SHADOW Robot Project
Mark Worsdall
Hi there, I am part of the Shadow Robot project, in the UK.
We are developing a biped walker (Long term, slow going) and
another system called Liberater, both using custom built air
muscles, which have immense power, long life and are cheap!
As a side line we sell educational versions in a kit form.
The kit comprises of 12 Muscles in total, 8 Sensors, Valve
board and a serial controller board to interface with a
computer. This allows you to build a robot to your own
configuration and then program it. When you have had enough
you can take it to bits or purchase more muscles, allowing
you to keep the robot you built and then you build another.
Each muscle costs 8 pounds. The entire kit mentioned above
costs 300 pound plus 50 pound for the software.
The software is available for Archimedes (Windows), PC/IBM
(Windows) and BBC/Master (Command Line). Soon to be released
are the AMIGA (Command Line), Archimedes (Command Line)
PC/IBM (Command line) versions.
The Windows based versions for the PC and Archimedes allow
you to program the robot that you built, movements by a
graphical style language. So to fill a specific muscle
you click and grag the fill Icon, then drag it to the
section of the program where the fill operation is to occur.
All operations are done in this style.
For more details you can E-Mail me or ring the following
number, asking for Richard Greenhill.
UK (0171-700-2487)
Alternatively please SNIP article and add comments!
Paul M Atkinson
Keith Levkoff
>Are 'air muscles' the same as air cylinders (produced by Bimba, etc)? Are any details available on the valves used? I presume that position of a robot arm (for example) will vary with applied load (ie air is compressible). Is there a mechanism to minimiz
e loading effects?
>
>
Just a guess, but I would assume they use some sort of positional
feedback to handle compressability/loading effects (or use VERY high
pressure in a push/pull system).
Keith Levkoff
klev...@panix.com
John J. R. Irvine
> [snip]
> I presume that position of a robot arm (for example) will vary with applied
> load (ie air is compressible). Is there a mechanism to minimize loading effects?
_Feedback_ of course!
John J. Irvine
Dept of Cybernetics (the f******k addicts ;-)
University of Reading
UK
Onat Ahmet
klev...@panix.com writes:
>> In article <3pg40b$o...@su102w.ess.harris.com> patk...@harris.com writes:
>> >Are 'air muscles' the same as air cylinders (produced by Bimba, etc)? Are any details available on the valves used? I presume that position of a robot arm (for example) will vary with applied load (ie air is compressible). Is there a mechanism to minimiz
>> e loading effects?
Air muscles have been developed by Kawato in Japan. His main research
is on how animals (humans) control their joints.
These look like long baloons inside webbing. Because of the special
weawe pattern, the whole thiing contracts with increased air
pressure, and extends(loosens) otherwise. They must be used in
pairs in pull pull applications (as in a human).
>> >
>> >
>>
>> Just a guess, but I would assume they use some sort of positional
>> feedback to handle compressability/loading effects (or use VERY high
>> pressure in a push/pull system).
Positional control in pneumatic systems is very difficult, and is
usually avoided where other options are available.
Making rigid structures by using internal forces is
called variable compliance and is being researched currently(not only
for pneumatic systems, but also with motor controlled mechanics).
>>
>> Keith Levkoff
>> klev...@panix.com
Ahmet ONAT
Mark Worsdall
The SHADOW air muscle is a new actuator that is small, light,
simple and friendl.
It has no stiction, is easily controllable and is exceptionably
powerful. Plus: it's cheap.
The SHADOW air muscle was originally designed to power a high tech,
six-foot tall,two-legged android but now it is also on sale to
secondary schools that have pupils only two-thirds that height
and no knowledge of robotics. The British inventor of the SHADOW
air muscle claims it has wide ranging applications across industry,
education and the world of consumerism, and that it fits in
comfortably at all points on the technological scale.
The muscle
The SHADOW air muscle - patented in 1991 - consists of a rubber
tube covered intough plastic netting which shortens in length
in the manner of a human musclewhen inflated with compressed air
at low pressure. It is powerful. A typicalSHADOW air muscle has
a power-to-weight ratio of about 400:1, vastly out-flexingboth
pneumatic cylinders and DC motors that can claim a ratio of only
about 16:1. The smallest air muscle, at just 9mm in diameter,
has the strength, speed and fine stroke of a finger muscle in a
human hand. Quiz anyone hanging off a rocky cliff by their
fingertips to appreciate the significance of this. A air muscle
30mm in diameter is capable of lifting 210 Kg (three people) at
a pressure of only four bar, while the largest muscle (60mm)
has enough power to do serious damage: it could probably pull
down a brick wall.
The SHADOW air muscle is easily controllable. It is capable of fine control,
rapid movement and high power, in any combination or all at once. It exhibits
all the characteristics of the human muscles that give our limbs the potential
for incredible control. For example, computer users find a mouse so convenient
because the pointer can be made to rush all round the screen yet instantly
slow down for precise movement - easy, because the human muscle can change
from fast to slow and powerful to gentle at the drop of a hat. The SHADOW air
muscle can do the same. With two (or more) air input tubes, one fat, one thin,
the rate of air is easily adjusted to suit different grades of precision.
The SHADOW air muscle is inherently compliant. It is soft, flexible, safe and
the smallest weighs in at a featherweight 5 grammes. It can get wet, operate
under water, be filled with liquid and even works happily bent round a curved
object. Compliance is vital for environments in which humans, animals and
delicate objects are involved. Any domestic robots of the future will find
themselves in just such an environment but even now industrial robots can
benefit from compliance. Operations on curved surfaces, such as polishing, are
carried out far smoother using a compliant actuator. Babies, eggs, old age
pensioners and most other household objects are just a few things that would
choose a compliant robot any day over a rugged metal Dalek, even without
the poison gas.
The SHADOW air muscle has several mechanical advantages where reciprocal
motion is concerned, in both nature and manufacture. A hand moving out
and back, a foot moving backwards and forwards (walking) and fingers opening
and closing are all reciprocal movements, as are drilling heads moving up
and down, jaws opening and closing and work taken up to a rotating wire
polisher. Rotary motors are not good actuators in these situations so
hydraulic or pneumatic pistons are commonly employed. But hydraulics
are heavy and cumbersome and pneumatic pistons suffer from stiction, making
proportional control virtually impossible. The lightweight SHADOW air muscle,
on the other hand, is linear like a piston yet has low friction that is
completely constant. Proportional control becomes a picnic.
Take reciprocal motion, add compliance, mix well and you get an actuator that
is also kind to its neighbours: a SHADOW air muscle can't take a potentiometer
beyond its range by mistake, or rip wires and plugs out by overshooting.
New operating modes show doubling of pull compared to earlier models after a
decade of development, SHADOW air muscles have improved in performance thanks
partly to a novel process in their manufacture which is the subject of a
current Patent Application. Compared to earlier models, power is increased
by between 10% and 100% over the range of pull.
The graphs NOT illustrated here are of contraction in millimetres against
inflating pressure in kiloPascals.
In both graphs pressure is increasing on the lower part of the hysteresis.
The advantages of the preprocessing are clearly illustrated, up to eight
times the contraction (depending upon the pressure in the muscle),
significantly less hysteresis, a greater initial rate of contraction,
and greater overall contraction.
The tests were carried out on 270mm by 30mm (nominal diameter) muscles
under a constant load of 10kgf, a relatively light load. Note also the
smoother response of the treated muscle during the last stages of
relaxation.
The SHADOW air muscle --- APPLICATIONS.
Industrial
Actuators with proportional and compliant control can easily be
incorporated into machines, for example bringing work up to a rotating
wire brush for flash removal or allowing delicate parts to be handled.
Medical.
As an externally attached prosthetic muscle.
For Rehabilitation, as part of a compliant moving machine to allow patients
to maintain joint mobility.
Aids for the disabled where compliance is vital e.g.
- Turning page of book
- Feeding aids.
- Opening or closing a window.
- Adjusting Venetian blinds
- Opening cupboards
- Unscrewing bottle tops.
- Adjusting angle of bed or chair.
- A full body hoist
Robotic.
Walking machines
Arm, hands
Educational
Children can use SHADOW air muscles to build moving devices for their Design
and Technology projects. They are much easier to use than other actuators.
Other uses:
1. Teaching biology
2. Teaching leverage.
3. Automatic Greenhouse and similar class projects.
Rescue & recovery
A large SHADOW air muscle or muscles could pull a car out of a ditch or
lift fallen beams or girders from a trapped accident victim.
Remote operation
Door or gate opening/locking, ventilator opening, camera moving (to swivel,
pan and tilt), operation of devices with either time delay or photocell
triggering. For example, animals could be fed at prescribed times, or when
they break a light beam, using SHADOW air muscles to open a lid or pour feed.
TV or Film Studio
Puppets, moving models, walking dinosaurs and other special effects; or
remote control of studio equipment. For example, SHADOW air muscles could
be temporarily hooked to, say, the "barn doors" of a spotlight to open or
close them for a particular effect.
Photographic Studio
Still Life photographers often need a controlled repeatable movement, e.g.
pouring cream from a jug. A SHADOW air muscle can be taped to the jug or
other object requiring movement.
Shop window display
Even small or simple movements of mannequins or other objects in a shop
window attract attention: or just a sign saying "SALE NOW ON" that pops
up from time to time.
Multi-position Armchair
Fill the SHADOW air muscles with water. Use them in pairs so that as the
back of the chair tilts back, water from one SHADOW air muscle is squeezed
out to fill another.
1. This acts as a damper
2. A simple valve on the connecting tube allows the user to lock position.
3. A very small pump makes the chair power-driven
(for those with danaged human muscles or just the lazy)
4. A computer and some simple sensors would allow the chair to move
rhythmically and soothingly, rather like a rocking chair.
Cheap hydraulic brake system e.g. for bicycles
Water filled, one SHADOW air muscle is master, another is slave.
Virtual Reality (Teleprescence) set
(As the operator turns his or her head, a remotely mounted camera is
turned by the same amount. Note: the SHADOW air muscle would allow sudden
movements of the head to be echoed)
Other applications:
SHADOW air muscles go for gold
Hexadon is a six-legged walker built out of Lego that marches on air. It is
currently preparing for the First World Robot Games, to be held in Glasgow
Summer 1995. The SHADOW air muscles that power each limb leave motors on
the starting blocks and one of the reasons for this is the ease of
attachment. Motors need critical positioning; either gear-wheels,
drive-belts or chains etc are needed to transmit the drive, or the motors
themselves need to occupy space close to the pivot and this is a popular
spot - on a robot arm there will be cables, tubes or tendons jostling for
a through-route to the tip of the limb, while bearings and potentiometers
struggle for a seat on the axis. SHADOW air muscles avoid this crowding
by hooking on, unobtrusively, to a convenient point somewhere else and
precise alignment is not a concern, leaving the axis free. Another
boon: with air muscles a spring or even a simple rubber band, rather
than complicated electronics, can restore the limb and the air muscle
to the original position.
Application (low tech): The SHADOW air muscle in schools
The first area in which SHADOW air muscles have been commercially
exploited is education. Shadow sells a kit consisting of several
actuators, sensors, an interface control board and computer software.
The kit is designed to fill a resource gap created by the introduction
of a new section in the National Curriculum, called Control and
Measurement'. The SHADOW air muscle pack enables pupils to build simple
devices like robot fingers or combine several air muscles to form complex
machines. They control their creations on a classroom computer using
graphic icons in a simple-to-use, Windows-style environment or for more
advanced users, the programmers interface (a commandline) package.
The SHADOW air muscle is complemented by a proprietary load cell
(pull sensor) that is designed to produce large changes in resistance in
the K-ohm range. With such a large response range, no amplification is
necessary, and the problem of noise associated with conventional
strain gauges is avoided.
Application (high tech): the Shadow Robot Project
SHADOW air muscles of sizes large and small can be found up and down
the legs of a six-foot tall, prototype android robot, under construction
in a research workshop in North London. The robot, called Shadow, is the
project of a voluntary group that was initiated by the inventor of the
SHADOW air muscle, Richard Greenhill. After years working solo, in 1987
he was joined by an engineer, David Buckley, who designed the Shadow
robot's legs. Now the group is 14 strong and aims to build a
general-purpose domestic robot that can perform household chores like
washing up and cooking. The long term objective is to make the robot
capable of most things humans can do, from driving cars to
fighting fires.
The robot's frame is made from wood that is strong enough to be
supportive while light enough to be moved easily. The current state of
the Shadow robot is described by David Buckley as like a three-month
old bab. Using the SHADOW air muscles, it can move its legs about but
has yet to learn how to balance and walk. A walker program based on a
neural network systemis under development.
Human body
The Shadow robot is modelled closely on the human body because,
says Richard Greenhill:
Everything in civilisation, from cities and roads to houses and cars,
is designed to be used by humans. There is simply no point in building
a Dalek. Their plan to conquer the universe was doomed from the moment
they met a flight of steps. The incredible range of motions and dexterity
required to clear cluttered table after a dinner party is something humans
do, modestly, with great efficiency and success, even after wine. A rigid
robot, with an arm made from servos and control rods and a cousin that works
in a car-painting factory, has no chance in the dinner-party test. The
Shadow robot, using the human-coined soft approahas a head start.
Conclusion: The SHADOW air muscle's role
The SHADOW air muscles described earlier are virtually human substitutes;
they have the strength to hang off cliff faces, the compliance to lift
babies and the controllability to operate a computer mouse. They are an
essential element in the humanising of robotics and are ideal for
controlling any sort of device where compliance and positional control
is desired.
For more details on the above:-
Contact Richard Greenhill 0171 700 2487 daytime UK
or
FAX 0171-607-7151 (UK) Anytime.
Paul M Atkinson
Kurt Mahan
|> Interesting information. What is the cost of the educational package of Shadow materials? Also, are more specific details available, a picture or schematic of an air muscle attached to a joint for example? Any magazine reviews yet?
|>
I'd also be interested in the pricing. Also is there anymore information
on the Hexadon robot?
Kurt
--
/*
* This version of Kurt Mahan is currently being evaluated. Words he speaks
* are those of him only and not those of Novell or anybody else.
*
* Kurt Mahan
* kurt_...@novell.com
*/
ray landers
: Followup to initial SHADOW article follows:-
[snip]
WELL DONE!!
this is great.
i'm realy glad to see some one putting this to work.
i remember putting a balloon in one of those "finger trap" thingies when
i was a kid, and noticing that it got shorter as it got bigger around, as
well as bigger around as it got shorter. depending on how you applied
force to it.
at the time it seemed that there was something significant about that,
but i didn't know exactly what it was good for. they were only made of
woven straw. i quickly wore mine out, and then got in trouble for wearing
out the ones that belonged to my sisters. i was about 7 at the time.
i'm glad to see somebody figured it out.
good work, and i'm eager to hear how thing go on this project. please try
to find time to post a progress report once in a while.
ray
--
ra...@netcom.com
From one of the "HEAD KOOKS" at ftp violet's ansi art from
Rhinoceros Kitchen Ray ftp.netcom.com pub/ra/rayl
check the README file there
______ .(((()
| | (_ '\)
| | __/ \()!
.-|______|. ____(|___/ |!
:__|____|__|____| : |!
:|_____________| _;_/\__|!
:| |/ ____)!
:| | \!""""!
:| _________ |\__/)____!
#|_| |_| (/! !
''''''''''''''''''''''''''''
Mark Worsdall
: Mark Worsdall (jay...@hinwick.demon.co.uk) blessed us with the
:
: [snip]
:
: WELL DONE!!
:
: this is great.
:
: i'm realy glad to see some one putting this to work.
:
: i remember putting a balloon in one of those "finger trap" thingies when
: i was a kid, and noticing that it got shorter as it got bigger around, as
: well as bigger around as it got shorter. depending on how you applied
: force to it.
: good work, and i'm eager to hear how thing go on this project. please try
Soon, more members of the Shadow Robot Project will be on the net.
One of our programmers (Richard Walker) is the next one to come on
line. He is currently developing a Coffee cup collecting robot.
Basically it will get you a cup of coffee from the coffee machine
and deliver it to you. He hopes to give the Robot it's own
Email address, so that you can email a request for coffee. The
next step on from finger the coke machines! Ofcourse it will
know from your email address that you are out of the building
and will not deliver to you! Well, we will just have to see if
the Email part of the project will work! Fingers crossed!