Take a PicAxe brain, add an infrared "whisker" and a motor controller, transplant to an existing wall follower robot and you have:

"CRAZY Mouse Bot on Steroids!"

For the issues and tricks, here`s what I did:

* Mount the Power Transistors right down at the motors, if you bend them like wings, you can connect to their bases and feed power directly from the on/off switch
* With the batteries I`m using AA-1700 mah, you have to turn off brown out protection to allow the processor to go under 3 and 1/2 volts or so, you also need to keep the batteries fresh
* The four battery clip is a little large and collides with the top of the back, shim it in the back so it leans forward, that works.

That`s it!!

Have fun programming your MouseBot!!!

Take an innocent little twenty dollar wall follower mouse, add another twenty to motorize and electronic-ize it, and you've got a pretty fun object avoiding, wall following mouse.

I played around with the motors, though cheapo's they are pretty efficient and the maximum current drain per motor is less than 500 Ma... A one Amp Motor driver will work nicely. That means I can run the whole enchilada with a pic or even picAxe chip and something to drive the current to the wheels.

Just one mechanical "feeler" drives a switch that turns on both motors until it builds enough pressure to switch the motor off, pulling away from the wall and switching the drive motor on again.

It works. Of course it wiggles a lot.

Basically, it's most often sold as a kit of parts. It requires basic soldering skills and ability to put self tapping screws into too soft plastic while not stripping the threads.

You need a bracket for the picAxe, so I took the bare PC board and experimented with mounting it inside the mouse body. Clearance is tight in there, so I had to make sure there was enough room to allow me to mount the IR Detector, low, and in roughly in the area of the bot's nose, but set well back in the plastic.

A little sticky back tape and I get a chance to see if I have the clearance for the IR "nose" as I call it, the placement of the IR generator diodes which stick out of the eye sockets and provide illumination for the "nose," and make sure their is room for the batteries. Four AA cells.

Looks good now. Ready to move ahead.

Here's the basic circuit of the mouse's nose, er, uh, eyes... Basically the mouse's sensory input from the outside world.

I did this very scientifically, I stuffed the IR emitter diodes into the circuit boards, lined up the PC board...

Then I just guestimated using a magic marker. Drilled, and voila! Eyes looking protrusions. I put a little heat shrink sleeve on the body of each of the IR LEDs so I could keep the IR outside of the clear cover, and keep the IR detector inside the plastic body.

I did experiments... To test how to best get the nose/eyes to work.

These are the detailed shot of the LED eyes, showing how to make the heat shrink keep light outside the mouse body.

Now that the parts are soldered on the board we can stick the body into place and make sure everything fits. If it doesn't we will have an issue. Fortunately, it all fits rather nicely.

The moment of truth. Actually demonstrating MouseBot's external sensitivity. His IR "whiskers" so to speak.

Everything still looks good. So let's shoot the juice to it and see how it runs. No longer a blind mouse, we need to put some electrons into those motors. Next

Only this time we are controlling the motor's on and off time with transistor switches. Now we can drive the mouseBot in the same way as the wall follower, but it is no longer necessary to use the little bit of spring wire and a switch. Now we are using the sensory parts so we replace the mechanical arrangement with an IR beam of invisible (to humans) light.

The picAxe Basic program brings some civilizing possiblities. For example, rather than having the mouse constantly turning left, then right, then left as it moves along the way, I gave it sort of a long long short kind of deal...

Say you start a wall-follower in the middle of a room. If it is dumb, it will go around in tight circles, if not so dumb, it would simply widen the circles...

In software I go Two Motors On, Read Beam, If broken, only One motor on. So it goes in straight lines till it comes to an obstacle. As long as the IR detector indicates a wall, it will begin "wall following" but when it's out in the open on it's own, it goes on a journey more or less straight ahead, till it finds a wall.

----------------------------------------


' ------------------------------------------------------------
' BEAM bot Brains
'
' Basic Operation of mouse as "wall hugger" just like original
' Except for:
' IR detector "whiskers" lets the mouse find it's way
' Follows walls without physically touching
' Still has basic motor control with microcontroller picAxe m8
' Copyright 2008 Jim Huffman
' Permission granted to experimenters to use all or part
' Note copyrighted material frequency chart at the end


' Basic Interpreter Directives
#picaxe 08m


' Microprocessor pinouts and layouts 08m
symbol LED = 0 '(leg 7) Serout/LED
symbol rightDrv = 1 '(leg 6) High = motor on
symbol pout = 2 '(leg 5) PWMout2
symbol IRin = 3 '(leg 4) Input only pin3
symbol leftDrv = 4 '(leg 3) High = motor on
' (leg 1 Vdd, leg 8 = Vss, leg 2 = Serial In)
symbol spkr = 0 'extra symbol, speaker drive

' Variables used in program
symbol xCnt = b0
symbol rightDrvFlag = b1
symbol leftDrvFlag = b2
symbol objDetFlag = b3
symbol rightDrvTime = b4
symbol leftDrvTime = b5

init: ' Initialize chip so OK with low Vcc supply
disablebod
setfreq m4
' flash LED
high LED
pause 1000
low LED
pause 1000 'wait for Panic resets, etc...

' initialize variables
leftdrvTime = 120 ' Permits balancing forward motion
rightDrvTime = 100 ' allows motor speed balancing
low rightDrvFlag, leftDrvFlag, objDetFlag, xCnt ' initialize values


' Main driving loop avoids walls
main:

gosub driveforward
pause 10

goto main



' Move forward one time after the other - makes mouse wiggle
driveforward:
gosub objDetect 'makes 1/2 wiggle unless there is an object
' the other 1/2 wiggle even if there is a wall
high leftDrv
pause leftDrvTime
low rightDrv,leftDrv 'stop\
pause 10
return

' Driving commands (turns) stick in the appropriate spots
turnRight:
high rightDrv
pause rightDrvTime
low rightDrv,leftDrv 'stop
return

turnLeft:
high leftDrv
pause leftDrvTime
low rightDrv,leftDrv 'stop
return

' If an object is "sniffed out" then set objDetFlag high
objDetect:
pwmout pout, 22, 50 '25, 52 ' 26 usec period = 38.4 kHz
pause 3 ' Begins continuous output PWM

if pin3 = 0 then ' Object Detected
pause 3
pwmout pout, 0, 0 ' stop the continuous pulse output
else
' 1/2 wiggle (unless there's a wall)
high rightDrv
pause rightDrvTime
low rightDrv,leftDrv 'stop
pause 10
endif
pwmout pout, 0, 50 ' stop the continuous pulse output

return



MakeSound: ' fast-beep make a squeek...
setfreq m8 'kick into high-speed mode
for xCnt = 100 to 130
pulsout spkr, xCnt
next xCnt
low spkr
setfreq m4
return


' Chart of frequencies courtesy of PHAnderson...
'------------------------------------------------
' From IR_1.Bas
'
' copyright, Peter H Anderson, Baltimore, MD, May, '04

'
#rem ' PWMOut pout, Period, DutyCycles
PWMOut pout, 25, 52 ' 38.4 kHz
PWMOut pout, 24, 50 ' 40.0 kHz
PWMOut pout, 23, 48 ' 41.6 kHz
PWMOut pout, 22, 46 ' 43.5 kHz
PWMOut pout, 21, 44 ' 45.5 kHz
PWMOut pout, 20, 42 ' 47.6 kHz
PWMOut pout, 19, 40 ' 50.0 kHz
PWMOut pout, 18, 38 ' 52.6 kHz
PWMOut pout, 17, 36 ' 55.5 kHz
PWMOut pout, 16, 34 ' 58.8 kHz
#endrem