Transcript Artificial Muscle Presentation.ppt

Artificial Muscle
Kori Brabham
Misti Marr
Andy Smith
Paul Lee
Natural vs. Artificial
Muscle
What does a natural muscle do?
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It is a contractile organ.
It consists of fibers which “actuate” force and
motion in response to nervous stimulation.
How does it work?
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Muscles contract by the chemo-mechanical action
of the proteins actin and myosin.
Joints of the body are arrayed such that they
comprise muscles which oppose each other.
Natural vs. Artificial
Muscle
How can we develop replacements for the
natural muscle?
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Develop biomimetic actuators.
Emphasis on implantable technologies (not on the
the forefront now).
What do we have to work with?
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Electrical/pnuematic servos (robotic limbs, late
1940’s-present).
New materials.
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Synthetic polymers
Carbon
What constitutes a
muscle?
Any system or combination of sub-systems can be
considered a “muscle”:
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hydraulic/pneumatic cylinder.
electromagnetic servo.
biological muscle tissue.
In short, anything which accomplishes actuation
under the command of a stimulus.
Muscles primarily exert energy (ATP) to bring about:
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motion, acceleration (v/t or 2x/t2).
force application (F=m.a).
Muscles Revisited
Muscle cells are highly specialized for
contraction.
ONLY contract and relax
 Abduction and adduction
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Actin and myosin vary in amounts and
configuration, depending on cell
function.
Three types
Skeletal – voluntary and striated
Cardiac – involuntary, striated, and
branched
Smooth – involuntary and unstriated
The Design of Natural
Muscle
Muscles are simply transducers

They change the chemo-electric signal
from nerves to mechanical energy.
Artificial muscles should be similar in
resilience and in the ability to produce
large actuation strains
http://www.unm.edu/~amri/protect/
Brief Timeline
1619 - Descartes postulated that
sensory impulses activated muscle
(reflection)
1780 - Galvani noticed frog muscles
would contract with electrical apparatus
Brief Timeline (cont’d)
1968 – Rubber
artificial muscle
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Invovled several
thread running along
a longitudinal axis
Compressed air is
injected
Brief Timeline (cont’d)
1968 - Model
Postural Control
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A biped walking
machine is required
to maintain it’s
balance while
standing and walking
Artificial Muscle—An
Overview
Many types of artificial “muscle”.
McKibbin muscle actuators
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Inflatable air tubes, delivering large force at a low
frequency.
PAN-chemically stimulated by pH change.
Electrically Stimulated “Tissues”
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IPMC
Solenoids (not presented)
Piezo-active polymers and ceramics (not
presented)
A Review of Current
Technology
The McKibben Artificial Muscle
History
First developed in the 1950's by American physician
Joseph L. McKibben
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originally intended to actuate artificial limbs for amputees
More recently was commercialized in the 1980's by
Bridgestone Rubber Company of Japan
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patented and called “Rubbertuator”
Presently the Shadow Robot Group of England
manufactures these actuators for robotic applications
How it’s made
Consists of an internal bladder
Bladder is covered by a braided mesh shell
Attached at either end to tendon-like structures
How it works
Internal bladder is
pressurized
Bladder expands in a
balloon-like manner
against the braided shell
Shell constrains the
expansion to maintain a
cylindrical shape
As the volume of the
bladder increases due to
the increase in pressure,
the actuator shortens and
produces tension
Advantages of the McKibben
Artificial Muscle
High force to weight
ratio
Lightweight
Low Cost
Smooth
Size availability
Flexible
Powerful
Damped
Effective
Comparison to biological
muscle
Force-length properties are reasonably close
Force-velocity properties are not close
 a device called a hydraulic damper that operates
in parallel with the McKibben muscles has been
created
McKibben muscles are attached to a spring-like
device that simulates the tendon properties and
energy storage of a real muscle
Ionic Polymer-Metal
Composite
How it’s made
Composed of a perfluorinated ion exchange
membrane
Consist of a polymer matrix that is coated on the
outer surface with platinum in most cases (silver and
copper have also been used)
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coating aids in the distribution of the voltage over
surface
Made into sheets that can be cut into different shapes
and sizes as needed
How it works
Uses electricity (electrodes,
conductors, etc.) to operate
A circuit is connected to
surface to produce voltage
difference, causing bending
Strips can bend and flap
dramatically which allows
movement
Advantages of IPMC
Light
Compact
Driven by low power
and low voltage
Large strain capability
Comparison to biological
muscle
High fracture tolerance
Large actuation strain
Inherent vibration damping
Responds to electricity with elasticity and
responsiveness similar to those shown to biological
muscle
Nanotube Artificial
Muscle
Invented by Max Plank
Institute, produced by
AlliedSignal.
Based on Carbon
nanotubes (bucky
tubes).
Sub-microscopic
Carbon sheets (formed
into tubes) filled with
electrolytes.
Nanotube Artificial
Muscle (cont’d)
When a voltage is
applied the sheets
contract to do work.
Possible limitation:
electrically actuated.
Being investigated by
Defense Advanced
Research Projects
Agency (DARPA) as
“bucky paper”.
Polyacrylonitrile (PAN)
Combination of gel and
plastic. Tough.
Contracts under pH
changes.
Contraction occur in 20
ms to a -20% strain.
Very similar to human
muscle in speed,
exceeds human muscle
in max force per cm2
(2x).
Polyacrylonitrile (PAN)
(cont’)
Must be surrounded
by solutions in latex
tubes.
Some models have
been developed
which simulate
muscle movement.
University of NM
project.
Electro-active Muscle
Transducers
Uses compliant electrodes to
electrically stimulate electroactive elastomeric materials.
Produce strains in excess of
100%, and pressures greater
that 100 psi.
Spherical joints have been
developed based on the
actuator.
Developed by SRI
International, Inc.
Electro-active Muscle
Transducers (cont’d)
AKA Electrostrictive or dielectric elastomer.
Exhibit a mechanical strain when subjected to
an electrical field.
Striction capability exceeds piezoelectric
ceramics.
Most common are PMMA-based.
Produce a positive force/expansion.
Use: tiny robotic muscles.
A Novel Use for AM
Smart implants with tiny
perforations that contain
a pharmaceutical,
plugged by artificial
muscles.
The implant has tiny
sensors which sense
blood concentrations of
certain chemicals.
A Novel Use for AM
(cont’d)
The artificial muscle
then will shrink to allow
a drug to pass freely.
When concentrations of
the sensed chemical
rises in the blood, the
muscle then relaxes to
plug the holes a gain.
Honorable Mention
Replacement: Prosthetic
Limbs
Started as passive replacements to fill clothing or act
as support.
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Archeological evidence of prostheses in ancient India and
Egypt--Queen Vishpla, Elis.
Infection and blood loss.
1600’s-1800’s
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Great increase in health technology: styptic antibiotics,
anesthetics, blood clotting chemicals.
Prosthetic units were developed with lighter weight and
greater articulation (motion learned and controlled by
amputee).
1940’s-1980’s – Emphasis on actuation.
1980’s-Present – Emphasis on realism.
Replacement: Prosthetic
Limbs (cont’d)
Number of Companies that specialize in
prosthesis/orthotics:
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North Shore Orthotics-Prosthetics, Inc.
Ohi, SCOPe, many others.
Limb replacements are actuated:
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By other existing muscles directly.
By EMG generated by nearby existing muscles
Balance.
Artificial Muscle
Applications in Robots
Types of Robots
Miniature robots
Wall climbers
Exploring rovers
Miniature Robots
Submersible bots
with plastic muscles
Ability to someday
pick up single cells
Positive and
negative ions shrink
and swell the
polymer
Wall Climbers
Air Rubbertuator
Capable of difficult
inspections
Aircraft
Bridges
Nuclear power plants
Obstacles, inclines,
stairs, vertical
movement.
Robots in Space
Ability to probe, dig, photograph and
analyze
No gears or complex mechanical
systems
Lighter and less complex robots
Smaller
Not sensitive to dust
Capabilties
Grasping
Wiping
Muscle groups working together
Grasping
Electric charge
applied to plastic
ribon
Charged particles
pushed to one side
lengthens that side
Wipers
Two-way wiping
motion produced
Applications onto
cameras or sensors
Muscles Working
Together
Creates more than
one motion
Bionic men and
women???
Could replace
human muscles
Legs and Wheels
Able to handle most
terrain
Durable
Reliable
Not as good as four
legs
A Way of the Future
Cheap
Durable
Lightweight
Conserve Power
References
Electroactive Polymer Actuators webpage
Artificial Muscle Research Institute
SRI International, Inc.
Opthalmatronix, Inc.
Ohio State University
www.spacedaily.com
Max Planck Society
University of New Mexico -- cape.uwaterloo.ca
BBC News
Science Daily
Discovery Channel