Teacher notes: Solution to the challenges Pro Preview

Adjust the maximum sensor measurement to be your height

from gpiozero import DistanceSensor

sensor = DistanceSensor(echo = 6, trigger = 5, max_distance = 1.88)

print("That is all!")

Avoid obstacles - steer left when DS is less than 50cm, no steer when DS is more than 60cm

from gpiozero import DistanceSensor				# a library to simplify the code
from gpiozero import Motor					# a library to simplify the code
from gpiozero import PWMLED

from time import sleep

sensor = DistanceSensor(echo = 6, trigger = 5, max_distance = 2)

forwardPin = 27
backwardPin = 22
leftPin = 23
rightPin = 24
Motor.left = Motor.forward					# define left() function alias for easier reading later
Motor.right = Motor.backward					# define right() function alias for easier reading later

move = Motor(forwardPin, backwardPin)
steer = Motor(leftPin, rightPin)
move.stop()
steer.stop()

try:									# ignore that keyword, it is very very advanced stuff
	while True:
		# wait obstacle
		move.forward()
		while sensor.distance > 0.50:
			sleep(0.1)					# wait obstacle in front
		#eof while no obstacle
		move.stop()						# avoid collision
		print("Obstacle N%d detected" % (i+1))
		
		steer.left()
		move.forward()						# steer to avoid the obstacle
		while sensor.distance < 0.60:
			sleep(0.1)					# wait obstacle in front
		#eof while there is still an obstacle in front of us
		
		move.stop()
		steer.stop()						# path is clear, continue straight
		print("Clear path N%d detected" % (i+1))
		      
	#eof forever loop
	
except KeyboardInterrupt:						# more advanced stuff happening
	pass								# all that helps the program to continue
move.stop()
steer.stop()