A lego maze solver

[A Johnstone <adrian@cs.rhul.ac.uk>]

Dear all,

yesterday I showed the people who came to Wayne's monthly micromouse
supper my design for a maze solver made completely from Lego. My goal is
to produce a design that can be made up by anybody with a standard Lego
Mindstorms kit. The present prototype is work in progress, but I think
something that looks very like it will work.

The design challenges include:

1. the Mindstorms RCX brick has very limited sensor capability,
2. only two motors are supplied,
3  lego is pretty floppy, and gear trains display lots of whiplash so
   everything is pretty vague from a mechanical engineering point of
   view.

My basic design has:

 a square frame with axles south and west driven by one motor,

 a pair of racks driven by a worm gear which raise and lower orthogaonal
 undriven wheels; one for the north side and one for the east,

 a rotation sensor which measures axle rotation,

 a clutch that slips if the mouse pushes against a wall: hence the
 rotation sensor both measure how far we've gone and whether we've driven
 into a wall.


The mouse can move north, south, east and west; runs reasonably true
across several squares; and can tell when it is blocked, so I think I've
got a mechanical platform that will do the job, albeit rather slowly
because it has to cuddle up to a wall to detect it. The mouse is very
robust and will not, I think, shake itself to pieces. Over the wqeekend I
hope to get started with NQC (a C-like programming language that generates
programs written in RCX byte code) and show some independent movement:
right now the mouse is controlled with an infra-red remote control.

I'll try and make some pictures and put them on a web page for your
amusement.

                           Adrian

Dr Adrian Johnstone, Senior Lecturer in Computing, Computer Science Dep,
Royal Holloway, University of London,  Egham, Surrey, TW20 0EX, England.
Email a.johnstone@rhul.ac.uk Tel:+44(0)1784 443425 Fax:+44(0)1784 439786