Robo trolley Functions | Python Fiddle

#!/usr/bin/env python
import time,RPi.GPIO as gpio
import RPi.GPIO as GPIO

def setup():
    gpio.setwarnings(False)
    gpio.setmode(gpio.BOARD)
    gpio.setup(19, gpio.OUT)
    gpio.setup(21, gpio.OUT)
    gpio.setup(24, gpio.OUT)
    gpio.setup(26, gpio.OUT)

def offmotors():
    gpio.output(26,0)
    gpio.output(24,0)
    gpio.output(21,0)
    gpio.output(19,0)
    print("motors off")

def forward():
    print("moving forward")
    gpio.output(26,0)
    gpio.output(24,1)
    gpio.output(21,0)
    gpio.output(19,1)

def backward():
    print("moving backward")
    gpio.output(26,1)
    gpio.output(24,0)
    gpio.output(21,1)
    gpio.output(19,0)

def Sensor_Input_to_Distance(Sensor):
    # Use BCM GPIO references
    # instead of physical pin numbers
    GPIO.setmode(GPIO.BCM)

# Define GPIO to use on Pi
    if Sensor == FRONT:
        GPIO_TRIGGER = 23
        GPIO_ECHO = 24    
    else
        GPIO_TRIGGER = 23
        GPIO_ECHO = 24

print "Ultrasonic Measurement"

# Set pins as output and input
    GPIO.setup(GPIO_TRIGGER,GPIO.OUT)  # Trigger
    GPIO.setup(GPIO_ECHO,GPIO.IN)      # Echo

# Set trigger to False (Low)
    GPIO.output(GPIO_TRIGGER, False)

# Allow module to settle
    time.sleep(0.5)

# Send 10us pulse to trigger
    GPIO.output(GPIO_TRIGGER, True)
    time.sleep(0.00001)
    GPIO.output(GPIO_TRIGGER, False)
    start = time.time()
    while GPIO.input(GPIO_ECHO)==0:
        start = time.time()

while GPIO.input(GPIO_ECHO)==1:
        stop = time.time()

# Calculate pulse length
    elapsed = stop-start

# Distance pulse travelled in that time is time
    # multiplied by the speed of sound (cm/s)
    distance = elapsed * 34000

# That was the distance there and back so halve the value
    distance = distance / 2

print ( "Distance : %.1f" % distance )

# Reset GPIO settings
    GPIO
           
    return distance

def Wifi_Owner_Near (WIFI_SSID):
    """
    use library funciton from raspberry PI to get signal strength
    handle dynamic signal level for
    Dummy signal strength
    """
    #dummynear = prompt("Dummy Near or not? (Yes or No)")
    
    #if near = True
    near = True
    #else:
       # near = False     
        
    return

def Create_Motor_drive_instructions (Movement):

#Make robot move
    return False

def Drive_Robotrolley(distance):
 
    if distance > (MINDIST + BUFFER) <MAXDIST:
        Forward () # turn motor on
        while 
             distance = getdistance()
             distance > MINDIST
                
       
        
    else:
        
        
    
 
    
    #Variable definition
Movement = 0 #integer dictating if move forwards - 1, stop -0, or move backwards -1
FRONT = 0 #integer for front sensor selection
REAR  = 1 #integer for rear sensor
WIFI_SSID = "" #String to hold SSID
distance = 0 #integer for number of centimeters from nearest object in front of ultrasonic sensor
near = False #bool for whether wifi is near or not
MINDIST = 50 
MAXDIST = 200
FORWARD = 1
BACKWARD = -1 
STOP = 0
BUFFER =5

# Main function to decide how the trolley moves
def TrolleyControl():
    #if Owner near trolley then we can consider moving
    if Wifi_Owner_Near (WIFI_SSID):
	    # Use ultrasonic sensor to check if the trolley is close to owner
        
        Movement = Stop_Forward_or_Backwards(Sensor_Input_to_Distance(FRONT))
        
        # -1 returned int movmement, move backwards, 0 returned, stop, 1 returned move forward
        Create_Motor_drive_instructions (Movement)
    else:
        #Owner is not close to trolley
        #display a message or sound a beep
        Movement = 0
    return

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