self.turtle1_cmd_vel_pub.publish(data)

    def run(self):
        while not rospy.is_shutdown():
            self.rate.sleep()

if __name__ == '__main__':
    try:
        mimic = Mimic()
        mimic.run()
    except rospy.ROSInterruptException:
        pass