Alt-BEAM Archive
Message #04671
To: beam beam@corp.sgi.com
From: Terry Newton wtnewton@nc5.infi.net
Date: Sun, 20 Jun 1999 10:35:06
Subject: [alt-beam] Re: Non-beam: a Mac AVR programmer
At 09:26 PM 6/20/99 +0000, Ben Hitchcock wrote:
>If anyone's interested in getting into AT90S1200's (A pretty cool uP with
>internal EEPROM so your robot can 'remember' where walls are when the power
>cuts out)
Good luck on that one, best I've been able to do is remember what
to do when encountering a wall with particular characteristics. The
localisation methods I've seen are too complex to fit on a small
processor. Answering the questions "where am I", "what direction am
I pointing" and "how far did I just go" are major problems unless
you majorly cheat and use beacons or something like that. I doubt
bugs make maps but only remember direction and distance vectors,
relying on hard-wired instincts to get there, but even that takes
some localisation skills. Not to discourage map-making, I'm sure
I'll try. (just a program, worst that can happen is nothing...)
>I'm starting to think that using a microprocessor doesn't have to be
>non-BEAM because it's the mindset, not the method, that makes BEAM so
>successful.
Yep. In fact, a minimalist mindset is almost a necessity to make use
of tiny processors, you can't just take existing "big-robot" methods
and translate because there is only 1K-2K to fit your program and
a miniscule 32-64 bytes of memory, plus whatever the eeprom has.
Most programmers scream when confronted with such limited resources,
but beamers are used to minimalism. If approached using a philosophy
akin to beam, then it seems like a lot! Traditional robotists usually
don't get this, they often need 32-64K or even hard-drives and OS's.
Approached from the opposite (and wrong imo) direction.
> For example, if you program the robot to use a couple of
>different 'rules' that operate in parallel (Such as the light seeking except
>when a touch sensor is triggered) instead of the traditional uP serial
>instructions (go forward, if you hit a wall then reverse, then turn, then go
>forward again).
Here's a simple "no-if" robot... in pseudocode...
loop until power runs out...
get light level in leftlight, rightlight (range 0-127)
get feeler bits in leftfeeler, rightfeeler
motorL = rightlight + 30 (photo behavior transforms)
motorR = leftlight + 30
reverseL bit = right feeler bit
reverseR bit = left feeler bit (seen this before:)
run motors using motorL, motorR and bits reverseL, reverseR
Something like this could be termed a Braitenberg Vehicle
class 2b with reversers on the feelers. For class 3a...
motorL = 150 - leftlight
motorR = 150 - rightlight
Other beam-like programming methods are possible... bicore-like
things are easy to code (two counters that reset each other)
and do all sorts of wonderfully crazy things from emulating
existing beam designs to interconnecting themselves under
evolutionary control. Processors can do almost anything beam
circuits can, but allow the experimenter to take the concepts
to the nth degree and do things that would be almost impossible
to hard-wire.
> You might even have a uP 'brain' that tells the BEAM body
>what it would like to see happen, but the BEAM body could override the uP
>when it needed to. Just an idea.
Or use a uP to process senses and deliver them to an otherwise
normal beam circuit. One nice thing about this kind of architecture
is you can take wire cutters to the brain and it continues to
function. Not that that's an important consideration, often
it is more practical to make it all-uP and save parts.
>Anyway, I just thought I'd let people know about it. I know all too well
>about the multitudes of PC software out there for electronics, and the vast
>chasm where the mac equivalents should be. Perhaps if enough of us start
>doing things like this, we might be able to start to fill that void.
Hopefully this will be a trend... Mac users shouldn't be left out.
Anyone know of Mac PIC programming software?
Terry Newton
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