How to move my ev3 robot a certain distance and get it to stop?

Question

I'm starting out with an EV3 lego robot and my first project to pop the cherry was getting it to move a certain distance, and having it stop when the ultrasonic sensor dectects something 3 cm away. But I have tried so many things and can't get it to work right. here is my code:

#!/usr/bin/env python3
from ev3dev2.motor import MoveTank, OUTPUT_B, OUTPUT_C, seconds
from ev3dev2.sensor.lego import TouchSensor
from ev3dev2.sensor.lego import UltrasonicSensor
from time import sleep
from time import seconds


us = UltrasonicSensor()
tank_pair = MoveTank(OUTPUT_B, OUTPUT_C, seconds)


tank_pair.on(left_speed=30, right_speed=30)

if distance_centimeters(10):  
    tank_pair.off()

Any help would be appreciated.

Answer 1

I believe you need something like this:

import time
...
while us.distance_centimeters() > 10.0:
    time.sleep( 0.1 )
  
tank_pair.off()