Tony Montana

I spent today getting the code sorted to make the robot follow a line.

The actual code was a lot longer originally but it's nice and compact now.

I'm not sure at what point a piece of code becomes your own; so far I have read through other peoples code, cherry picked the bits I like and then changed them to suit my application.  Apart from naming variables/commands etc and choice of GPIO pins there must be a finite amount of ways to control a line following robot using Python and I guess even if I think this piece of code is unique, it probably isn't.

Anyway, I have spent considerable time on it and it works so whether its truly mine or not I take pride in it.

Update: I put a line of insulation tape on the kitchen floor for the robot to follow and it didnt seem to pick it up as well as when I had the robot on the desk in my office.  The floor is more reflective in the kitchen and the robot seemed to spend a lot of time with 3 lights on and getting confused.  In addition to this I accidentally dropped a screwdriver onto some of the contacts on the line sensor; there was smoke and a smell of burning.  It still seems to work ok...

I think I am going to do another test run but without the section of code where it has an action to take if 2 sensors pick up the line.  And i'll have to do that another day as Jane has just got home and is wondering why there is a line all around the kitchen.

Here's todays code:

import RPi.GPIO as GPIO, sys, time

#use physical pin numbering

GPIO.setmode(GPIO.BOARD)

#pins:  7:left rev, 11:left for, 13:right for, 15:right rev.


GPIO.setup(7, GPIO.OUT)
GPIO.setup(11, GPIO.OUT)
GPIO.setup(13, GPIO.OUT)
GPIO.setup(15, GPIO.OUT)

def Stop():
    GPIO.output(7, GPIO.LOW)
    GPIO.output(11, GPIO.LOW)
    GPIO.output(13, GPIO.LOW)
    GPIO.output(15, GPIO.LOW)

def Forward():
    GPIO.output(7, GPIO.LOW)
    GPIO.output(11, GPIO.HIGH)
    GPIO.output(13, GPIO.HIGH)
    GPIO.output(15, GPIO.LOW)

def Reverse():
    GPIO.output(7, GPIO.HIGH)
    GPIO.output(11, GPIO.LOW)
    GPIO.output(13, GPIO.LOW)
    GPIO.output(15, GPIO.HIGH)

def Left():
    GPIO.output(7, GPIO.LOW)
    GPIO.output(11, GPIO.LOW)
    GPIO.output(13, GPIO.HIGH)
    GPIO.output(15, GPIO.LOW)

def Right():
    GPIO.output(7, GPIO.LOW)
    GPIO.output(11, GPIO.HIGH)
    GPIO.output(13, GPIO.LOW)
    GPIO.output(15, GPIO.LOW)

def Hardleft():
    GPIO.output(7, GPIO.HIGH)
    GPIO.output(11, GPIO.LOW)
    GPIO.output(13, GPIO.HIGH)
    GPIO.output(15, GPIO.LOW)

def Hardright():
    GPIO.output(7, GPIO.LOW)
    GPIO.output(11, GPIO.HIGH)
    GPIO.output(13, GPIO.LOW)
    GPIO.output(15, GPIO.HIGH)

#speed is 0.2 m/s
#1 second hardleft or hardright = 45 degrees
#left/right is slight change in direction

#line follower
#IRleft = 16
#IRcentre = 18
#IRright = 22
GPIO.setup(16, GPIO.IN)
GPIO.setup(18, GPIO.IN)
GPIO.setup(22, GPIO.IN)



try:
    Stop()
    raw_input("Say hello to my little friend.")
    while True:
     
        lineleft = GPIO.input(16)
        lineright = GPIO.input(22)
        linecentre = GPIO.input(18)
     
#if it picks up a line the input is 0
     
        if linecentre == 0:
            if lineleft == 0:
                Left()
            elif lineright == 0:
                Right()
            else:
                Forward()

        else:
            if lineleft == 0:
                    Hardleft()
            elif lineright == 0:
                    Hardright()
            else: Stop()
 
 

except KeyboardInterrupt:
    Stop()
    GPIO.cleanup()