使用 python ev3 进行多线程处理，join 方法不起作用

如何解决使用 python ev3 进行多线程处理，join 方法不起作用

我正在运行代码，一切正常，但 join 方法不起作用。

我必须等待所有线程完成旋转 90 度

我尝试使用不同代码的 join 方法，并且与 ev3 机器人无关，但我不明白为什么它不能与 ev3 一起使用。

错误: AttributeError: 'Thread' 对象没有属性 'join'

#!/usr/bin/env pybricks-micropython
from pybricks.hubs import EV3Brick
from pybricks.ev3devices import (Motor,TouchSensor,ColorSensor,InfraredSensor,UltrasonicSensor,GyroSensor)
from pybricks.parameters import Port,Stop,Direction,Button,Color
from pybricks.tools import wait,StopWatch,DataLog
from pybricks.robotics import DriveBase
from pybricks.media.ev3dev import SoundFile,ImageFile
import threading

# This program requires LEGO EV3 MicroPython v2.0 or higher.
# Click "Open user guide" on the EV3 extension tab for more information.


# Create your objects here.
ev3 = EV3Brick()


left_motor = Motor(Port.B)
right_motor = Motor(Port.C)


robot = DriveBase(left_motor,right_motor,wheel_diameter=55.5,axle_track=104)

obstacle_sensor  = UltrasonicSensor(Port.S4)

obstacle_sensor_gyro = GyroSensor(Port.S3)
################################

def check_for_75_angle():
    while True:
        angle = obstacle_sensor_gyro.angle()
        print(angle)
        if angle > 75:
            robot.drive(0,15)
            break
            


def check_for_90_angle():
    while True:
        angle = obstacle_sensor_gyro.angle()
        if angle == 90:
            break
            

def turn():
    robot.drive(0,80)
    


def main():
    t1 = threading.Thread(target=check_for_75_angle)
    t2 = threading.Thread(target=check_for_90_angle)
    t3 = threading.Thread(target=turn)

    t1.start()
    t2.start()
    t3.start()

    t1.join()
    t2.join()
    t3.join()




while True:
    cm = obstacle_sensor.distance() * 0.1

    if cm < 20:
        obstacle_sensor_gyro.reset_angle(0)

        main()
        print("Finished: 90 angle")

    else:
        robot.drive(20,0)
    ```