Roboty

Featured on the cover of the Feb 1997 issue of Dr. Dobbs Journal

Last updated 12 November 1998

This page is always growing, please e-mail me if you have any suggestions and/or useful links.

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Roboty as of early August 1996 with the prototype sensor head turned to look into the camera. (Note 1 foot ruler in foreground for scale).

Some time ago I started a project to build a six-legged autonomous robot. The legs are controlled by a pair of RC aircraft servo-motors for each leg. Each servo-motor pair is controlled by a Motorola MC68HC705K1 processor. This CPU has 504 bytes of OTPROM, 32 bytes of RAM and 64 bits of EPROM, it has 10 I/O lines and fits in a 16 pin DIP. I programmed the processor to have two PWMs to control the motors, and to communicate with a supervisory CPU (originally over a nibble wide "bus", but now using SPI). All six controllers are daisy-chained together on the bus and have jumper settable bus addresses. The MC68HC705J1 is a similar, slightly larger controller.

The robot is built on a frame made of U-channel aluminum, and has 1/4" aluminum rods for the main part of the legs.

I have learned a lot about six-legged gaits (which turn out to be an un-natural motion for bipedal humans -- the book by Song and Waldron was a great help).

The thing seems to have started a life of its own:

My cat likes it; I think she thinks the humming motors means that it is purring.
My five year old son loves to run it from the PC interface. He even named it: roboty
It has its own Web page!

How do the different kinds of batteries perform ?

I stumbled across this interesting demonstration, by Noel Rode (noel@dgs.monash.edu.au), of how the MIT robot Genghis walks (zipped binaries for DEC, SUN, SGI, Linux and DOS, 393Kb).

Another view of Roboty next to ROCI

The current status of Roboty

A newspaper article on Roboty from the Monterey Herald (26 August 1996).

I am building this machine from scratch using an Emco Unimat-3 mini-lathe/mill for the metal and plastic parts. If you are mechanically inclined you might want to take a look at the Personal CNC's home page

You should definitely also know about:

Small Parts Inc.
13980 N.W. 58th Court, P.O. Box 4650
Miami Lakes, FL 33014-0650
Voice: (800) 220-4242
Fax: (800) 423-9009

They are a great resource for mechanical parts, metal and plastic stock, etc. (I bought several parts that I use in roboty there, including the ball-joint "ankles" and teflon rods for bushings).

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Robotics Literature

Here is a book that I have found to be VERY useful:

Song, S-M, and K.J. Waldron, 1989; Machines That Walk: The Adaptive Suspension Vehicle, MIT Press, Cambridge Mass, 314 pages, ISBN 0-262-19274-8

And if merely walking isn't challenging enough for you:

Raibert, M.H., 1986; Legged Robots That Balance, MIT Press, Cambridge Mass, 233 pages, ISBN 0-262-18117-7

And of course there is the modern classic (not much on walking robots, but generally useful),
Jones, J.L. and A.M. Flynn, 1993; Mobile Robots, Inspiration to Implementation, A K Peters, Wellesley Mass, 349 pages, ISBN 1-56881-011-3

I see lots of questions on the net about how to control devices from the PC parallel or serial port. Here is a free copy of an excellant book by Tim Hendtlass on Real Time Forth that has this info and more. (This is a zipped Postscript file, not HTML, 1012K).
You might also want to look at my recent Forth Dimensions article.