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FLEXIBLE LIGHTWEIGHT SHAPE MEMORY ALLOY ACTUATOR FOR EXO-SKELETON SYSTEMS
ESTEC, 11th May 2015
Marcelo Collado R&D Programmes STAMAS Project Coordinator
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ENGINEERING
• Space R&D
• Advanced Engineering Services
• Technology Transfer (Spin-in/Spin-off)
• Medical products
Leganés (Madrid)
Seville
Frankfurt Oder
MICROELECTRONICS • Mixed-Signal ASICS (full supply chain) • FPGA development • Interface Components • Electrical and Radiation Characterization Test Services
SHAPE MEMORY ALLOY TECHNOLOGIES • High Temp SMA (SMARQ) • Non-Explosive SMA Actuators • Valves • New SMA applications
SPACE SCIENCE • Sensors • Mechanisms • Planetary exploration • Robotics
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Space Wireless sensor networks for Planetary Exploration
Smart technology for artificial muscle applications in Space
R&D FOR SPACE
SEPHY Space-qualified Ethernet Physical Layer Transceiver
REACT REsettable Hold-Down and Release SMA ACTuator
LIBRA Development of a space-qualified rad-hard mixed-signal library (IHP SGB25RH)
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OUTLINE
Introduction
Spaceflight problems addressed
Proposed solutions
– Leg-suit demonstrator
– Hand-suit demonstrator
Lightweight flexible actuators
– Description
– Test Plan & Results
Conclusions and future works
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STAMAS SMART TECHNOLOGIES FOR ARTIFICIAL MUSCLE APPLICATIONS IN SPACE
FP7 PROJECT EC-GA 312815
WWW.STAMAS.EU
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SPACEFLIGHT PROBLEMS ADDRESSED Weightlessness changes the normal
distribution of blood.
The blood tends to shift to the upper part of the body.
The heart decreases its size and the number of blood cells.
The circulation in the lower limbs works worst, producing loss of muscle and bone mass in legs.
The lack of gravity causes weakening of the bones through several processes:
Decalcification.
Bone cells malfunction.
Exercise or pharmacological supplements not fully effective.
Weightlessness causes physical deconditioning due to:
The lack of efforts.
The physiological variations generated in microgravity
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SPACEFLIGHT PROBLEMS ADDRESSED
Walking on Earth, human legs find irregularities in the terrain.
Proprioceptive function causes that many secondary muscles act to restore stability.
Current exercises on board don’t allow to train this function.
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SPACEFLIGHT PROBLEMS ADDRESSED
Spacesuits for Extra-Vehicular Activities (EVA) cause damages and problems in the hands of the astronaut: Premature fatigue. Loss of strength and dexterity. Nail damages.
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PROPOSED SOLUTIONS: ACTUATED SPACE SUIT Biological feedback : Bio-cooperative control of physiology
o Sensors to monitor the user parameters.
o Control of exercising intensity for optimization
of exercise.
o Detection of the user movements to control
the actuations.
Flexible system to allow freedom of movements.
o No rigid and massive structures in opposition to exoskeletons.
o Wearable system.
o Exercising complementary to current devices.
o Possibility of continuous exercising during life in space.
Lightweight design.
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Use of actuators based on smart materials: Artificial muscles
o Shape Memory Alloys (SMA)
Shape Memory Effect
Pseudo-elastic effect
o ElectroActive Polymers (EAP)
Dielectric Elastomer
PROPOSED SOLUTIONS: ACTUATED SPACE SUIT
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Biomimetic concepts: Exo-muscular systems
PROPOSED SOLUTIONS: ACTUATED SPACE SUIT
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PROPOSED SOLUTIONS: ACTUATED SPACE SUIT System Architecture
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Leg suit to mitigate some effects of
microgravity:
o Exercising device.
o Inside the spacecraft.
Hand suit to improve the hand tasks during
Extra-Vehicular Activities:
o Assistive device.
o Outside the spacecraft.
PROPOSED SOLUTIONS: ACTUATED SPACE SUIT
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LEG SUIT DEMONSTRATOR General overview
Functions:
o Musculoskeletal degradation countermeasures based on active devices.
o Control the exercising intensity depending on the user biological parameters.
o Provide feedback to the user to adapt the exercises.
The Leg-suit is composed of 3 actuating subsystems:
o Ankle Lateral Actuation System (ALAS):
Robotic ankle device for exercising, based on SMAs.
o Smart Elastic Bands System (SEBS)
Semi-passive system for the legs exercising, based on SMAs.
o ElectroActive Polymer Bands (EAPB)
Device for compression of limbs, based on EAPs.
Alternative compressions on the thigh to modify the blood flow and pressure.
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LEG SUIT DEMONSTRATOR – ACTUATORS
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Main Functions:
o Assist the astronaut during EVA missions,
reducing hand fatigue and increasing the
performance during handling tasks.
o Detect the movements intention of the astronaut’s
hand and follow them.
o Compensate the stiffness of the glove, by
producing an actuation to help to the finger
flexion.
The Hand-suit is composed of just one element:
o A Hand Exo-Muscular actuating System (HEMS).
6 DoF.
HAND SUIT DEMONSTRATOR
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HEMS actuating system
HAND SUIT DEMONSTRATOR
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FLEXIBLE SMA ACTUATORS Description
o SMA actuators composed by
o SMA wires
o a metallic sheath
o PTFE insulation
o Allows flexibility
o Versus straight SMA wires configuration.
o Enhanced cooling rate
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FLEXIBLE SMA ACTUATORS Description
o SMA actuators composed by
o SMA wires
o a metallic sheath
o PTFE insulation
o Allows flexibility
o Versus straight SMA wires configuration.
o Enhanced cooling rate
Test Plan
o Flexible SMA actuator
o Cooling rate test for different configurations
o Flexible properties test: Force and stroke at
different bent angles
o Control of Flexible SMA actuator
o Different control approaches: force or stroke
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FLEXIBLE SMA ACTUATORS Test Plan
o Flexible SMA actuators
o Cooling rate test for different actuator configurations
o Different sheath configurations
o Active vs passive cooling
o Flexible properties test:
o Output Force at different bent radius and angles
o Stroke at different bent radius and angles
o Control of Flexible SMA actuator
o Different control approaches:
o Force control
o Stroke control
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FLEXIBLE SMA ACTUATOR HEMS Actuator test over an artificial hand
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Test Results
o Flexible SMA actuators show good behaviour.
o Improved cooling rate (freq).
o Good results with bending angle and
radius: small differences in maximum
force and stroke at the output.
FLEXIBLE SMA ACTUATORS
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FLEXIBLE SMA ACTUATOR Controller Test over an artificial hand
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CONCLUSIONS Benefits: o Flexible SMA actuators
o Flexible low weight system,
o Wearable: Flexible actuators allow the freedom of movements.
o Compactness: Allows larger stroke in the same overall volume.
o Improved frequency (with slight increase in consumption).
o System level: o Collaborative system, controlled by the user biological signals.
o Improvement of astronauts exercising on board.
Exercises on secondary muscular groups.
Continuous exercising.
Reduction of the fatigue of the astronaut: increase the time of EVA missions.
Limitations: o SMA is a thermal process – Cooling time limits frequency. o Power consumption.
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Future applications:
o Exo-skeletons and wearable devices.
o Actuators for robotic systems
o Extreme environments applications
o Applications with critical volume and flexibility restrictions.
o i.e.: Snake-like robots, active structures, small manipulators, ….
o Transfer to other fields and markets
o Rehabilitation
o Handicaps assistance
o …
CONCLUSIONS
Marcelo Collado R&D Programmes STAMAS Project Coordinator mcollado@arquimea.com
Thanks for your attention!
http://www.stamas.eu
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