Newsgroups: comp.robotics
Path: brunix!uunet!wupost!micro-heart-of-gold.mit.edu!news.media.mit.edu!fredm
From: fredm@media.mit.edu (Fred G Martin)
Subject: all about LEGO robots, from the horse's mouth
Message-ID: <1992Mar28.143641.19911@news.media.mit.edu>
Sender: news@news.media.mit.edu (USENET News System)
Organization: MIT Media Laboratory
References: <1992Mar27.163923.27405@bcrka451.bnr.ca> <27MAR199222434437@pearl.tufts.edu>
Date: Sat, 28 Mar 1992 14:36:41 GMT
Lines: 88

There are several projects we are working on here at the MIT Media Lab
that involve computerized/electronic LEGO bricks.  The first of them
is commercially available through the LEGO company, but unfortunately
the others aren't.

There are papers, project reports, and technical data for all of these
projects.  Contact me if you're interested.


1.  "LEGO tc logo."  Consists of a kit of LEGO Technics parts (beams,
axles, gears, motors, wheels) augmented with two sensors (light and
touch) and a computer interface.  Available for MS-DOS ISA and Apple
II series computers.  Uses a version of the Logo programming language
(supporting procedural abstraction, list data structures, recursion)
with primitives added to control the motors and receive data from the
sensors.  Motors can be controlled forward/backward and with 7 levels
of speed.  Sensors are true/false, but the light sensor comes with an
optical encoder wheel so that shaft rotation/velocity can be measured.

This system is available commercially in the United States from LEGO
Systems, Inc.  (phone:  800-243-4870).  It's also available in Canada
and Australia and possibly a few other countries (contact LEGO
headquarters in your country for more information.)

Cost: about USD$500 for the starter system, which includes enough LEGO
for 2 or 3 projects, a slot card for the computer of your choice, an
interface box capable of operating three motors and two sensors,
Logo software, and documentation.


2.  "LEGO Electronic Bricks."  This project involves the creation of
dedicated, electronic LEGO bricks that can be wired together to create
different robotic behaviors. 

The bricks are in three categories:

SENSORS--- light threshold, light difference, sound, touch, others
ACTUATORS-- motors (bidirectional control), lights, beepers
LOGIC--     AND function, OR function, NOT function, flip-flop, timer

The bricks are powered by plugging them on to special LEGO bricks that
have a pair of conductors embedded in them (for those who are
familiar, this is the new LEGO 9v power system).  Input and outputs
are digital-level signals that are wired by the user.

Simple robotic behaviors can be created with just one sensor and a
motor.  Suppose the output of a thresholding light sensor is plugged
into the directional input of a motor.  Under light, the output of the
light sensor is "true," and the motor goes forward.  In the dark, the
output of the sensor is "false," and the motor goes backward.  What
happens when you mount this assembly onto a simple car platform?  It
drives forward until it hits the edge of a shadow, and then begins
oscillating about the edge of the shadow.

More complex machines can be build up by adding more bricks!


3.  "The LEGO Programmable Brick."  This project takes the approach of
embedding the entire computer into a LEGO brick that's about as big as
a deck of cards.  The computer runs Logo and is programmed over a
serial line interface, allowing a host computer to act as the brick's
keyboard and screen.  When the serial link is detached, the brick runs
its Logo program autonomously.

The first version of the LEGO Programmable Brick was created several
years ago with an embedded 6502 chip.  We are currently working on a
new version using the 68332 (Motorola's embedded control version of
the 68000).  We plan to have a multi-tasking version of Logo running
on the new brick.


4.  "The 6.270 Robot Design Competition."  Here the approach is
similar to the Programmable Brick, only using a 6811 microprocessor
running a multi-tasking C interpreter.  The packaging is less of an
issue, since the hardware is being used by MIT students, not
elementary school kids, so we're just talking about an open-faced PC
board as the controller.

This system has capability for *lots* of analog sensors (about 20), 6
motors, and infrared communications using VCR IR decoders.  It also
uses an LCD display screen which is great for debugging.


I'm about typed out for now.  If anyone wants more info about any of
these projects, please contact me.

	- Fred Martin

