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4Tronix Bit:Bot Neuron Controlled Edge follower

In the last post I was playing with 4Tronix's Bit:Bot. In this post I will show the initial experimentation with an artificial neuron controlling the Bit:Bot to follow the edge of a line (it follows the left-hand side of the line).



The neurons (well two separate ones, S1 and S2) are produced using weighted sums - summing the weights x inputs [ right-hand sensor (rs) and left-hand sensor (ls)] plus a bias for each neuron in this case w[0] and w[3].
    




              


    net=w[0]+w[1]*rs+w[2]*ls      
    net2=w[3]+w[4]*rs+w[5]*ls


  If weighted sum >=0 then its output 1 otherwise 0
    if net>=0: 
        s1=1
    else:
        s1=0

    if net2>=0:
        s2=1
    else:
        s2=0

What actual causes S1 to be either 1 or 0 is all defined by a set of weights w (three for the first neurone, S1,  three for S2).

w=[0,-1,1,-1,1,-1]



Converting the outputs of the two neurones S1 and S2 into actions is shown below.
    if s1==1 and s2==1:
        forward(40)   
    elif s1==0 and s2==1:
        forward(30)
        right_turn(10)
    elif s1==1 and s2==0:
        forward(30)
        left_turn(10)       
    elif s1==0 and s2==0:
        backward(40)

The functions for forward, right_turn, etc are defined elsewhere.


At the moment the movement is a bit rough and it is a little simpler to build a version that follows the centre of the line; this approach though, works with thinner lines. 

To change the function of the system, change the values in w; for example to produce one that follows the centre of the line just change w (I will leave that to someone to work on). The complete code is shown below.


Code
from microbit import *
import neopixel, random, array

w=[]  

def forward(n):
    pin0.write_analog(551)
    pin8.write_digital(0) 
    pin1.write_analog(551)
    pin12.write_digital(0)
    sleep(n)
    
def backward(n):
    pin0.write_analog(551)
    pin8.write_digital(1) 
    pin1.write_analog(551)
    pin12.write_digital(1)
    sleep(n)
    
def right_turn(n):
    pin0.write_analog(511)
    pin8.write_digital(0) 
    pin1.write_analog(511)
    pin12.write_digital(1)
    sleep(n)
    
def left_turn(n):
    pin0.write_analog(551)
    pin8.write_digital(1) 
    pin1.write_analog(551)
    pin12.write_digital(0)
    sleep(n)
       
w=[0,-1,1,-1,1,-1]

while True:
    ls= pin11.read_digital()
    rs= pin5.read_digital()
    
    net=w[0]+w[1]*rs+w[2]*ls
    net2=w[3]+w[4]*rs+w[5]*ls

    if net>=0:
        s1=1
    else:
        s1=0

    if net2>=0:
        s2=1
    else:
        s2=0
   
    if s1==1 and s2==1:
        forward(40)   
    elif s1==0 and s2==1:
        forward(30)
        right_turn(10)
    elif s1==1 and s2==0:
        forward(30)
        left_turn(10)       
    elif s1==0 and s2==0:
        backward(40)
       
           
    


All opinions in this blog are the Author's and should not in any way be seen as reflecting the views of any organisation the Author has any association with. Twitter @scottturneruon

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