Convert an old broken down Rumble Bot into a wandering autonomous robot.

It`s cheap and really easy to make an old Rumble Bot into a new, more self oriented obstacle avoiding Robot.

Rumble Bot = 5 - 30 bucks (broken ones are fine, you are going to "gut" the electronics anyway.

picAxe Motor Control PC board (comes with picAxe 08 chip) < $16 bucks

picAxe 08m chip (less than 4 bucks)

IR "Eyes": around $12 dollars, works in every light level, impervious to false triggers.

A 0.22 uf capacitor on the output of the above to keep it from jittering the interrupt pin...

My total cost = $35 USD... It`s an easy way (programmed in BASIC) and cheap way to learn about autonomous robots.

The Rumble Bots are getting harder to find since the big push to put an arduino inside.

You can make just about any four wheel drive (or even 2wd with dragger wheel) into an autonomous robot.

You could use mechanical "feelers," but it`s more exciting and a little more money to use an IR range finder system to let you know when objects are in the way. With a decent `avoid` algorithm, you`ll have instructions left over.

The simplest program allowing the unit to operate as shown in the video can be expanded to include other items. But with the simple picAxe motor driver board, everything is pretty simple to start with.

I took everything out of my Rumble Bot and rewired the motor and speaker, etc... This looked like the bot was getting a hair cut, but made things work smoothly and nicely.

Some plastic will have to be removed to make it all work. I had to use a Dremel tool, to get the head of the robot to fit nicely. Moving the extra plastic out to mount the driver board was simply clipping with a pair of sharp cutters.

Now you mount the IR detector on the body. Just on the outermost edge of the body. This allows you to adjust the height by adding shims as needed before tightening the mounting screws.

If you don`t, you`ll find your robot rejecting the edges of a carpet or other simply climbed object. The beam should not be too low, nor too high, as it will run into objects and get caught if the beam is too high to recognize items.

`-------------------------------------------------------
`
` picAxe Motor Control
` Created by: Jim Huffman
` Rev 0.1 October 18, 2007
` Rev 0.2 October 20, 2007 JH
` Rev 0.3 look around functions begun Oct22, 2007
` Rev 0.4 Changed Motor Drive approach Nov 04, 2007
`
`-------------------------------------------------------
`
` Initialize System Wide Values
`
` Directives
` Select and initialize chipset
#picaxe 08m
`
` System resources
symbol fwdM1 = 0 `(pin 7)(Careful, Used in Programming)
symbol revM1 = 1 `(pin 6)
symbol revM2 = 2 `(pin 5)
symbol IRsense = 3 `(pin 4)(input only on 8 pin)
symbol fwdM2 = 4 `(pin 3)
` (pin 1 Vdd, pin 8 = Vss, pin 2 = Serial In)
`
` Motor Control constants
` assumptions:
` open means no output
` motors are M1 and M2
` powered by 4x 1.2v AA cells built-in robot
` vars
symbol storResult = w2 ` place to put ADC10 results
symbol storResShrt= b4 ` place to put adc results
`
`
`--------------------------------------------------------
` Code Blocks:
`
let dirs = %00010111
` short wait before main routine begins
setint %00001000, %00001000
`
` main demo routine

`It goes like this
` gosub (fwd,rev,leftspin,rightspin)
` pause - long as you want it to do the appropriate subroutine
` gosub stopAll - You have to stop it from driving, don`t forget this
` That`s how you make the world go round
`
init: `gosub fwd `basically, you make it go, then you pause for running time
`obviously, an interrupt loop makes it quit driving anytime
gosub stopAll `don`t forget to stop the action you put in motion
pause 3000 `think and abandon all hope loop

main: gosub fwd
pause 50
goto main


interrupt:
`if pin3=1 then interrupt
gosub stopAll
pause 20 `think a second little machine :-)
gosub iSpy
setint %00001000, %00001000
return


` Look to see if a spot is clear, then head in that direction
iSpy:
gosub rev
pause 600
gosub stopAll
gosub leftSpin
pause 700
gosub stopAll
if pin3 = 1 then `still in trouble that way
gosub leftSpin ` call yourself until you`re out of trouble
pause 300
gosub stopAll
pause 100
if pin3 = 1 then `still in trouble that way
gosub rev
pause 300
gosub stopAll
gosub rightSpin ` call yourself until you`re out of trouble
pause 400
gosub stopAll
pause 100
return
endif
endif

return ` found a hole - start driving again


`-----------------------------------
` Drive Routines
`
fwd:
high fwdM1, fwdM2
pause 30
return

rev:
high revM1, revM2
pause 30
return

stopAll:
low fwdM1, fwdM2, revM1, revM2
pause 30
return

leftSpin:
high fwdM1
high revM2
pause 30
return

rightSpin:
high revM1
high fwdM2
pause 30
return

You can do some pretty fun things. Like actually move the whole robot back and forth till it finds an obstacle free direction to go. Or it runs up on things it sees, using ADC to measure the actual distance and then look around for something else to run up to.

Speed control is also possible, you can PWM out on 8 bit chips, thus you can allow the robot to go kinda slow while it looks around, then speed up when it is out in the open.

Much fun can be had with the simple bot as-is, but you can do more, like put sensors in the bots fists so it can detect objects it runs into despite the IR Detector. Also, there is a speaker you can bleep out tunes and you can put a rear bumper to discover objects when backing up.

A cheap-o like me simply finds this much fun for such a small price too much hobby robot fun!!!