修复nxt python中的turn方法

当我的机器人遇到障碍物时，我希望能够阻止它移动。但是，

motor.py

下的

SynchronizedMotors

类中的turn方法不允许我这样做。我怎样才能解决这个问题？有没有直接的解决办法？我确实尝试过使用线程，但没有成功。

让伺服系统对传感器输入做出反应没有问题。以下操作应使机器人以最大功率前进，直到按下一个或多个触摸传感器，然后停止，等待片刻，然后切断伺服系统的所有电源

from time import sleep
import nxt

from nxt.motor import Motor, PORT_B, PORT_C
from nxt.sensor import Touch, PORT_1, PORT_2

class Robot(object):

    def __init__(self, brick):

        self.brick = brick

        # left and right motors
        self.lmotor = Motor(brick, PORT_B)
        self.rmotor = Motor(brick, PORT_C)

        # left and right touch sensors
        self.ltouch = Touch(brick, PORT_1)
        self.rtouch = Touch(brick, PORT_2)

    def roll(self, left, right):
        '''
        Non-blocking function for modifying power to servos.
        The servos will continue to operate at these power
        levels until told to do otherwise. Values are given
        as percentages of full power, so torque will change
        as the battery loses charge. A negative value will
        reverse the rotation of the respective servo.
        For example, to spin on the spot, clockwise and at
        full power, do

            self.roll(100, -100)

        '''
        self.lmotor.run(left)
        self.rmotor.run(right)

    def halt(self):
        '''
        Stops and then holds both servos steady for
        0.2 seconds, then cuts power to both servos.
        '''
        self.lmotor.brake()
        self.rmotor.brake() 
        sleep(0.2)
        self.lmotor.idle()
        self.rmotor.idle()


brick = nxt.find_one_brick(name='R2')
robot = Robot(brick)

robot.roll(100, 100)
while True:
    if robot.ltouch.is_pressed() or robot.rtouch.is_pressed():
        robot.halt()