Message-ID: <12164@sri-arpa.UUCP>
Date: Wed, 19-Sep-84 06:24:21 EDT
Article-I.D.: sri-arpa.12164
Posted: Wed Sep 19 06:24:21 1984
Date-Received: Wed, 26-Sep-84 01:03:16 EDT
Lines: 51

From:  Lauren Weinstein 

Sometime ago, I brought up the subject of the Radio Shack (Robatron/Armatron)
robot arm as a possible cheapo robotic arm for experimentation.  The unit
was fairly cheap (around $30-$40) at least in comparison to existing
alternatives.  While some experimenters have successfully interfaced the
unit to computers in very elaborate fashions, it is a tough task due to
the mechanical nature (only one actual motor) of the arm linkages.

I eventually decided not to buy the unit.

Now, a new toy has appeared, which I have already bought and with which
I am very pleased.  The unit I bought is the "Robotix 2000" from
Milton Bradley.  It costs around $48 at typical discount.  This immensely
clever robotic building toy goes far, far beyond the capabilities of the
Radio Shack arm at a similar price.  The basic unit consists of a wide
variety of plastic parts (levers, extension arms, bases, elbows, etc.),
4 battery powered electric motors (internal gearing, very high torque),
and all sorts of other parts.  They easily fit together through a very
clever "octagon" arrangement that seems unlikely to wear out easily.
There is also a somewhat cheaper unit (the "Robotix 1000") with only
2 motors and fewer of other parts as well.

The unit I bought can be assembled in an infinite number of ways -- 
in 15 minutes I built a robot hand (padded pinchers are included) that
used all four motors, had high flexibility, and something like a three
inch grip.  Motors can also be used for propelling the entire unit
for rolling or walking.  A lot can be done with the four motors, and
by December additional motors will be available for about $14/pair,
as well as other parts packages.  Some simple experiments to test the
lifting power of the unit, and the ability of the plastic pieces to
take heavily out-of-balance weights, was quite surprising.  While I had
no convenient way to measure the weights I was using, I was impressed
with how much weight could be lifted without stalling the motors.  In
fact, I was unable to stall the motors with any weight easily at 
hand which could be conveniently gripped.  (I was able to lift weights
that would fall back down when power was removed, but that's to 
be expected with weights beyond a certain point.)

Perhaps most importantly, since the motors are all individually
controllable, the unit should be exceedingly trivial to interface
to computers, and also appears to be ideally designed for the
addition of feedback sensors of various types.

Given that most robotics equipment for experimenters costs many
hundreds of dollars at a minimum, this unit seems like a good
buy for the casual experimenter.

Oh yes, it's *lots* of fun, too!

--Lauren--

Message-ID: <441@wdl1.UUCP>
Date: Wed, 26-Sep-84 21:23:38 EDT
Article-I.D.: wdl1.441
Posted: Wed Sep 26 21:23:38 1984
Date-Received: Thu, 4-Oct-84 03:51:21 EDT
Lines: 3
Nf-ID: #R:sri-arpa:-1216400:wdl1:1400008:000:123
Nf-From: wdl1!jbn    Sep 26 17:52:00 1984


    Another breakthrough from Milton Bradley, makers of the Milton Bradley
Big Trak, a programmable mobile tracked toy.