An Astronaut ‘Bio-Suit’ System: Exploration-Class Missions Professor Dava J. Newman, Ph.D.*+ Professor Jeff Hoffman* Kristen Bethke*, Joaquin Blaya+, Christopher Carr*+, and Bradley Pitts* *MIT Department of Aeronautics and Astronautics
+Harvard-MIT Division of Health Science and Technology
MIDÉ Technologies, TAI 6 November 2003
Image, © Michael Light, Full Moon
Industry Partners Trotti & Associates, Inc. (TAI)
MidĂŠ Technology Corporation is a R&D company that develops, produces, and markets High Performance Piezo Actuators, Software, and Smart (Active) Materials Systems; primarily for the aerospace, automotive and manufacturing industries.
TAI is a design consulting firm helping private and public organizations visualize and develop solutions for new products, and technologies in the areas of Architecture, Industrial Design, and Aerospace Systems. Award-winning designs for: Space Station, South Pole Station, underwater habitats, ecotourism. Phase I partner.
Advisory Board Dr. Chris McKay, expert in astrobiology, of NASA ARC. Dr. John Grunsfeld, NASA Chief Scientist, astronaut. Dr. Cady Coleman, NASA astronaut. Dr. Buzz Aldrin, Apollo 11 astronaut.
Overview • • • •
Space Exploration Performance Design Concepts Systems Approach
Space Suit Design: Motivation • Extravehicular Mobility Unit (EMU) – – – – – – –
Designed for weightlessness Pressurized suit (29 kPa, 4.3 psi) Life support system (O2, CO2, etc.) 2 pieces: pants, arms & hard upper torso Donning and doffing are highly involved Adequate mobility for ISS NOT a locomotion/exploration suit
• Number of EVAs (1965-2000) – 600-surface-day mission
Space Suit Design: Methods Analyze Past Performance • Metabolic Cost, Voice Communications, Tool Usage • Understand limitations (physical, cognitive, environmental., ops.)
New Solutions • Information Management: Wearable Computing, Planning, Geologic Tools [Carr, Schwartz, Newman, 2001]
“Biosuit”
• Skills-based training vs. task-based • Metabolic Cost Model
Advance Concepts
Mark III: Field geology in the Mojave Desert
59kg suit + 15 kg life support 57.2 kPa/8.2 psi
30kg suit
12 kg suit
26.2 kPa/3.8 psi
26.2 kPa/3.8 psi
Mechanical CounterPressure?
Background and Contributions Space Suit Mobility Performance & Modeling
Bio-Suit Concepts
Iberall, 1964
Biomechanics & Energetics
Mechanical Counter Pressure
Suits
Newman et al., 1993, 1994, 1996
Webb, 1967 Clapp, 1983 Tourbier, 2001 Korona, 2002 Eiken, 2002 Pitts, Newman et al., 2001
Dionne, 1991 Abramov, 1994 Menendez, 1994
Human Subjects Morgan et al., 1996 Newman et al., 2000 Schmidt et al., 2001
Modeling Iberall, 1970 Rahn, 1997; Schmidt, 2001; Carr, 2001
Enhanced Performance Blaya, Newman, 2003
Space Exploration (e.g., field geology) • Look to future (1) Mobility and (2) Performance • Understand exploration techniques • Learn from past expeditions
Lewis and Clark
Present Day Field Geology
Lunar Field Geology, Past & Future © Michael Light, Full Moon
Pat Rawlings (NASA)
Mission and Traverse Planning (1) Inputs
(2) Traverse Evaluation
(3) Outputs and Metrics
Automation in the planning process?
[Carr, Newman, Hodges 2003]
Method (1) Terrain Model, Spatial and Temporal Characteristics; Sun Geometry (2) Predictive and parametric analysis including automated validation of ‘mission rules’.
Results (3) Outputs and Metrics: Traverse model, slope statistics, accessibility, visibility, energy consumption, low-energy direction of travel, and sun-relative angles and sun-score.
Planetary Exploration Example Example: Apollo 14 2nd EVA Visibility problems with the planned traverse. Actual traverse, astronauts failed to find Cone Crater, geology stations C’ and C1
Modify traverse improves access and visibility of cone crater Provides better situational awareness (lunar module visibility) and reduced sun score Estimate energy consumption within ~10% of Apollo estimates
Visibility from Lunar Module [Carr, Newman, Hodges 2003]
…from Geology Station C’
…from Geology Station C1
…from modified Geology station
Performance
Augmented Human Performance • • •
Problem: Drop foot, pathology Causes: Stroke, Cerebral Palsy (CP), Multiple Sclerosis (MS) Major complications - Slap foot after heel strike - Toe drag during swing
• •
Design: Polypropylene AFO Sensors – Potentiometer: Ankle Angle – 6 Capacitive Force Sensors • Ground Reaction Force
•
Series Elastic Actuator (SEA) – Suited for human-like tasks • Low impedance • High Power Density • Filters noise and backlash
Active Ankle Foot Orthosis
Impedance Control: Drop Foot Contact 1: Adaptive biomimetic1 torsional spring to minimize slap Contact 2: Minimized impedance Swing: Adaptive biomimetic2 torsional spring-damper to lift foot for toe clearance
1. 2.
M. Palmer, “Sagittal Plane Characterization of Normal Human Ankle Function Across a Range of Walking Gait Speeds,” in Mechanical Engineering. Cambridge: Massachusetts Institute of Technology, 2002 J. B. Blaya, “Force Controllable Ankle-Foot Orthosis (AFO) to Assist Drop Foot Gait,” in Mechanical Engineering. Cambridge, MA: Massachusetts Institute of Technology, 2002.
Summary: Augmented Performance Engineering methodology: variable-impedance control - Slap foot was reduced - Swing was more biologically realistic
Design Goal: modulate joint impedance to gait phase and speed Unlike current devices, variable-impedance control adapts to user 1. Step-to-step variations due to speed changes 2. Long-term changes due to rehabilitation
Personal and subjective benefits
Design Concepts • Mechanical Counter Pressure (MCP)
Space Activity Suit Accomplishments: - Up to 22.7 kPa (3.3 psi, 170 mmHg) over entire body - Greater mobility - Lower energy cost - Simplified life support Areas for Improvement: - Don/Doff time and difficulty
Webb 1971
- Edema and blood pooling due to pressure variations
SAS: A Closer Look
Pressure Skin Requirements Physiological Requirements – Partial pressure O2 > 20.0kPa (2.9psi, 150mmHg)* – Body surface pressure = breathing pressure
Mobility Requirements
S
– Constant volume design • Small separation between suit and body Æ Mechanical Counterpressure – Thin materials – Conflicting requirements
dA
suit body
dv = S dA
T = pr Pressure produces tension and vice versa. p = T/r
Webb, 1967, 1971
MCP Don/Doffing • SAS body surface pressure was created by strain energy of material • Work must be done in order to store this energy The SAS was very hard to get into! • Energy (or tension) could be created AFTER donning is complete by: Shrinking garment
OR
Cam Brensinger for TAI
“Enlarging” body
Creating MCP: Channel Design •Pressurized channel pulls tension once the suit is donned and pressurized. •Skin-tight, inelastic garment minimizes the volume of the suit and transmits tension. •How can an inelastic garment allow mobility? •Requirement on E?
‘Bio-Suit’ Concepts: Design Trades
Revolutionary Design: Bio-Suit Mechanical Counter Pressure (MCP) – – – –
Skin suit cf. pressure vessel Greater flexibility, dexterity Lightweight Easy donning and doffing: {clothing vs. strapping on spacecraft (ISS suits)}
Electro-Mechanical assistance – Augments astronaut’s capabilities – Decreases the effects of microgravity deconditioning – Assisted locomotion 1G (AAFO)
Suit Components Bio-Suit multiple components: – – – – –
The MCP bio-suit layer A pressurized helmet Gloves and boots A hard torso shell A life support backpack
Components are simple, interchangeable, and easy to maintain and repair Idea: Custom-fit skin suit to an individual human/digital model DW = DWp + DWe DWp - Minimize through design DWe - Bending (design) and Strain Energy (min. or max E)
Producing MCP •
Active Materials – Piezoelectrics • Small-scale actuators, NOT applicable to bio-suit
– “Smart” polymer gels • Expand with body heat, voltage, or pH • Thermal layer promise
– Shape Memory Alloys (SMA) • Voltage toggles shape between two states: expanded and contracted • TiNi, Nitonol (titanium nickel) – Human force levels – Not entire suit (mesh), promise for hybrid concepts
Active Materials Database • “New” field of active materials – many competing systems types
• Designers need method of easily comparing various materials and impact on system design • Mass, Volume, Cost; Energy (Power); Performance • Realistic operating environment
Material Comparison
Fr
eq
ue
nc
y
(H
z)
Stress (MPa)
• Stress, Strain, and Bandwidth (log scale)
Strain (%)
Systems Level Impact • Certain active materials may look attractive when considering raw material energy density or basic actuator bandwidth. • However, true material comparisons can only be made upon considering entire system: – Material energy density – Coupling efficiencies – Cost, weight, and efficiency of power electronics.
• For example, SMAs have tremendous energy density but very poor electrical efficiency.
Paint It On or Shrink Wrap • Electrospinlacing provides seamless MCP layer. – Multi-filament fiber projected via electric charge onto grounded surface – Greatly improved tactile feedback – Custom, form fit – Seamless integration of wearable computing
• Melt Blowing – Blowing liquefied polymer onto surfaces
• Melt Spinning – MIT colleague ChemE and Institute for Soldier Nanotechnology (ISN) (MOU: Natick National Protection Center)
Design by Nature
Apply biomimetics to Bio-Suit: Imitate nature’s design Remarkable adaptations to gravity Giraffes (>5 m, 1900 kg) and Snakes
Giraffe’s challenge: hydrostatic pressure gradient imposes 400 mmHg pressure difference in head between ground level and tree level
Giraffe’s solution: neck skin provides pressurization to assist the blood vessels with transport, compensating for the enormous pressure differences between heart and head (Hargens et al., 1987 and Wood et al., 1992)
Energy Harvesting • Harvest from the environment: – Thin films enable integrated heat pump capabilities (Hodgson 2003) – Photovoltaics convert solar energy into electric charge for suit (Hodgson 2003)
• Harvest from the body: – Piezo Energy Generator (PEG) Module converts mechanical strain into electric charge (MIDÉ 2003)
• Current efficiency levels are not sufficient for any of these materials
Visualizations
Transparent Exploration, Tx • A piece of space wrapped around the body Vacuum Cuff, B. Pitts, 2003
Development Approach Model regular cross sections and move towards irregular PVC pipe is cylindrical and static Calf has high degree of irregularity and is four dimensional
Create even pressure distribution around non-bending regions before attempting joints Attempt calf and thigh before the knee, a ~one DOF joint
Pressure Measurements
Results for Cylinder
MCP Concept Construction
Experimental Verification
Pressure Verification
Concept: Lines of Nonextension (LoNE) High E d 1. Circle drawn on skin 2. Skin stretches as body moves Low E 3. The circle deforms to become an ellipse, revealing lines of nonextension = Minimum Strain Adapted from A.S. Iberall 1970
Note: In some areas of the body the skin stretches in all directions, therefore there are no local lines of nonextension.
Systems Approach
EVA Systems Engineering Approach Exploration Systems must work in many different environments ßThermal: ßLunar Day - active cooling (Apollo heritage) ßLunar Night - active heating (EMU gloves) Why carry around both systems all the time when each thermal environment lasts two weeks? ßImpact: ßRiding in a vehicle or working at a digging site, can use parasol-like Whipple shield (like sunshades in the desert.) ßDon’t need bulk and weight of shielding inside a cave! ßPressurization: ßLook at pressurization as one of many EVA subsystems ßMinimizing the size of the pressure system outer envelope maximizes the flexibility for decoupling other systems. ßMotivation for MCP, along with maneuverability and safety
Systems Approach (cont.) Example (Pressurization): Junction to Torso Thigh
Leg
Non-moving Parts Moving Parts (joints)
Calf Knee Ankle
Pressure production for non-moving parts potentially different from flexing joints. Boot is a separate system. (Member of team worked for Reebok.)
Need to develop subsystem junctions (interface problem).
Plans for Cost Analysis • Actual Bio-Suit system to be developed is too far in the future for useful bottom-up cost analysis • Look at current EVA System: analyze according to areas where new Bio-Suit Systems can impact total utilization costs •Inspection •Maintenance •Reparability •Safety (# of backups) •Flexibility •Extensibility •Ability to incorporate new technology (continuous upgradeability) •Training (ease and intuitiveness of use)
• Analyze current systems cost: NASA cooperation • Would be useful to get insight into NASA and contractor analyses of the costs of future suit designs
Future Exploration • Bio-Suit MCP feasibility – – – –
Materials Design Mission Planning Wearable computing/analysis
• Exploration Systems – Flexibility, Design Lifetime, Servicing
• Human Modeling – – – –
Locomotion Space Suit Metabolic Cost Individual skin suit to astro./dig. model
• Performance Augmentation – Pathologies, Rehabilitation – Traverse Planning – Robotics/Human
• Design by Nature
References Annis, J.F., and Webb, P., “Development of a Space Activity Suit,” NASA Contractor Report CR-1892, Webb Associates, Yellow Springs, Ohio, 1971. Carr, C.E., Hodges, K.V. Hodges, Newman, D.J., “Geologic Traverse Planning for Planetary EVA”, AIAA and SAE International Conference on Environmental Systems (ICES 2003), Vancouver , B.C., Canada, July 2003. Clapp, W., “Design and Testing of an Advanced Spacesuit Glove,” Massachusetts Institute of Technology, Cambridge, MA, 1983. Compton, R.R., Geology in the Field, John Wiley and Sons, New York, New York, 1985. Connors, Mary M., Eppler, Dean B., and Morrow, Daniel G., Interviews with the Apollo Lunar Surface Astronauts in Support of Planning for EVA Systems Design, Ames Research Center, National Aeronautics and Space Administration, 1994. Frazer, A. L., Pitts, B. M., Schmidt, P. B., Hoffman, J. A. and Newman, D. J., “Astronaut Performance: Implications for Future Spacesuit Design”, 53rd International Astronautical Congress, Paper No. IAC-02-6.5.03, Houston,TX, October 2002. Hodgson, E. “Chameleon Suit”, NIAC Phase II, 2003. Iberall, A.S., “Development of a Full Pressure Altitude Suit,” WADC Technical Report 58-236, Wright Air Development Center, Wright-Patterson Air Force Base, Ohio, June 1958. Iberall, A.S., “The Experimental Design of a Mobile Pressure Suit,” Journal of Basic Engineering, June 1970. pp. 251-264 Iberall, A.S., “The Use of Lines of Nonextension to Improve Mobility in Full-Pressure Suits,” AMRL-TR-64-118. Aerospace Medical Research Laboratories, WrightPatterson Air Force Base, Ohio 1964. Jones, E.M., Apollo Lunar Surface Journal, http://www.hq.nasa.gov/office/pao/History/alsj/frame.html. Kieffer, H.H., Jakosky, B.M., Snyder, C.W., Matthews, M.S. (editors), Mars, University of Arizona Press, Tucson, Arizona, 1992. Kosloski, L., US Space Gear: Outfitting the Astronaut, Smithsonian Institute Press, Washington, DC, 1994 Kosmo, Joseph, and Ross, Amy, Results and Findings of the Representative Planetary Surface EVA Deployment Task Activities, Flagstaff, Arizona (CTSD-ADV-470), National Aeronautics and Space Administration, Crew and Thermal Systems Division, Lyndon B. Johnson Space Center, Houston, Texas, 2000. Madden, Peter G., Polyprole actuators: modeling and performance, MIT, March 2001 Midé Technologies, Piezoelectric and SMA expert consultants. Newman, D.J., “Life in Extreme Environments: How Will Humans Perform on Mars?” ASGSB Gravitational and Space Biology Bulletin, 13(2): 35-47, June 2000. Pitts, B., Brensinger, C., Saleh, J., Carr, C., Schmidt, P., Newman, D., “Astronaut Bio-Suit for Exploration Class Missions,” NIAC Phase I Final Report, Cambridge, Massachusetts Institute of Technology, 2001. Saleh, J.H., Hastings, D.E., and D.J. Newman, "Flexibility in System Design and Implications for Aerospace Systems," Acta Astronautica, (accepted, in press) 2003. Saleh, J.H., Hastings, D.E., and D.J. Newman, "Weaving Time into System Architecture: Satellite Cost per Operational Day and Optimal Design Lifetime," Acta Astronautica, (accepted, in press) 2003. Santee, W.R., Allison W.F., Blanchard, L.A, and Small, M.G., “A Proposed Model for Load Carriage on Sloped Terrain”, Aviation, Space, and Environmental Medicine, Vol. 72, No. 6, June 2001. Schmidt, P., “An Investigation of Space Suit Mobility with Applications to EVA Operations,” Doctoral Thesis, Massachusetts Institute of Technology, Cambridge, MA, 2001. Stone, R.W., Man’s Motor Performance Including Acquisition of Adaptation Effects in Reduced Gravity Environments, National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1974. Trotti and Associates, Inc., Extreme environment design consultants. Webb, Paul, and Annis, J.F., “The Principle of the Space Activity Suit,” NASA Contractor Report CR-973, Webb Associates, Yellow Springs, Ohio, 1967. Webb, Paul, “The Space Activity Suit: An Elastic Leotard for Extravehicular Activity,” Aerospace Medicine, April 1968. pp. 376-383. Workshop notes from Science and the Human Exploration of Mars, Goddard Space Flight Center, January 11-12, 2001. URLs: Aspen Systems http://www.aspensystems.com, Natick Soldier Center http://www.sbccom.army.mil/products/cie/Electrospinlacing.htm
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