🚀 go-pugleaf

Here is a message I posted a couple of weeks ago to sci.virtual-worlds.  
Somebody who doesn't get that newsgroup was interested in it, so here it 
is.
--------------------

I bought a power glove, and last night I rented a Nintendo with which to
try it, ripped the glove apart, and did some in-circuit testing.

The glove system is made up of the glove itself, an L-shaped structure of
three ultrasonic recievers, perhaps half a meter on a side, that fits on
the TV, and a junction box connecting the two.  The glove has two boxes--a
knuckle box and a wrist box.  The knuckle box contains the two ultrasonic
transmitters, simple driver circuitry, connections to the finger flexion
sensors, and a piezoelectric beeper.  The writs box contains a
microprocessor with a 10 MHZ (!) crystal and a handful of support
components.  It also has quite a few conductive rubber buttons on the back.

The interface to the Nintendo is a game controller emulator.  There are
several built-in programs that can be changed at any time by pushing the
buttons on the back of the wrist box.  There is one where the joystick is
controlled by moving the hand right, left, up, or down, which is good for
X-Z games.  There is one where the joystick is controlled by moving the
hand right, left, forward, or back, which is good for X-Y games.  There
are some programs optimized for certain games.  For example, there is one
for Double Dragon.  Right, left, forward, back controls the joystick.
Thumb, index finger, and last three fingers control various motions, all
available ordinarily through combinations of presses on the controller.
Hand forward and clutch makes the character climb a ladder.  Twist of the
hand causes a head butt.

The glove also has the ability to recieve downloaded programs from a
cartridge; an example of this is Joust.  I have no details of what kinds
of programs can be downloaded.

I tried Double Dragon, Joust, and an X-Y/X-Z game (Teenage Mutant Ninja
Turtles).

The glove is operated by holding it within a sensing frustrum projected
from the structure of recievers.  Good readings can be obtained within
about 20 degrees divergence outside the structure.  I don't know how far
back you can get, as I ran out of living room first.  Most orientations of
the hand give good readings, except those where the meat of the hand is
between the transmitters and the receivers.  One can push the Center
button at any time, and the joystick emulation will occur around the
current position of the glove at the center.  I suspect the device has
quite a lot more resolution than they are putting to work.

The untrasonic transmitters are controlled by three driver transistors.  I
think that one recieves a constant square wave (an inductor smooths it
out), and the other two are used to gate the two transmitters on and off.
There are four finger flexion sensors, one each on the thumb, index
finger, middle finger, and ring finger.  They are resistive elements, and
resitance roughly doubles from full extension to full flexion.  Fully
extended resistance for my glove was 100K on three of the sensors and 50K
on one.  I have no idea if this is intentional or an artifact of the
manufacturing process, but in any event, it would be a good idea to
calibrate the glove every time it is used.  Resistance is not linearly
related to flexion; there is a threshold effect, but with delicate
movements of the fingers and a little practice, one can make quite small
adjustments to resistance.  The commons of the four sensors are connected
through diodes to a common high.  The whole mess is powered by a single 5V
negative ground supply.

I think the best idea would be to replace the entire wrist box with new
circuitry.  I am looking at Motorola's 68705S3 microcontroller.  It seems
perfect for the job.  It has four high-impedance A-D converters, serial
communications built in, an EPROM for the program, several timers, and
enough parallel I/O lines to get the job done.  It requires little
external support circuitry.  I don't think it has enough oomph to do the
trig, but it should be able to handle timing calculations fine.  Though
the three receivers are good enough for game stuff, ideally one would want
to have more to cover more orientations and positions.  Perhaps a room
with a receiver at each of the eight corners would work well.

Eric Pepke                                    INTERNET: pepke@gw.scri.fsu.edu
Supercomputer Computations Research Institute MFENET:   pepke@fsu
Florida State University                      SPAN:     scri::pepke
Tallahassee, FL 32306-4052                    BITNET:   pepke@fsu

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