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From: lauren%rand-unix@vortex.UUCP
Newsgroups: net.micro
Subject: Forwarded message -- Definitive message on Robot Arm
Message-ID: <13768@sri-arpa.UUCP>
Date: Thu, 17-Nov-83 19:18:38 EST
Article-I.D.: sri-arpa.13768
Posted: Thu Nov 17 19:18:38 1983
Date-Received: Mon, 21-Nov-83 23:48:20 EST
Lines: 81

Received: From cmu-ri-rover by RAND-UNIX at Thu Nov 17 15:10:44 1983
Date: Thursday, 17 November 1983 18:14:40 EST
From: Kevin.Dowling@CMU-RI-ROVER
To: lauren@rand-unix
Subject: Armatron
Message-ID: <1983.11.17.22.30.19.Kevin.Dowling@CMU-RI-ROVER>

Lauren,
	The Armatron was marketed several years ago by TOMY
in this country mostly via mail-order and some toy stores.
It's price at that time ranged from 49.95 to $60.00

A friend bought one a couple of years ago and we took it completely
apart. I didn't buy one until Radio-Shack offered them at $31.95!

The only differences I could see were that a plastic covering inside
in the R-S version was opaque vs. the clear plastic with the original
version. (Aside from comsmetic differences like Radio Shack stickers vs
TOMY stickers)

It is ALL mechanical, and is ingenious to say the least. Only ONE
motor is used to drive all axes. Any and all axes can be driven at
any one time through the use of the 3-axis joystick. (X,Y and twist)
No speed control though. 
The motions are as follows:


	    down				arm
	    wrist				up
	     ^					^
             |					|
 elbow<---   O   ---> elbow 	shoulder  <---  o  ---> shoulder
 left (ccw)  |	   right(cw)	left (ccw)	|	right (cw)
	     up					arm
	    wrist				down

Twist: CCW Open gripper		Twist: CCW wrist ccw
       CW  Close gripper		CW wrist  cw


Very well laid out for control. After a few hours of play it becomes
very easy to manipulate the arm in 3-Space quickly and pick-up and move
objects.

Mechanics: The one motor drives a series of planetary gears along an
axis. As the joy stick is moved some of these gears are engaged cause
another series of horizontal concentric (teeth on the inside)
spur gears. These are located directly below the shoulder mount
and engage gears on the arm itself. Power travels up the arm via
shafts. At each axis going up the arm these shafts end in small gears
which engage other gears connected to shafts which continue up the arm
or power that axis directly. The gripper is spring loaded so pressure
is maintained when holding something. The little hoses on the arm
in pictures are fake.

The gearing system engages also a timer that shows "energy levels"
from 1-10 as the arm is operated you run out of "energy levels"
(slow gearing) and power is shut off when 0 "energy levels" remain.
Hokey, so I disconnected it.

The mechanics and open-loop control don't make this easy to control
but Robotics Age (Nov/Dec 1982, Vol 4 No. 6) had an article on
hooking it to a micro. The suggestions were use motors to manipulate
the joysticks or solenoid to engage the gears much as the joystick would.

It definitely fun to play with it, though I have no plans to have
it under computer control. (The CMU-Rovers are projects enough!)

There are a lot of Radio-Shacks in the Pittsburgh area and I had to call
several to find one that had it. Some of stores had 300 and sold out in
a short time! I got the last one at the store I found.

I've found that TOMY has some real talented engineers on their staff.
TOMY makes toys that walk, scuttle and hop. Some wind up, some have
batteries, some are air powered.


					kevin
					(nivek@cmu-ri-rover)

PS you can forward this if you wish to info-micro or where-ever...