Line Following

This Code is for line following using Analog Distance Sensors (ADS)

What You Will Need To Run:

• Raspberry Pi
• RoboPi
• 2 Analog Distance Sensors
• A battery to run the robot
• The Code below and Robotonomy (Found in BSMRKRS on Github)

How the sensor works:

• It is based on Reflectiveness. This means the line can't be the same material as the ground.
• The ground could be 250 and the tape on the ground could be 240.
• If you print out a picture of a line, It Will Not Work, it has to be a different material, because that is what this senses.
• THIS DOES NOT SENSE COLOR. The ground could be black, the line could be black, if they are different materials (have a different reflectiveness) then it will work!

How to mount on the robot:

• Plug an ADS into pin 0 and 1. (Remember to plug into the ADS pins on the RoboPi)
• ADS plugged into pin 0:
  • Goes on the Left side (make sure that this sensor is facing toward the back of the robot)
• ADS plugged into pin 1:
  • Goes on the Right side (make sure that this sensor is facing toward the front of the robot)

How to use the sensor:

• Open Terminal
• SSH into your robot with "ssh student@192.168.21.xxx" ("xxx" is your robots serial number)
• Type in "Engineering!1" as the password
• git clone 'robotonomy' from the BSMRKRS on Github.
• Type "cd robotonomy"
• Type "python"
• Type "import setup"
• Type "import RoboPiLib as RPL"
• Type "((500 * RPL.analogRead(0))/1024)"
• The "0" is the pin number. make sure you put it into the ADS pin 0 on the RoboPi.
• You will receive a number back from this. It is the voltage multiplied by 100.
• When you receive the number repeat this for pin number 1, after you do this change the values in the code below to match your values.
• This sensor works best 10-80cm away from the ground, but works just fine below that. (more sensitive)

The Code:

• You will have to change the values 250 and 249 depending on what your values are.

The Code: (This Code does not have the self correction yet)

#Important Importing

import RoboPiLib as RPL

import setup

import multiprocessing

import time

#Start of Commands

while 1:

#Setting A and B values from ADS

A = ((500 * RPL.analogRead(0))/1024)

B = ((500 * RPL.analogRead(1))/1024)

#Taking the True and False values recieved and giving the motor commands based on the voltage recieved from the sensor

#GOES FORWARD

if(A>=250 and B>=250): #go forward

print "IT GOES STRAIGHT!"

RPL.servoWrite(0,2000)

RPL.servoWrite(1,1000)

#GOES RIGHT

elif(A>=250 and B<=249): #turn right

print "IT TURNS RIGHT!"

RPL.servoWrite(0,0)

RPL.servoWrite(1,1000)

#GOES LEFT

elif(A<=249 and B>=250): #turn left

print "IT TURNS LEFT!"

RPL.servoWrite(0,2000)

RPL.servoWrite(1,0)

#STAYS STILL

else: #stay still

print "IT CAN STAND STILL!"

RPL.servoWrite(0,0)

RPL.servoWrite(1,0)

Theory Code: (Self Correcting Code that needs fixing)

#Important Importing

import RoboPiLib as RPL

import setup

import multiprocessing

import time

import sys, tty, termios, signal

lastSighting = ""

readloop = 0

#Creating shortcuts for the commands

def turnRight():

RPL.servoWrite(0,0)

RPL.servoWrite(1,1000)

lastSighting = "R"

readloop = 0

def turnLeft():

RPL.servoWrite(0,2000)

RPL.servoWrite(1,0)

lastSighting = "L"

readloop = 0

def goForward():

RPL.servoWrite(0,2000)

RPL.servoWrite(1,1000)

def stop():

RPL.servoWrite(0,0)

RPL.servoWrite(1,0)

def jiggle():

turnRight()

time.sleep(.5)

turnLeft()

time.sleep(.5)

#Start of Commands

while 1:

#Setting A and B values from ADS

A = ((500 * RPL.analogRead(0))/1024)

B = ((500 * RPL.analogRead(1))/1024)

#Taking the True and False values recieved and giving the motor commands based on the voltage recieved from the sensor

#FORWARD

if(A>=250 and B>=250): #go forward

print "IT GOES STRAIGHT!"

goForward()

#Self Correction every 100 commands it recieves without turning

readloop = readloop + 1

if(readloop == 100):

if(lastSighting == "R"):

print "GO BACK RIGHT!"

turnRight()

elif(lastSighting == "L"):

print "GO BACK LEFT!"

turnLeft()

else:

goForward()

if(readloop > 50):

readloop = 0

#RIGHT

elif(A>=250 and B<=249): #turn right

print "IT TURNS RIGHT!"

turnRight()

#LEFT

elif(A<=249 and B>=250): #turn left

print "IT TURNS LEFT!"

turnLeft

#STILL

else: #stay still

print "IT CAN STAND STILL!"

stop()

time.sleep(2)

jiggle()

What Needs Work:

• The "Theory Code"
• A Kill Switch that stops the command line