线程问题及何时停止它们

Question

import time
import threading
import qi
import balldetection
import common
import cv2
import vision_definitions
import math 

lock = threading.Lock()

ball_detected = False
ip = "10.42.0.98"
port = 9559
session = qi.Session()
session.connect("tcp://" + ip + ":" + str(port))
motion_service = session.service("ALMotion")
posture_service = session.service("ALRobotPosture")
video_service = session.service("ALVideoDevice")
speak_service = session.service("ALTextToSpeech")

def detect_ball_and_act():
    global ball_detected
    print("In detect_ball_and_act")
    videoClient = video_service.subscribeCamera("nao_opencv", 0, vision_definitions.kQVGA, vision_definitions.kBGRColorSpace, 5)
while not ball_detected:
    print("Not ball detected")
    try:
        print("In try")
        frame = common.readImage(video_service, videoClient)
        if frame is not None:
            print("in none")
            hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
            img, (ret, x, y, radius, distance) = balldetection.detect_ball(hsv)
            if ret:
                print("Ball in sight at ({}, {}) with radius {} and distance {}".format(x, y, radius, distance))
                print("Performing action...")
                speak_service.say("Ball is in sight!")
                with lock:
                    ball_detected = True
            else:
                time.sleep(1.0)
    except Exception as e:
        print("An error occurred:", e)

def keep_walking_and_looking():
    while not ball_detected:
        print("Walking and looking around...")
        walk_and_look()

 def walk_and_look():
    print("In walk_and_look")
    motion_service.moveToward(0.5, 0, 0)
    time.sleep(3.0)
    motion_service.moveToward(0, 0, 0)
    time.sleep(1.0)
    motion_service.angleInterpolationWithSpeed(["HeadYaw", "HeadPitch"],     [0.5, 1.0], 0.2)
    time.sleep(1.0)
    motion_service.angleInterpolationWithSpeed(["HeadYaw", "HeadPitch"], [-0.5, 1.0], 0.2)
    time.sleep(1.0)
    motion_service.angleInterpolationWithSpeed(["HeadYaw", "HeadPitch"], [0.0, 0.0], 0.2)

walking_thread = threading.Thread(target=keep_walking_and_looking)
ball_detection_thread = threading.Thread(target=detect_ball_and_act)

motion_service.setStiffnesses("Body", 1.0)
posture_service.goToPosture("StandInit", 1.0)

walking_thread.start()
ball_detection_thread.start()

ball_detection_thread.join()
walking_thread.join()

这段代码能实现我想要的功能，但我想知道有没有更好的处理方法。这是针对一个Nao机器人，现在他的任务是在房间里走动并寻找一个球。目前他确实在找球并在房间里走，但当他看到球后，他还在继续走，这点我想要停止。我知道这是因为线程还在运行，等他走完后才会停下来，但我希望他在看到球后能完全停下来，因为接下来的步骤是让他走到球那里。这应该像一个状态机一样运作。

实时响应线程管理状态机任务调度机器人控制

线程问题及何时停止它们

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