Evaluating Human-EVA Suit Injury Using
Wearable SensorsMASS
by
Ensign Sabrina Reyes, U.S. Navy
B.S., Aerospace EngineeringUnited States Naval Academy (2014)
Submitted to the Department of Aeronautics and Astronauticsin partial fulfillment of the requirements for the degree of
Master of Science in Aeronautics and Astronautics
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
ACUS0 ILNSTITUTE)F TECHNOLOGY
JUN 28 2016
IBRARIESARCHIVES
June 2016
@ Massachusetts Institute of Technology 2016.
A uthor ...............
Certified by..
All rights reserved.
Signature redacted;.......
Department of Aeronauticand Astronautics
V~ \ %, \May 19, 2016
Signature redacted--. ...........
Jelfrey A. Hoffman, Ph.D.Professor of theractice, Aeronautics and Astronautics
Siqnature redactedA ccepted by .................. I........ ..............................
PauloI C Lozno7n PhDT
Associate Professor of Aeronautics and AstronauticsChair, Graduate Program Committee
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2
Evaluating Human-EVA Suit Injury Using Wearable Sensors
by
Ensign Sabrina Reyes, U.S. Navy
Submitted to the Department of Aeronautics and Astronauticson May 19, 2016, in partial fulfillment of the
requirements for the degree ofMaster of Science in Aeronautics and Astronautics
Abstract
All the current flown spacesuits are gas pressurized and require astronauts to exert asubstantial amount of energy in order to move the suit into a desired position. Thepressurization of the suit therefore limits human mobility, causes discomfort, andleads to a variety of contact and strain injuries. While suit-related injuries have beenobserved for many years and some basic countermeasures have been implemented,there is still a lack of understanding of how humans move within the spacesuit. Therise of wearable technologies is changing the paradigm of biomechanics and allowinga continuous monitoring of motion performance in fields like athletics or medical re-habilitation. Similarly, pressure sensors allow a sensing capability to better locatethe areas and magnitudes of contact between the human and their interface and re-duce the risk of injuries. Coupled together these sensors allow a better understandingof the complex interactions between the astronaut and his suit, enhance astronautsperformance through a real time monitoring and reducing the risk of injury. Thefirst set of objectives of this research are: to gain a greater understanding of thishuman-spacesuit interaction and potential for injury by analyzing the suit-inducedpressures against the body, to determine the validity of the particular sensors usedwith suggested alternatives, and to extend the wearable technology application toother relatable fields such as soldier armor and protective gear. An experiment wasconducted in conjunction with David Clark Incorporated Company on the LaunchEntry Development spacesuit analyzing the human-spacesuit system behavior for iso-lated and functional upper body movement tasks: elbow flexion/extension, shoulderflexion/extension, shoulder abduction/adduction and cross body reach, which is acomplex succession of critical motions for astronaut and pilot task. The contact pres-sure between the person and the spacesuit was measured by three low-pressure sen-sors (the Polipo) over the arm, and one high-pressure sensor located on the shoulder(Novel). The same sensors were used in a separate experiment conducted in con-junction with Protect the Force Company on several different United States MarineCorps (USMC) protective gear configurations, which analyzed the human-gear in-teractions for: shoulder flexion/extension, horizontal shoulder abduction/adduction,vertical shoulder abduction/adduction, and the cross body reach. Findings suggest
3
that as suit pressurization increases, contact pressure across the top of the shoulderincreases for all motion types. While it proved to be a perfectly acceptable methodfor gathering shoulder data, improvements can be made on the particular sensorsused and the type of data collected and analyzed. In the future, human-suit interfacedata can be utilized to influence future gas-pressurized spacesuit design. Addition-ally, this thesis briefly explores the incompatibilities between Russian and U.S. EVAcapabilities in order to make a case for equipment standardization.
Thesis Supervisor: Jeffrey A. Hoffman, Ph.D.Title: Professor of the Practice, Aeronautics and Astronautics
4
Acknowledgments
First and foremost, I would like to thank the wonderful advisors I had at MIT, without
whom this thesis could have never happened. To Dr. Jeff Hoffman, thank you for
all your honest guidance during the thesis process and regarding my aspirations to
become an astronaut. To Dr. Dava Newman, thank you for introducing me to
the world of human spaceflight and reigniting my passion for aerospace. My MIT
experience would not have been the same without such a wonderful person in my life
to give me incredible opportunities like meeting Buzz Aldrin, skiing in Montana for
a conference, or working with spacesuits and other fantastic people for my research.
Thank you both for all the opportunities and the unwavering support.
To the EVA team, Pierre, Alexandra, and Allie, I cannot thank you enough for all
your help on this thesis. It seriously would not have happened without you. Thanks
for all the fun meetings, for being some of my first friends at MIT, and for being
incredibly patient and helpful with all my questions even after you had moved on to
bigger and better things!
To Tony, John, and Grant, thank you guys for being my Navy partners in crime.
You guys understand and tolerate my awful mood swings, humor, and personality
probably more than anybody else, and for that I am so grateful. I am happy I had you
all to provide advice and/or sounding boards for weird Navy situations like P-codes,
disappearing without leave, etc. Tony and Grant, I guess I'm sort of happy we will
all be in the same pipeline so I can see your ugly faces even after we leave MIT, and
John, I am going to miss you so much but I know that you'll kick butt in flight school!
To Hannah, thanks for being the sweetest roommate, officemate, classmate, etc.
Our weird cookie binges, burger quests, lunch runs, and wonderful conversations kept
me from insanity (seriously). Thank you for being such a wonderful and patient
friend.
To Conor, Richard, Lynn, Forrest, Eddie, and the rest of the MVLers, you guys
are seriously the most amazing people ever! I am highly convinced that the Man
Vehicle Lab is the coolest, funnest lab at MIT, plus we produce some darn good
5
research. Thanks for letting me waste all your time because I don't feel like doing
any of my own work. Thanks for lab lunches, lab dog-sitting adventures, IEEE skiing,
HST formal shenanigans, Captain America movie nights, and all the other incredible
memories that I will cherish forever. I will miss you all so much, please come visit
me wherever I am in the Navy!
To the close friendships: Macauley, Anne, Parker, Patricia, Mark, and Emily,
thank you guys for random dinners, drink nights, and for distracting each other from
research and life. I love you guys to the moon and back.
A special thanks to Liz Zotos, Barb DeLaBarre, Ed Ballo, and Beth Marois for
providing advice, help, and friendship throughout my stay at MIT.
Finally, I would like to thank my family for their incredible prayers, love, support,
and encouragement. To Elizabeth, thank you for adopting my family into your own,
because you have become such an important part of our family. Thank you for all
your spot-on advice in all areas of life, because no one else seems to understand my
way of thinking quite like you do. I love all of you very much and would not have
gotten to where I am without you.
6
Contents
1 Introduction
2 Literature Review
2.1 Extravehicular Activity . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 EVA Training and Injury . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Previous Work on Development of a Quantitative Understanding of
Human-Spacesuit Interaction . . . . . . . . . . . . . . . . . . . . . . .
3 Sensor Systems and Experimental Design
3.1 Sensor System s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.1 Low Pressure Sensing System, the "Polipo" . . . . . . . . . ..
3.1.2 Novel High-Pressure Shoulder Sensor . . . . . . . . . . . . . .
3.1.3 APDM Inertial Measurment Units . . . . . . . . . . . . . . . .
3.2 Spacesuit Testing Experimental Design . . . . . . . . . . . . . . . . .
3.3 Marine Protective Gear Experimental Design . . . . . . . . . . . . . .
4 Novel System Results and Discussion
4.1 David Clark Experiment . . . . . . . . . . . .. . . . . .
4.1.1 Pressure Distributions . . . . . . . . . . . . . .
4.1.2 Pressure Profiles . . . . . . . . . . . . . . . . .
4.1.3 Statistical Analysis . . . . . . . . . . . . . . . .
4.2 Protect the Force Armor Gear Prototype Experiments
4.3 Conclusions and Future Work . . . . . . . . . . . . . .
7
13
16
16
19
23
25
25
25
28
29
30
32
36
. . . . . 36
. . . . . 37
. . . . . 41
. . . . . 47
. . . . . 53
. . . . . 55
5 International EVA Capabilities 58
5.1 A Case for EVA Standardization . . . . . . . . . . . . . . . . . . . . 58
6 Conclusions 66
A Human-Suit Interface Pressure Evaluation 68
8
List of Figures
2-1 Extravehicular Mobility Unit and Exploded View Diagram. (Image
Sources: NASA, Hamilton Sustrand) . . . . . . . . . . . . . . . . . . 17
2-2 Pivoted HUT on left and Planar HUT on right. Note the different
angles of the scye bearings in the two HUTs. (Image Source: NASA) 18
2-3 David Clark Launch and Entry Development Suit . . . . . . . . . . . 18
2-4 Astronaut training in the NBL in an inverted position (Image Source:
N A SA ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3-1 Printed carbon-grease sensor with electrode extensions. (Image Source:
W yss at Harvard, 2014) . . . . . . . . . . . . . . . . . . . . . . . . . 27
3-2 AMOHR two-stranded conductive tape used for second Polipo iteration. 28
3-3 Experimental Sensor Systems: A) Low-pressure Polipo sensors, B)
High-pressure Novel shoulder sensor, C) APDM Opal inertial mea-
surement unit. (Image Source: Anderson, 2014) . . . . . . . . . . . . 29
3-4 Placement of the in-suit sensor systems. (Image Source: Anderson, 2014) 30
3-5 Descriptions of the four upper body motions performed during the
spacesuit experiment: three isolated joint motions (elbow flexion/extension,
shoulder flexion/extension, shoulder abduction/adduction), and one
functional task (cross body reach). (Image Source: Anderson, 2014,
Hilbert et al. 2014) . . . . . . . . . . . . . . . . . . . . . . . . . . ..31
9
3-6 Experimental Design Test Protocol: Each movement group consists
of a counterbalanced ordering of the motions. The motions studied
were: three isolated joint motions (elbow flexion/extension, shoulder
flexion/extension, and shoulder abduction/adduction) and a functional
task motion (cross body reach). In each movement group, the specific
motion was repeated 5 times for a total of 15 repetitions per motion. 32
3-7 Different USMC protection gear configurations used during testing . 33
3-8 Horizontal shoulder abduction/adduction. Beginning with their arms
extended at shoulder height, shoulder width apart, the subject bends
their arms at the shoulder in the transverse plane. The subject moves
through his or her maximum range of motion. The subject returns to
the initial start position then releases to the relaxed position. . . . . . 34
3-9 Protective Gear Experimental Design Test Protocol. Each movement
group consists of a counterbalanced ordering of the motions. The mo-
tions were: three isolated joint motions (shoulder flexion/extension,
shoulder abduction/adduction vertical, shoulder abduction/adduction
horizontal) and a functional task motion (cross body reach). In each
movement group, the specific motion was repeated 5 times for a total
of 15 repetitions per motion. . . . . . . . . . . . . . . . . . . . . . . . 35
4-1 Orientation of the Novel Sensor. The orientation corresponds to the
information in each pressure distribution figure. Coloring is for orien-
tation and is not related to pressure scales. (Image Source: Hilbert
20 15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7
4-2 Contact pressure distributions for each motion at each pressurized con-
dition for Subject 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4-3 Contact pressure distributions for each motion at each pressurized con-
dition for Subject 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4-4 Contact pressure profiles for all motions in the 2.5-psi pressurized con-
dition for Subject 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
10
4-5 Contact pressure profiles for all motions in the 3.5-psi pressurized con-
dition for Subject 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4-6 Contact pressure profiles for all motions in the 2.5-psi pressurized con-
dition for Subject 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4-7 Contact pressure profiles for all motions in the 3.5-psi pressurized con-
dition for Subject 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4-8 Effects of pressurization on mean contact pressure for Subject 1. . . . 49
4-9 Effects of pressurization on mean contact pressure for Subject 2. . . . 49
4-10 Effects of motion type on mean contact pressure for Subject 1. . . . . 50
4-11 Effects of motion type on mean contact pressure for Subject 2. . . . . 50
4-12 Effect of subject on mean contact pressure for intermediate pressuriza-
tio n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1
4-13 Effect of subject on mean contact pressure for full pressurization. . . 51
4-14 Pressure distributions of all motions for different USMC armor config-
urations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4-15 Pressure distributions for rifle carry motion for Configuration 1 (on
left) and Configuration 4 (on right). . . . . . . . . . . . . . . . . . . . 55
4-16 Novel Single S2012 Sensor with 2 cm diameter (Image Source: novel.de) 57
5-1 Rear entry opening for Russian Orlan-M spacsuit. (Image Source:
NASA)........ ................................... 59
5-2 The U.S. EMU and Russian Orlan-M spacesuit shown side by side.
(Image Source: NASA) . . . . . . . . . . . . . . . . . . . . . . . . . . 63
11
List of Tables
3.1 Anthropometrics from typical Marine compared to anthropometrics of
subject used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
12
Chapter 1
Introduction
Human spaceflight programs are facing new challenges rising from the evolution of the
exploration agenda, the need for Commercial Crew and the new entry on the market
of space tourism. These different activities bring new challenges: planetary explo-
ration missions will require intensive extravehicular activities (EVA), space tourism
will require new, cheap and user friendly space systems, specifically, pressure suits.
Spacesuits need to adapt to this new era of space exploration and democratization
of space. Spacesuits are technical marvels: their main functions are providing oxy-
gen, pressure, food, water, waste removal, communication, thermal control, mobility,
radiation protection, direct sunlight protection, and micrometeorite protection. The
human body cannot survive in the vacuum of space because all air the air would
rush out of the lungs, blood vessels would rupture and the blood would eventually
boil. However, lower total pressure than atmospheric pressure can keep the astro-
naut alive and be an adequate environment to work in as long as the partial pressure
of oxygen is maintained. One of the most important functions of a spacesuit is to
provide mobility: "the advantage of a human in space over a robot is the ability to
see, touch, and adapt instantly to real-time conditions. This is an advantage only if
the astronauts are able to effectively use their hands, arms, legs, eyes, and brains."
Spacesuit joints are one of the most critical parts of the design of the spacesuit since
they determine its mobility. The common gas-pressurized spacesuit designs tend to
keep a constant or near constant volume in the joints. Spacesuits have evolved since
13
the initial designs but many issues remain. Over time, these gas-pressurized suits
cause fatigue, increase metabolic expenditure, and eventually may lead to injuries
in astronauts. Gas-pressurized suits cause astronauts to experience discomfort, hot
spots, skin irritation, abrasions, contusions, and over time injuries requiring medical
attention [21]. Injuries occur primarily where the person impacts and rubs against
the suit to change its position. Although most injuries have been minor and did not
affect mission success, injury incidence during EVA is much higher than injury that
occurs elsewhere on-orbit. While the most common injuries occur in the hands, feet,
and shoulders, shoulder injuries (including rotator cuff tears that require surgery)
are some of the most serious and debilitating injuries astronauts face as a result of
working in the suit. Countermeasures have been developed to mitigate suit-related
injuries, but still relatively little is known of how humans move within the spacesuit.
In addition to the technical challenges, human spaceflight programs face implementa-
tion challenges in terms of cost, schedule, and regulatory barriers. In order to provide
a holistic view of the problems presented in human spaceflight, we must look at both
the technological and policy aspects. For the purpose of this thesis, we will look
specifically at international cooperation for EVA capabilities.
The objectives of this research are to:
1. gain a greater understanding of the human-spacesuit interaction specifically at
the shoulder interface in order to determine potential for injury by analyzing
the suit-induced pressures against the body using a network of pressure-sensing
and kinematics systems,
2. determine the validity of the particular sensors used in an effort to understand
this interaction and suggest alternatives if the current sensors are found to be
sub-optimal,
3. extend the wearable technology application to other relatable fields such as
soldier armor and protective gear,
4. and finally, compare and contrast EVA capabilities and incompatibilities be-
14
tween the U.S. and Russia in order to build a case for equipment standardiza-
tion.
Chapter 2 provides relevant literature on EVA training, astronaut injury, shoulder
injury, and previous studies and countermeasures addressing these issues.
Chapter 3 sets forth the pressure sensing systems and experimental design that
were used in order to conduct experiments with the David Clark Company for space-
suits and Protect the Force Company for United States Marine Corps (USMC) pro-
tective gear.
Chapter 4 presents the results and discussion of the shoulder pressure data that
was gathered during the human subjects experiment for the spacesuits and protective
gear. A combination of graphical and statistical analyses were performed to examine
the data, and results regarding pressure distributions, pressure profiles, and effect of
pressure magnitudes are presented.
Chapter 5 presents a general comparison of EVA capabilities between the U.S.
and Russia in order to build a case for equipment standardization.
Finally, Chapter 6 provides a summary and conclusion of all the results of the
thesis. Recommendations for future work are also provided.
15
Chapter 2
Literature Review
The following is a review of literature on space suit design and EVA working envi-
ronments.
2.1 Extravehicular Activity
Extravehicular activity (EVA) is critical to human spaceflight. Since the Soviet cos-
monaut Alexey Leonov performed the first EVA on March 18, 1965, to the moment
American astronaut Neil Armstrong stepped foot on the moon on July 20, 1969, the
human race has been eager to further human space exploration for national pride, the
sake of curiosity and possibly survival, as well as secondary rationales that include
economic development, new technologies/innovation, education and inspiration, and
the development of peaceful international relations. Astronauts and cosmonauts have
performed nearly 300 EVAs as of 2009 [6]. Only 14 of those EVAs have been con-
ducted on the lunar surface in one-sixth gravity. However, despite the large number
of EVA expeditions over the course of forty years, relatively little is known about
the interactions between the human and the EVA suit that they utilize. NASA has
already publicly expressed its intentions for human missions to Mars, but before these
missions can be realized, it is imperative that we can thoroughly characterize space
suit performance. This research addresses how we are currently developing a method
to evaluate space suit design and understand injury.
16
Figure 2-1: Extravehicular Mobility Unit and Exploded View Diagram. (ImageSources: NASA. Hamilton Sustrand)
The fundamental challenges faced by U.S. space suit designers include providing
pressure. oxygen, waste removal. coimunication. food, water, therimal control, 111o-
bility. radiation protection, and a safe working environment [20]. U.S. astronauts
currently fly and train in the extravehicular mobility unit (EMU). The EMU consists
of the space suit assembly (SSA), protective and comfort pieces. and the life support
system. The space suit assembly is a 14-layer suit weighing 64 kg (140 lb) that is
pressurized to 29.6 kPa (4.3 psi) [12]. The additional portable life support systeim
(PLSS) backpack increases the total suit weight to 115 kg (254 ib). Components of
the SSA are available in multiple standard sizes to allow astronauts to mix pieces
and provide a better fit. Although suit fit is optimized for each astronaut with the
standard sizes available, not all astroamtsanthropometries cai be comfortably ac-
conmnmodated. Currently, the only component of the SSA that can be custom fit for
an astronatutspecific anthropometric measurements are the gloves. The hard upper
torso (HUT), a fiberglass shell that connects to the arm, helnet. and lower torso
asseniblies. coies in two designs: the pivoted and planar HUT. There are only three
sizes currently available to astronauts: nedimun, large, and extra large [9]. Both are
available for use during training. bitt only the planar HUT is currently used iII space-
flight. The pivoted HUT is no longer used on orbit simnce a rupture in the bellows
would be a catastrophic failure of suit integrity [21]. The planar HUT has planar
17
seve bearings in fixed planes at the armli openings, vhereas the 1)ivoted HUT has a
shoulder gimbal with a two-point pivot to aid the range of motion of the shoulder
joilit [19].
Figure 2-2: Pivoted HUT on left, and Planar HUT on right. Note the different angles
of tlie seve bearings in the two HUTs. (Image Source: NASA)
There are several prototylpe suits that have been developed for planetary aild deep
space exploration. Future nissions to \Jars will require spacesuits that have high
mobility and dexterity. and currentlv the ENJU does not satisfy those requirements.
The E\IU limits mobility and requires a substantial aniount of eiiergy iii order to
move the suit into a desired position. Mechanical counter-pressure suits such as
the BioSiit are currently bei]ig developed to address issues of mobility and energy
consmiiption. but gas-pressurized suits are officially NASA's state of the art capability
[13]. Of the gas pressurized space suits being developed to address different sceliarlo
requirements. the one of particular focus in this thesis is the David Clark Launch and
Entry Development Suit. which is currently being developed to address launch and
entry requirements. No other information is currently publicly available for this suit.
Figure 2-3: David Clark Launch and Entry Development Suit
18
2.2 EVA Training and Injury
Extravehicular activity training currently focuses on preparing only for microgravity
as astronauts are only sent to the International Space Station (ISS). The Neutral
Buoyancy Laboratory (NBL), a 23.5 million liter pool at the NASA Johnson Space
Center, is the primary facility that conducts training for the weightless micrograv-
ity environment; it contains a full-size mock-up of the International Space Station.
Every astronaut spends an average of 11.6 hours of training in the NBL per hour of
planned in-flight EVA and between 200-400 hours in training over the course of their
career [19, 3]. The specific number of hours per astronaut depends on their mission's
specific sorties, and the technical details of the EVA. NASA defined an optimum
work envelope for tasks performed on the Hubble Space Telescope and ISS, however,
repeatedly performing tasks outside the envelope can have a significant impact on the
astronaut [9]. As mentioned previously, the current EMU is pressurized at 4.3 psi,
which makes it difficult to move within the spacesuit. Maintaining different postures
to complete certain tasks within the suit causes increased metabolic expenditure and
fatigue. A combination of the time spent training for each EVA and the EVA suit
mechanics is cited as a contributing factor for the astronaut injury incidence rate
[19, 18]. Gravity acting on the astronaut inside the neutrally buoyant space suit
causes shifting within the suit in the NBL not seen on orbit [3]. Another important
aspect in NBL training is that crews are subjected to inversion for short durations,
where the body is oriented in a head down position greater than 45 degrees as seen in
Figure 2-4 [9]. Inversion is defined as a position in which the body is at a head-down
angle of more than 45 degrees; this position loads the shoulders with the astronaut's
full body weight during training for a few minutes at a time. This commonly leads to
injury and discomfort. The lack of restraint within the suit has resulted in a shoulder
bruising during training for nearly every case. Additionally, insufficient recovery time
between NBL training runs prevents astronauts from physically recovering and may
exacerbate developing injuries [9]. Although no EVA-related injury has prevented
successful completion of a mission objective, there have been several instances when
19
the EVA was nearly terminated(l due to suit discomfort [18 3].
lollA
Figure 2-4:
NASA)Astronaut training in the NBL in an inverted position (hage Source:
Wieii sunt discomfort becomes suit-related injury. it becomes a major cause for
concern. Anecdotal reports from astroiiauts have mentioned the occurreice of in-flight
inisculoskeletal injuries since the begiining of NASA's human spaceflight progran
[18]. In December 2002. Williams and Johnson at NASA created the shoulder injury
tiger team to evaluate the possible relationship between shoulder injuries and EVA
training in the NBL. The Tiger Team confirmed that NBL EVA training was directly
liked to a number of shoulder injuries [9]. By administering aii EMU Shoulder
Injury Survey to 42 astronauts aund astronaut candidates. they were able to find the
primary factors coitributing to both major. defined as significant shoulder injuries
requiring medical intervention or surgical correction. and i inor. defined as self-limited
conditions requiring iiiinimal medical intervention, injuries. They foun11d that factors
contributing to both major andi minor injuries are: limitations to niormal shoulder
mobility iin the E\IU Planar HUT. performing tasks ini inverted body positions. using
heavy tools. and frequent NBL runs. Three astronauts had surgery for EVA training-
related shoulder ilIjuries. only one of which had sustained a shoulder injury previously.
Additionally. the onset of a moderate dull ache over the top of the shoulder or within
20
I
the shoulder joint during or within 24 hours of an NBL run strongly suggests a causal
relationship, and repeated episodes of pain during training suggest overuse that could
lead to surgical repair [21, 9]. The findings and recommendations of the tiger team are
wide-ranging due to the multi-factorial nature of EVA training injuries [21]. Based on
their findings, Williams and Johnson made key recommendations to mitigate injury,
but these recommendations were only based on subjective findings [9].
From 2002 to 2004, Strauss et al. quantified and characterized signs, symptoms,
and injuries resulting from extravehicular activity spacesuit training at NASA's Neu-
tral Buoyancy Laboratory immersion facility. By identifying the frequency and inci-
dence of symptoms by location and mechanism, they determined the most frequent
injuries occurred in the hands and shoulders, with shoulders being rated the most
severe injuries. Of 770 spacesuit symptom questionnaires, 24.6% of tests yielded
symptoms, with 47.6% of symptoms in the hands, 20.7% in the shoulders, and 11.4%
in the feet. The only shoulder countermeasures available are supplementary com-
fort pads, an EMU shoulder harness to prevent shoulder contact complaints and an
optimal suit fit to include unique fit adjustments [19].
In 2007, Scheuring published his results from the Apollo Medical Operations
Project. The Apollo Medical Operations Project collected feedback from 14 of the 22
surviving Apollo astronauts. Recommendations centered on improving the function-
ality of the suit as well as improving human factors and safety features. Of the EVA
Suit recommendations listed, the recommendations related to mitigating astronaut
injury were to improve glove flexibility, dexterity, fit, and to increase general mobil-
ity by a factor of four [17]. The astronauts surveyed also recommended increasing
ambulatory and functional capability through increased suit flexibility, decreased suit
mass, lower center of gravity, and reduced internal pressure [17]. In 2009, Scheuring's
following study cataloged and analyzed all in-flight musculoskeletal injuries occurring
throughout the U.S. space program beginning with the Mercury program through
the conclusion of ISS Expedition 13 in September 2006 [18]. A total of 219 in-flight
musculoskeletal injuries were identified, 198 occurring in men and 21 in women. The
incidence of in-flight musculoskeletal injuries was found to be 0.021 injuries per day
21
for male crewmembers and 0.015 injuries per day for female crewmembers. While
hand injuries represented the most common location of injuries, shoulder and back
injuries are also notable in the data of injuries separated by anatomical location. The
most common types of injury were abrasions, contusions, strains, and lacerations. Of
note, most astronauts also remarked that their wounds healed more slowly while on
orbit. Hand injuries were most common among EVA crewmembers, often due to the
increased force needed to move pressurized, stiff gloves. These hand injuries mani-
fested themselves as small blisters and pain across their metacarpophalangeal (MCP)
joints. Injuries occurred most frequently during crew activity and within the EVA
suit. Engineers can use in-flight injury data to further refine the EVA suit and vehicle
components [18]. In 2010, Opperman developed a musculoskeletal modeling tool to
compare various spacesuit hard upper torso designs and focus on optimizing comfort
and range of the motion of the shoulder joint within the suit. He also performed a
statistical analysis to investigate the correlations between the anthropometrics of the
hand and susceptibility to injury using a database of 192 male crew members' injury
records. He found hand circumference and width of the MCP joint to be significantly
associated with injuries. Experimental testing was also conducted to characterize
skin blood flow and contact pressure inside the glove. The tests show that finger
skin blood flow is significantly altered by contact force/pressure, and that occlusion
is more sensitive when it is applied to the finger pad than the finger tip [16].
Countermeasures to address shoulder injury in the NBL and orbit include different
types of simple padding and harnesses for the HUT. The most commonly used pads
are primarily for protection from the scye bearing and HUT shell, while the rarely
used shoulder harness acts like a pair of suspenders inside the HUT that have a pad
assembly at the shoulders to absorb contact loads in the suit [21]. Countermeasures
can still be improved by expanding our understanding of human-spacesuit interaction.
22
2.3 Previous Work on Development of a Quanti-
tative Understanding of Human-Spacesuit In-
teraction
Over the past few years, a team of researchers at the Massachusetts Institute of Tech-
nology (MIT) along with collaborators at Trotti and Associates, Inc. (Cambridge,
MA), has studied Spacesuit Trauma Countermeasure System for Intravehicular and
Extravehicular Activities under NASA Grant NNX12AC09G. The main objectives
were to: 1) analyze data for correlations between anthropometry, space suit com-
ponents, and injury, 2) model human-spacesuit interaction, 3) design and develop
modular protective devices to mitigate injury, and 4) quantify and evaluate human-
spacesuit interaction using a suite of sensors [14].
The first objective was addressed by a study published in 2014. The study quan-
titatively evaluated the causes of astronaut shoulder injury and performed a meta-
analysis investigating injury trends, proposing an injury classification system, and
creating predictive statistical shoulder injury models using a database of 278 astro-
nauts that included anthropometric measurements, training record, and injury record
[3, 2]. It found that percent of training performed in the planar HUT was the strongest
predictor variable for injury, while training frequency and recovery between sessions
were also important variables. It also identified that bideltoid breadth, expanded
chest depth, and shoulder circumference were the most relevant anthropometric mea-
surements for predicting injury. The second objective was addressed by Diaz at the
IEEE Aerospace Conference in 2014, where a biomechanical analysis using OpenSim
(Stanford, CA) was performed to understand the effect of the space suit on muscle
activation and force generation on the knee using motion capture data and EMU
joint torque data [5]. The third objective was addressed by developing injury pro-
tection concepts, evaluating materials for their offloading capabilities, and eventually
developing both passive and inflatable protective device prototypes. The fourth and
final objective of evaluating human-spacesuit interaction has been addressed, but
23
methods and tools are continually being improved. A human subjects experiment
was performed at David Clark Company and at NASA Johnson Space Center using
the David Clark Mobility Suit and the NASA developmental Mark III suit. A pres-
sure sensing system was built to evaluate pressures over the arm for this experiment,
and the results on sensor performance are analyzed and discussed [3]. An additional
commercially produced pressure sensor measured pressures at the shoulder for this
experiment, and a quantitative analysis of the human-suit interaction at the shoul-
der was published [8]. The two pressure sensing systems were used in conjunction
with kinematic inertial measurement units, and the kinematics data has also been
published [4].
The quantitative techniques used in this thesis and in the preceding research
present a novel way to understand human-spacesuit interaction. Prior to this grant,
studies only included cataloging incidence and mechanisms of injury, but none had
assessed the human-suit interface with experimental methods. The implications of
this research will help to influence suit techniques and future spacesuit design.
24
Chapter 3
Sensor Systems and Experimental
Design
Through prior work on characterizing the human-suit interface, it was determined
that the following suite of pressure-sensing systems and inertial measurement units
were to be used [3, 8].
3.1 Sensor Systems
3.1.1 Low Pressure Sensing System, the "Polipo"
A custom-built, low-pressure sensing system was designed for placement along the arm
for 5-60 kPa pressure ranges [3]. These sensors were created at the Massachusetts
Institute of Technology in conjunction with researchers at the Wyss Institute for
Biologically Inspired Engineering at Harvard. Known as the Polipo, this low pressure-
sensing system uses 12 soft hyper-elastic sensors to measure low-pressures applied to
the body under soft goods. The sensors are cast from a silicon rubber (EcoFlex0030,
Smooth-On, Inc., Easton, PA), and after two individual pieces are mated, they are
injected with a highly conductive liquid metal called galinstan (Gallium-Indium Tin
eutectic, 14364, Alfa Aesar, Ward Hill, MA), in a spiral pattern to minimize strain
readings. Prior to mating the sensors, a flex circuit made of kapton that has been
25
coated and laser cut in a specific circuit pattern is sandwiched between the two
sensors layers. A detailed description of the design and manufacturing process can
be found in reference [3]. These sensors sense pressure through a change in resistance
of the galinstan as the channel walls deflect when normal pressure is applied to the
completed sensor. The change in resistance corresponds to a change in voltage, which
is then calibrated to correspond to the pressure value. Each individual sensor is
housed in a "chele,"which are all connected through the Polipo garment, a wiring
system developed to accommodate system requirements and human range of motion
requirements. The final Polipo design, which integrated seven strands of copper
wrapped polyester per sensor vest, gives the wire a resistance of 0.6 ohms/meter,
while the polyester core allows it to be very durable and flexible, but the wiring itself
was not elastic or electrically isolated. The wire was sewn in a zigzag pattern to
achieve elasticity. The cheles housed the sensors, and the sensors were held in place
by soldering the flex circuit with the copper wiring mentioned above. As the wires
stretch with movement, the ends of the wires are fixed into place with hot glue. The
cheles and the rest of the Polipo were connected to a conformal base layer using
Velcro, and protected by another conformal cover shirt to prevent catching of the
wires or movement of the sensors.
According to Anderson, the pressure-sensing system achieved both high weara-
bility and utility, however, a design concern mentioned for future iterations was im-
proving sensor wiring durability, which proved to be a limitation after several hours
of wear inside the spacesuit performing EVA motions. Tears in the elastomer caused
sensor failure, and the sensors performed sub-optimally under static loading due to
creep effects and hysteresis. Another important area of future work mentioned was
to improve manufacturability such that the process is less highly-skilled, takes less
time, and fewer sensors fail during the construction process.
In an effort to capitalize on Anderson's design suggestions for future iterations of
the low-pressure sensing system, two major possibilities were investigated to address
the durability and manufacturing process concerns mentioned above.
In order to address manufacturing concerns, the possibility of using a 3D-printed
26
sensor. rather thaii a hand-manufactured sensor. was investigated. The W'yss Insti-
tute for Biologically Inspired Engineering at Harvard developed a 3D-printed carbon
grease sen1sor that could efficieitlv and effectively sustain an electric current, shown
in Figure 3-1. Carbon fiber nanotnlbes are suspended in grease. and contact between
the llanotubes creates a complete circuit to sustaim an electric current when a voltage
is applied. After viewing preliminary resistance tests conducted by colleagues at the
WvYss. it was determined that these 3D-printed sensors prvecd to be less reliable ill
their pressure measurements because naliottibe shifts led to inconsistient resistances
across each sensor. This was verified with arbitrary resistance measurements using a
voltmneter. The 3D-printed carbon grease sensors were not pursued.
Figure 3-1: Printed carbon-grease sensor with electrode extensions. (Image Source:
Wyss at Harvard, 2014)
For (irability concerns, a conniercial replacement for the hand-sewn copper
wiring was sewn in order to improve garment elast icitv and iinhnize tearing where the
copper wiring met the sensor. A suitable onie-stranded version of a conductive tape
was found through AMOHR Tecinisehe Textilien GnmbH. a company in Germany
that produces technical narrow fabrics for various purposes. AIMOTAPE Conduct
Nylon + Elastoner #45708. containing 2 insnlated copper strands was custom or-
dered as a replacement for the Polipo. which can be seen iii Figure 3-2. The AIOHR
two-stranded conductive tape was implemented in a new version of the Polipo by
CostnmeWorks in Somerville. MA. The original galinstan sensors, which are difficult
27
to manufacture, were used ilI the second version of the Polipo. however, due to seiisor
nmanufacturing issues leading to sensor failure. the second version of the Polipo was
not tested in the following experiments.
Figure 3-2: AT\(OHR two-stranded conductive tape used for second Polipo iteratioll.
3.1.2 Novel High-Pressure Shoulder Sensor
The Pliance sensing system developed by Novel GmbH. a German comnpaimny that
specializes in dynamic pressure distribution measurement technology, 'an be used
for an accurate mleasiuremlelnt of pressure 1(d load distribution on boti 1(ard and
soft surfaces. The Pliance system was connected to a range of flexible, elastic seil-
sors iade from capacitive transducers with high-tecb elastomers. These sensors are
calibrated through pre-determined loading sequences so as to create a baseline for
future measurements. guarantee accracv amd generate reproduciile data [8]. The
accompanying Pliance software gives the user the ability to acquire and store pres-
sure (istribuition data. view absolute pressure values in each sensor of the sensor ilat
network. playack mileasuremlelnts. and view maxiium1111 pressure. force 81(1 contact
area. The particular sensor used in our experiment and past experiments is a nodi-
fied S2073 sensor mat approximlaitely 22.4 cm x 11.2 cm with 128 individual senlsors
arranged in a grid of 1(6 by 8. Each sensor is 1.4 (111 ill length and width and can
measuire pressures between 20-600 kPa at a resolution of approximlately 1 kPa. The
Pliance systeill uses tell 1.2 V nickel metal hydride batteries with 2000 mAh. and
the sensor is rul at 330 mA. While the data collection rate can be adjusted. for the
purposes of our experiment, the data, was recorded once every 0.02 s (50 Hz). The
28
sensor imat was kept in place using the Polipo's base layer mentioned above, wvhich
was equipped with a rectaigular pocket interface that housed the Novel sensor mat.
Low-Pressure High-Pressure Novel APDNI Inertial
Polipo sensors sensor and hardware 'MeasurementUnit
A) B) C)
Figure 3-3: Experimental Sensor Systemis: A) Low-pressure Polipo sensors, B) High-
pressure Novel shoulder sensor C) APDM Opal inertial measurement unit. (Image
Source: Anderson. 2014)
Prior to any experinients. the Novel sensor is calibrated to ensure accurate data
collection during official mneasurenment trials. The calibration device used ws also
provided by Novel GmbH and was developed specifically for use with sensors devel-
oped by Novel and their Pliance sensing system. The calibration device consists of
an inflatable rubber bladder that is housed by secure rigid plates. The sensor be-
ing calibrated is placed on the calibration board and centered within the alpparatis.
Compressed air is then fed into the device, thereby exerting pressure on the sensor
nat. The Novel software provides caliiration steps to lhad the sensor mat at vain-
ous known pressures in order create calibration curves create( within the software.
Calibration files are stored for subsequent testing.
3.1.3 APDM Inertial Measurment Units
The APDM Opal Inertial Measurement Unit (IMU) Sensing systeii (Portland. OR)
consists of three accelerometers, three gyroscopes, and three nagnetometers. A
Kalnan filter integrates these signals into an orientation quaterion for each IMU.
The IMUs were placed in-phine with one another to optimize the output for isolated
joint movements, but their relative orienitations allow the detection of off-axis rota-
tions [3]. Three sensors were mounted internally on the upper arm. lower arm. and
29
Low- Pressure Polipo --Sensor Network
High-pressure NovelSensor Mat
Body MountedOpal IMUs
Figure 3-4: Placeineit of the ill-suit sensor systems. (Image Source: Anderson. 2014)
chest. Three cxternally imounted sensors were correspondingly iouinted oil the up-
per and lower spacesuit ami and suit torso. Each sensor is 4.8 x 3.6 x 1.3 ciii and
weighs approxiinately 21 g. Tl he gyroscopes and imagnetonieters were recalibrated
before placed on each sul1ject to take into account the iagnetic environment and
inimilize the gyroscope drift over tiie. They are powered by a lithiuiI battery at 3.7
V nloiliniaI, nd the imiaximumiliii current through the sensor is approxiimately 56 mA.
IMU seisoi data was collected wirelessly and continuously synchronized in real time.
3.2 Spacesuit Testing Experimental Design
This experiment was performed using two subjects in the David Clark Launch and
Entry Development Suit. The suit was pressurized aid tested at venting pressimre
(0.25 psi). iiltermedliate pressure (2.5 psi). and full pressure (:3.5 psi). While the
EIU defines 4.3 psi as "full pressure . David Clark pressurizes their suits to 3.5 psi
ill order to iicrease mobility 1)it ,minitai a smaller safety mgin for oxygen partial
pressure requirements. They wvere asked to perforn a series of upper body notions
inside the spaceslit while lying iii the recumbent position. These series of upper-
body motions is niilmed at characterizing') the hunan-suit interactions. Three isolated
joint nmovenmenits vere evaluated: elbow flexion /extension. shoulder flexion/extension.
and shoulder abduction/adduction. i addition. one nmulti-joint functional task was
evalulated: the cross-body reach.
Elbow Flexil/Extenslo VThe subject stands away from the donning stand supported by theirown effort. Beginning with both arms relaxed at their side, palms k s Dofacing anterior, the subject bends the anis at the elbow through s 'their maximum range of motion. The subject then releases to therelaxed position. MO M
Shoulder Fexion/LxtensionThe subject stands away from the donuing stand supported by theirown effort. Beginning wsith both anns relaxed at their side, thesubject bends the arms at the shoulder through the sagittal plane.The subjects move through their maximun range of motion. Thesubject then releases to the relaxed position.
Shioulder Abduction/AdductionThe subject stands away from the donning stand supported by theirown effort. Beginning with both arns relaxed at their side, thesubject bends the anns at the shoulder through the coronal planeThe subject moves through his or her mAximumi rangP ot motion
The subject then releases to the relaxed position
Cross-Body ReachThe subject begins in a relaxed position and reaches across theirbody to touch their hip on the opposite side. The subject mos atheir ann up to chest level and sweeps in front of their body. Whenthe arm is extended in front of the shoulder, the subject touches thehelmet on the same side The niovement is then repeated with theopposite arm.
Figure 3-5: Descriptions of the four upper body motions performed during the space-
suit experiment: three isolated joint notions (elbow flexion/extelision. shoulder flex-
ion/extension. shoulder abduction/adduction) and one functional task (cross bodyreach). (Image Source: Anderson. 2014, Hilbert et al. 2014)
The test protocol consisted of 15 repetitions of the four different motions inside
the spacesuit. These repetitions were divided into three groups of five repetitions
to allow for assessment of fatigue or changes ill biomnechanical strategies.
XVere divided into movement groups such that the order was counterbalanced within
the groumlp [3]. Prior to the test. subjects were trained on each motion and allowed
to practice it until they were comfortable ill order to maximized mnotion coilsistency
duirilng the experiment. The subject performned each notion iii the prescribed order
of the movement group, with no less than a 5-minute break between each movement
group in order to (ollect subjective feedback and to allow the subject to rest. After
all three imovment groups were completed, there was an intermittent rest period
to increase the pressure iii the suit. The subject was first tested in the unsuited
condition, and then at the corresponding test pressulr('s in the suit. The pressure
profiles and joint angles were recorded throughout the experiment. A representative
experiment schemlati( is showii in Figure 3-6, and the full experimental test plan can
31
I
Motionls
Movement Group 1 Movement Group 2 Movement Group 3
H 11 12 13 14 13 I1 14 12 12 14 11 I3
11: Elbow Flexion/Extension12: Shoulder Flexion/Extension Si vvvr.13: Shoulder Abduction/Adduction14: Cross Body Reach S2 r
Figure 3-6: Experimental Design Test Protocol: Each imovenent group consists of a
counterbalanced ordering of the motions. The motions studied were: three isolated
joint iot ions (elbow flexion/extension. shoulder flexion/extension. and shoulder ab-
duction/adduction) and a fiictional task motion (cross body reach). In each move-
iment group. the specific nmotion was repeated 5 tinmes for a total of 15 repetitions per
mlotionl.
3.3 Marine Protective Gear Experimental Design
In an effort to expand the applicalbility of the sensor systems. two rounds of experi-
ments were performed in conjunction withIi Protect the Force. a strategic consulting
firm specializing in product development for the U.S. aried forces.
Infantry soldiers and officers are a central comnponent of ground forces in the Ma-
rine Corps anod other branches of the military. According to the Marines, infantrymen
are trained to locate, close with and destroy the enemyn 1y fire and umaneuver, or repel
the eiemv's assault by fire aiid close co1bat. Riflenem serve as the primary scouts.,
assault troops and close colmlbat forces within each infantry unit. Crucial to combat
iission effectiveiness is ensuring each Marine's safety. However. in order to provide
safety in the form of heavy armiiior, often physical mobility aid strength must be less-
ened or compromised to carry heavy loads of arimor in addition to the gear Marines
are required to carry. Iii an effort to provide lightweight but effective armmor to lesseii
32
he found inl Appendix A.
heavy loads and increase imobility while wearing armor. the Marine Corps System
Command has developed several prototypes of advanced larine protection gear as
alternatives to the current gear provided to Marines.
Both experiments were performimed with the same subject ill (lifferelt proteetion
gear configiiratioiis: 1) the interim capability, USMC Plate Carrier (PC) and neck
plates. 2) the current capability. USNIC Improved Modular Tactical Vest (IMTV), 3)
the newly designed Ballistic Base Layer (BBL) protective garment and 4) the future
capability, the plate carrier combined with the BBL protective garment. Different
configurations of the protection gear were tested for their mobility. the shoulder con-
tact pressure, aid the subjective evaluation for comfort. fatigue, and mobility. This
is critical in order to ensure the future capabilities being currenItly developed will
provide an improvement in the design and the use of the protection gear.
Figure 3-7: Different US\IC protection gear conifiguratiois used during testing
One subject was tested in the Man Vehicle Laboratory. at the Massachusetts Iii-
stitute of Technology (Cambridge, MA) oil two different occasions (December 2015
and Jaimuary 2016). The subject corresponded with the Narine infantrymen anthro-
polmetrics provided by Protect the Force as seen iln Table 3.1.
Similar to tlie spacesulit test experimental desigm. the experiment colmsisted of
15 repetitions divided into three groups of five repetitions of four different mo-
tions inside the spacesuit. Three isolated joint movements were evaluated: shol-
33
Table 3.1: Anthropometrics from typical Marine compared to anthropometrics of
subject usedMarines [ Subject
Height 5'8" 5'11"Weight 176 lbs 190 lbs
Waist Circumference 34.5" 34.5"Chest Circumference 40.5" 38"
der flexion/extension, the vertical shoulder abduction/adduction (defined as simply
the shoulder abduction/adduction in Figure 3-5, and the addition of the horizon-
tal shoulder abduction/adduction shown in Figure fig12. The multi-joint functional
cross-body reach was also evaluated.
A
SHOULDER ADOUCTION (A),ABDUCTION (B)
Figure 3-8: Horizontal shoulder abduction/adduction. Beginning with their arms
extended at shoulder height, shoulder width apart, the subject bends their arms at
the shoulder in the transverse plane. The subject moves through his or her maximum
range of motion. The subject returns to the initial start position then releases to the
relaxed position.
This motion is particularly useful to combine basic motions performed by Marines
during operations: reaching helmet on its side, reaching opposite side of the body, or
extending the arm in front of the body. The subject performed each motion in the
34
prescribei order (Iof the movement group. with n1o less than a 5-iiiiinute break 1b)etweeli
each movenient group ill order to collect subjective feedback an( to allow the subject
to rest. After all three inoveiiient groups were conmlleted(. there was ain iiiteriiiittenit
rest period. The subject was first tested( in the unsuited condition. ald then with the
corresponiiig protective gear coiifiguratioiis. At the en(l of the second experinelit
following all iotiolis outlined in the experimienital design, the subject )erufoled a
set of rifle carry motions in Configurations 1 an(l 4. The rifle carry iotions were
perforimled ill the followillg sequence for each condition: 5 repetitions. 10 second pause,
aild 5 repetitioils for a total of 10 rifle carry repetitions per configuration. The rifle
(ally motiol1s were performed with a 7.2 lb pipe similar in shape to an M16 A2 rifie.
The shoulder contact pressure profiles al(l joint angles were recorle( trlonghoIt the
experimeiit. A representative experiment scheiatie is shown in Figure 3-9.
Movement Group 1 Movement Group 2 Movement Group 3
11 12 13 14 j3 11 14 12 12 14 11 13
11: Shoulder Flexion/Extension12: Shoulder Abduction/Adduction vertical S1 / \/\A13: Shoulder Abduction/Adduction horizontal14: Cross Body Reach S2 V0
Figure 3-9: Protective Gear Experimental Design Test Protocol. Each movement
group consists of a couiiterbalanced ordering of the motions. The motions were: three
isolated joint motions (shoulder flexion/extension, shoulder abduction/adductioli ver-
tical. shoulder abduction/adduction horizontal) and a functional task motion (cross
body reach). In each imoveineit group. the specific motion was repeated 5 times for
a total of 15 repetitions per motion.
35
Chapter 4
Novel System Results and
Discussion
The following chapter presents a variety of analysis intended to provide an under-
standing of the human-suit shoulder interface. The diagram in Figure 4-1 shows the
presentation of the data and the orientation of the Novel sensor with respect to the
subjects shoulders. This diagram shows that the lower portion of the sensor with
respect to the diagram corresponds to the anthropometric region toward the clavicle
and front of the body, whereas the upper portion overlays the back of the shoulder,
toward the shoulder blade.
4.1 David Clark Experiment
For the David Clark Launch and Entry Development Suit, two main categories of
data are presented for the Novel pressure sensing system: 1) the overall pressure dis-
tributions and 2) the pressure profiles seen in each of the motions. For the following
results, data from the elbow flexion/extension was excluded as it was deemed less
relevant to the shoulder portion of the human-suit interface. Hilbert first determined
that analysis of pressure distributions aids in determining which areas of the shoulder
are experiencing the highest pressures during upper body motions and providing a
visual understanding of what is happening at the human-suit shoulder interface. Ad-
36
Diktal fnd of Shoulder Ba dg i u w suusc 111m Im I
Figure 4-1: Orientation of the Novel Sensor. The orientation Corresponds to the
information i i each pressure (listtribution figure. Coloring is for orientation and is not
related to pressure scales. (Image Source: Hilbert 2015)
ditionally, analyzing pressure profiles as a function of tie provides how the pressures
vary over the course of a particular movement while allowing us to determine whether
there is any time effect [8]. Upon visual inspection we can claim that Subject 1 had a
narrower an(d taller body frame than Subject 2. which will be critical to the discussioli
of varying contact pressures.
4.1.1 Pressure Distributions
The pressure distribution mnaps for Subject 1 and Subject 2 are shown in Figures 4-2
and 4-3. The figures show the pressure distributions as a color scale representing the
pressure in kPa. For practical reference. 100 kPa provides approxinately the same
pressure as a 1 kg (2.2 lbs) weight oi one square centimeter of the skin. For each
of the motions at each of the pressurized conditions. the pressure (listributioli map
represents the pressure (listribution at the peak of the movenient, or the pressure
distribut ion at the moment when the highest pressure appeared.
Looking at Subject I's neasuireients in Figure 4-2. it is evident that as suit
presslurizatloll increases. contact pressure increases as well. From visual inspection,
it is not clear whether any one motion has higher Overall pressures than the other
motions. At 0.25-psi vented condition. pressure is concentrated along a line just above
37
Subject 1
Sh FI/Ext Sh Abd/Add CrBReach
IA
Ln~
4,)
CL
(n
PI
I
I
160140
120100
80
6040
20
0 kPa
160140
120
10080
6040
200 kPa
160
140120
100
8060
40
20
0 kPa
Figure 4-2: Contact Pressure listributions for each inotion at ( (ch Cressurized eon-
dition for Subject 1.
38
the clavicle for all three motions, likely over soft musculature near the top of the
shoulder as was seen in Hilbert's results. These areas of pressure concentration (peak
of ~75 kPa) are accompanied by a secondary area of pressure concentration at the
most distal end of the lower edge of the sensor. Likely, the sensor was being slightly
pinched by the chest and the armpit in each of the motions. However, after dynamic
inspection of the data in the form of pressure distribution videos, the pressure line can
also be attributed to a crease in the Novel pressure sensor at the peak mobility point
of a motion. During motions where the subject retains high mobility, a crease would
form in the mat at the top of the shoulder due to the rigid nature of the mat, and
this produces artificially high pressure values. At the 2.5-psi intermediate-pressurized
condition, the pressure (peaks between -100 and ~140 kPa) is now concentrated in a
region centered just above the end of the clavicle toward the acromion for all motions.
At this pressure and higher pressures, the Novel mat did not seem to demonstrate
any creasing, most likely due to limited mobility and the mat pressing against the
suit. The peak pressure is highest for the cross body reach, followed by the shoulder
abduction/adduction, and lastly the shoulder flexion/extension, but the location and
shapes of the pressure distributions are nearly identical in all motions. At the 3.5-psi
full-pressurized condition, the pressure distributions maintained the size and shape
of the peak pressure locations for the intermediate pressure condition, however, the
magnitudes of the peak pressures reach -160 kPa at the clavicle and acromion.
Looking at Subject 2's measurements in Figure 4-3, the pressure distributions
follow similar trends to Subject 1's such that as suit pressurization increases, con-
tact pressure also increases. At the 0.25-psi vented condition, the artificially high
crease pressure band is only seen in the shoulder flexion/extension. For the shoulder
abduction/adduction and cross body reach, there is a large but low-pressure (-40
kPa) peak at the top of the shoulder toward the clavicle and chest. At the 2.5-psi
pressurized condition, the size of the peak pressure area is reduced and becomes
more concentrated in the acromial region toward the distal end of the shoulder for
all motions. The shoulder abduction/adduction experiences the highest peak pres-
sure (-120 kPa), followed by the shoulder/flexion extension (-100 kPa), and the
39
Subject 2
Sh Fl/Ext Sh Abd/Add CrBReach
En
Lfl
CL
U')
C0
I
I
I
140
120
100
80
60
40
20
0 kPa
140
120
100
80
60
40
20
0 kPa
140
120
100
80
60
40
20
0 kPa
F'igiire 4-3: Contact pressure distributions for each 1i1otion at each pressurized cou-
dition for Subject 2.
40
cross body reach (~70 kPa). For the 3.5-psi pressurized condition, the size, shape,
and location of the peak pressures remains almost identical to the 2.5-psi pressurized
condition. The peak pressure locations are concentrated at the top of the shoulder
toward the acromion for all three motions. The peak pressure magnitudes for the
shoulder abduction/adduction and cross body reach approximate to ~120 kPa, with
the shoulder flexion/extension peak pressure magnitude reaching -140 kPa at the
acromion.
Comparing subjects we see that Subject 1 experiences higher pressure than Sub-
ject 2 in all motions at the fully pressurized condition (3.5-psi pressurization). It
is interesting to note that for both subjects, pressure was concentrated in a consis-
tent location across all motions: approximately on the acromion and just above the
clavicle and the soft musculature at the top of the shoulder.
4.1.2 Pressure Profiles
Pressure profiles as a function of time are now considered at each pressurized condition
for each subject, shown in Figures 4-4 through 4-7. For each motion, selected pressure
profiles for different sensors are plotted for each of the three movement groups. The
individual sensiles are chosen based on whether they experienced the peak pressure
on the mat at any moment in time during the motion repetition, and they represent
the highest magnitude profiles of each general trend of sensor response. Since it
was determined that at lower pressurized conditions where the subject retains high
mobility the Novel mat develops a crease and reads artificial pressures, the pressure
profiles of the lowest pressurized condition, 0.25-psi, are not shown.
All plots have the same scales: the y-axis being pressure in kPa from 0 to 160 kPa,
and the x-axis being a normalized time axis. Each cube in the grid represents a 0.1
sec interval in the horizontal direction and a 20-kPa interval in the vertical direction.
Normalizing the x-axis and plotting each of the profiles on the same time scale allows
for easier comparison. While each motion included five repetitions per movement
group, only the two most consistent repetitions are shown since the subjects found
it very difficult to remain consistent in the recumbent position. All motion pressure
41
U'
Subject 1- 2.5 psi pressurized conditionMovmt. Group 1 Movmt. Group 2 Movmt. Group 3
-&j
.0
U
U
.1
11I-t
A- -&jr NFigure 4-4: Contact pressure profiles for all motions in the 2.5-psi pressurized condi-tion for Subject 1.
profiles are shown, however in some cases, it is impossible to identify the profile of
the motion.
Starting with Subject 1, we will analyze the pressure profiles by motion. The
shapes of the general profile for the shoulder flexion/extension are consistent for both
the 2.5 psi pressurized condition and the 3.5 psi pressurized condition. The shoulder
flexion/extension appears to have two distinct peaks per repetition in approximately
the same location at the top of the shoulder where the second peak is only a sensile
or two closer to the chest than the shoulder blade. Analyzing the subject video
taken during the experiment, it appears that the subject would shift inside the suit
during the beginning of the motion during flexion, and then shift again after the
peak of the motion during extension, hence the slightly higher contact pressures
seen in the second peak. The shift in full body position can be attributed to air
displacement in the soft suit in the recumbent position since the subject did not have
42
El
Subject 1- 3.5 psi pressurized conditionMovmt. Group 1 Movmt. Group 2 Movmt. Group 3
UJ
CA
*I t
Vt t tj
~J4M
ra
L) 4!k
Figure 4-5: Contact pressure profiles for all motions in the 3.5-psi pressurized condi-tion for Subject 1.
43
-I
the stability of standing on his feet. There is also a constant contact pressure seen
at the top right corner, which corresponds to the shoulder blade. This is due to
resting on the shoulder blade and back in the recumbent position and the shoulder
activity that occurs in the shoulder blade during the shoulder flexion/extension. For
the shoulder abduction/adduction, the general profile for the peaks are consistent,
however, the magnitudes of the peaks in the 3.5 psi pressurized condition are highly
inconsistent between movement groups. During the shoulder abduction/adduction,
the same body shift due to air displacement in the suit occurred as it did in the
shoulder flexion/extension. There is an initial spike in contact pressure as the body
shifts toward the feet in the suit and initiates contact at the top of the shoulder, then
again as the body shifts back upward toward the head and initiates contact during
the contrary movement. In the cross body reach movement, the pressure profiles
change in between pressurized conditions. In the 2.5 psi pressurized condition, there
are three peaks: the two larger peaks occur at the top of the shoulder during the
motion, and there is a much smaller peak between the two larger peaks that occurs
at the shoulder blade. These peaks coincide with the multiple motions necessary to
complete the functional task motion. In the 3.5 psi pressurized condition, the same
two major peaks occur without the smaller peak occurring at the back of the shoulder.
Looking next at Subject 2's pressure profiles, the shapes of the general profile for
the shoulder flexion/extension are consistent for both the 2.5 psi pressurized condition
and the 3.5 psi pressurized condition. Unlike Subject 1, the shoulder flexion/extension
appears to have only one distinct peak per repetition in approximately the same lo-
cation at the top of the shoulder as Subject 1. While the same body shift was seen
inside the suit as Subject 1, due to the different anthropometries between subjects,
the suit displacement had less of an effect on Subject 2 since Subject 2 had over-
all larger anthropometric measurements. For the shoulder abduction/adduction, the
general profile for the peaks are consistent and nearly identical to the shoulder flex-
ion/extension profile. Before the large prominent peak, there is a smaller, less distinct
peak of contact pressure that occurs on the back of the shoulder toward the armpit
(top left corner of the diagram) during the 2.5 psi pressurized condition. This small
44
Subject 2- 2.5 psi pressurized condition
Movmt. Group 1 Movmt. Group 2
B~11wi
Movmt. Group 3
. rf.
Figure 4-6: Contact pressure profiles for all motions in the 2.5-psi pressurized condi-
tion for Subject 2.
back-of-shoulder peak also occurs during the 3.5 psi pressurized condition, but not in
all three movement groups. In the cross body reach movement, the pressure profiles
remain extremely consistent between pressurized conditions, only the magnitudes of
the first large peak changes. Subject 2's cross body reach experiences only two ma-
jor peaks instead of three as seen in Subject 1: initial large park at the top of the
shoulder, and a second smaller peak occurring at the back of the shoulder blade next
to the arm pit.
Comparing the pressure profiles between subjects, it appears that while the general
pressure distributions appear to be similar, the pressure profiles give the resolution
to observe distinct differences between subjects. The primary location for contact
pressure in Subject 2 is located slightly to the left of the primary location for contact
pressure in Subject 1. This can be for one of two reasons: either the mat placement
was slightly different between subjects and so the primary locations for both subjects
45
XLLI
.0
U
Movmt. Group 1
Subject 2- 3.5 psi pressurized conditionMovmt. Group 2 Movmt. Group 3
-J
t
4*1
r rNZ23A
Figure 4-7: Contact pressure prtion for Subject 2.
ofiles for all motions in the 3.5-psi pressurized condi-
6
xLU
-
-o
at
U fa It
corresponds to the same anthropometric location on the body (the acromion), or the
differences in anthropometric measurements between subjects caused the primary
contact pressure location to vary slightly between subjects but remain in the general
area at the top of the shoulder. The only motion profiles that vary significantly
between subjects are the pressure profiles of the cross body reach motions between
subjects. While the two peaks seen for Subject 1 are both concentrated at the top of
the shoulder, the two peaks for Subject 2 shift from the top of the shoulder to the back
of the shoulder blade. This supports the claim that for functional movements, contact
pressure locations can vary depending on anthropometric measurements. Another
example is demonstrated during the instances in which there is contact with the
shoulder blade: Subject 1 tended to experience contact pressure on the inside of the
shoulder blade toward the spine, whereas Subject 2 experienced contact pressure on
the outside of the shoulder blade toward the armpit.
4.1.3 Statistical Analysis
In order to more clearly understand the effects of pressurization conditions, motion
type performed, and subject variability, a statistical analysis was performed. Five
peak pressure values were extracted from the data for each motion during each move-
ment group. Each subject had a total of fifteen peak pressure values for each motion
during each condition. The mean and standard deviation were calculated for the peak
contact pressures, and a statistical analysis was performed. A multi-factor ANOVA
(Factor A- motion, Factor B- pressurization condition, Factor C- subject) was per-
formed, as well as Kruskal Wallis tests since shoulder abduction/adduction at 0.25
psi and cross body reach at 2.5 psi for Subject 2 were not normally distributed. For
all tests, an alpha value of 0.05 was used to determine significance.
First, we will analyze the effect of pressurization on mean contact pressure. Main
effects for pressurization condition (p <0.0005) were found with both the multi-factor
ANOVA. The effect of pressurization on mean contact pressure across motions can be
seen in Figures 4-8 and 4-9. For all three motion types in both subjects, mean contact
pressure increases, significantly in most cases, as suit pressurization increases. For the
47
shoulder flexion/extension, both subjects experienced a significant change in contact
pressure between vent pressurization and full pressurization as well as intermediate
pressurization and full pressurization. For the shoulder abduction/adduction, Subject
1 experienced a significant change in contact pressure between all three conditions,
whereas Subject 2 did not experience any significant change in contact pressure be-
tween the intermediate and full pressurization conditions. Finally during the cross
body reach, Subject 1 experienced a significant change in contact pressure between
vent pressurization and full pressurization as well as vent pressurization and inter-
mediate pressurization, but no significant change was found between intermediate
and full pressurization. Subject 2 experienced significant changes in contact pres-
sure across all conditions during the cross body reach. Since the pressure profiles
reflect the same data as the pressure distributions seen earlier, all vent pressure pro-
files recorded and considered in the statistical analysis are likely higher than actual
pressure experienced by subjects since peak data reflects pressure during the mat
crease.
Next, we will analyze the effect of motion type on mean contact pressure. Main
effects for type of motion were not found (p=0.73) for the multi-factor ANOVA.
The results are presented in Figures 4-10 and 4-11. There is also no single motion
that produces higher contact pressure than any other motion across all cases. At
vent pressurization, Subject l's shoulder abduction/adduction contact pressures are
significantly lower than the other two motions. However, at the same pressuriza-
tion, Subject 2 experiences the highest contact pressures during the shoulder flex-
ion/extension and the lowest contact pressures during the cross body reach, those
being significantly different from each other but neither from the contact pressures
found during shoulder abduction/adduction. It is difficult to determine the validity
of motion type results during the vent pressurization condition due to artificial mat
pressures, so while there are no conclusions to be drawn from the results, the re-
sults would not be considered for recommendations. At intermediate pressurization,
there are no significant differences in contact pressure between any of the motion
types. At full pressurization, the shoulder abduction/adduction differs significantly
48
2
0101
13
0 Julder Flex)ExtL r'lrAbdSAdd
7 rssbody Reach
60 -
20
00-
40
20-
Vent Pressure Intermediate Pressure
Figure 4-8: Effects of pressurization on imean contact pressure for Subject 1.
J43-
Shoulder Flex-ExtShoulder Abdc i
---iCrossbody' Reach
100
2 IsO
4u
velit Pressure Irterr'rede Pressure
Figure 4-9: Effects of pressIIrizatioII OH mIea coutact l)ressure for Subject 2.
49
Subject 1
Full Pressure
Subject 2
Full Pressure
250t Subject 1Vent Pressure
viIntermediate PressureFull Pressure
200C
1501
0
0Rud Fle Ex r ouidr AtxdAdd r' dy Reach
Figure 4-10: Effects of motion type on mean contact pressure for Snbject 1.
Subject 2
Vest PressureI1Intermediate Pressure-Full Pressure
IL
Shoulder FlexiExt Shoulder AbdAdd Crossbody Reach
Figure 4-11: Effects of motion type on mean contact pressure for Subject 2.
50
1 2
intermediate Pressurization
60
40
Shoulder Flex,.Ext Shoulder Abd/'Ad Crossoody Reach
Figure 1-12: Effect at subject on mean contact pressure for iflterllediate pressuliza-
tion.
Full Pressurization
- ubI IDuI 2
200 -
IOU -
Shouldei Flex Ext Shoulder Abd/Add Crossoody Reach
Figure 4-13: Effect of subject on iean contact pressure for full pressurizationl.
11
51
d
from both the shoulder flexion/extension for both subjects. However, in Subject l's
case it is significantly higher than the other two motion types whereas Subject 2's
case demonstrates that it is significantly lower than the other two motion types. It
can be said that at intermediate pressure the contact pressures experienced are all
similar between motions types, and at full pressure the contact pressures experienced
are similar between the shoulder flexion/extension and the cross body reach but not
the shoulder abduction/adduction.
Finally, we will analyze the effect of subject variability on mean contact pressure.
Main effects for different subjects were found (p<0.0005). The results are presented in
Figures 4-12 and 4-13. At both intermediate and full pressurization, Subject 1 expe-
riences higher contact pressures than Subject 2 with every motion type. In the cross
body reach at intermediate pressurization and in the shoulder abduction/adduction
at full pressurization, this difference in contact pressure is statistically significant. For
reasons mentioned above, results at vent pressurization are not shown. Subject vari-
ability can be attributed to two major factors: 1) subject anthropometry, which can
determine how often they make contact and how high the contact pressures will be,
2) subject experience, which determines how experienced the subject is at mitigating
contact within the suit to maintain their comfort and increase the amount of time
they can tolerate spending in the suit.
52
4.2 Protect the Force Armor Gear Prototype Ex-
periments
The advanced Marine gear aims at distributing loads and pressures more evenly across
the shoulders as opposed to having concentrated areas of extreme pressure at the top
of the shoulders. The Novel pressure sensor was located at the top of the shoulder,
and the data will be displayed in an identical fashion to the shoulder data from the
David Clark spacesuit shoulder experiment.
The pressure distribution maps for the different configurations are shown in Fig-
ures 4-14 and 4-15. The figures show the pressure distributions as a color scale
representing the pressure in kPa. For each of the motions at each of the pressur-
ized conditions, the pressure distribution map represents the pressure distribution
at the peak of the movement, or the pressure distribution at the moment when the
highest pressure appeared. The movements that provide the most insight on changes
in pressure distributions across the shoulder are the vertical and horizontal shoulder
abduction/adduction movements.
Figure 4-14 shows the pressure profiles during moments of peak pressure for the
four separate suited configurations and four separate motions in kPa. The top two
configurations are the configurations without the BBL (the potential future capabil-
ity). When the Novel mat is used on top of the shoulder during motions of high
mobility, it causes the mat to bend, which is shown across all four conditions as a
diagonal increase in pressure across the mat. Configuration 2 (frog -shirt + IMTV)
show the highest overall pressures distributed across the top of the shoulder. The
more lightweight current capability, Configuration 1 (frog shirt + PC), also shows
heavy pressures across the top of shoulder as well as mat bending. The most signif-
icant comparison to make is between Configuration 1 and Configuration 4; both use
the PC but the BBL has also been incorporated into Configuration 4. The pressure
distribution across the shoulder is similar, however, the pressures in Configuration 4
are much lower overall across all sensors. This indicates the BBL has relieved the
wearer of some of the pressure/weight from the PC.
53
onCCt}
onICCC
(-7
rnor
ICCCU
on42C0
(-7
Sh. FI/Ext.
It'I I-T!
ShAbd/Add V. ShAbd/Add H. CrB Reach
fl pi~i~..m
J-t 71W-i'1-
A j.4. I
I
U
1009080
70
60
5040
3020
100 kPa
100
9080
7060
5040
3020
100 kPa
100
90
80
1060
5040
3020
100 kPa
100
908070
60
5010
3020
100 kPa
Figure 4-14: Pressure distributions of all motions for different US\JC arnior configu-
rati(1s.
During the horizontal aidiction/adhuetion. the weight of the arumor is plaeed
heavily (1 the shoulders. aid depell(ling on the widtll of the straps. either manifests
itself as an acute pressure point or more even distribution. In Configuration 1 anld
Configuration 2. the pressure distribution shows the iiat bendiig phenoiiienon. Ili
addition. the surrounding pressures are higher with the frog shirt and PC thian the frog
shirt and IMTV. While the IMTV is heavier., it is most likelv that the wider straps
of the INITV cause a wider (listributioli of pressure of the armor weight, thereby
relieving the subject of a concentrated pressure.
10090
8070
g 6050403020100 kPa
Figure 4-15: Pressure distributions for rifle carry motion for Configuration 1 (on left)
and Configuration 4 (on right).
Figure 4-15 shows the pressure distributions at the mnoment of peak pressure for ri-
fle movements between the two different PC configurations. The figure clearly delon-
strates that the BBL helps minimize pressure at the top of the shoulder when usiig
the PC. The frog shirt loes little to nmninze pressiures at the tops of the mnotionis.
Overall, it appears that the IMTV distriblites the weight of itself better than the PC
oii its owii does, eveni though the PC is 1mch lighter. However. the addition of the
BBL reduces the load of the PC ini some cases and is not helpful in others.
4.3 Conclusions and Future Work
These results yield no common conclusions across suit types or subjects. For the
David Clark Lauinch and Entry Development Suit. both subjects experieiice(d sig-
nificant contact pressures at the top of the shoulder and acromion. However, the
magnituides of contact pressures were significantly different between the two suilbjects
and furthermore, it was not clear whether certain imotions elicited more contact than
others. The effects of motion type oi contact pressure cannot be generalized across
subjects as they are likely affected by individual anthropomnetry, suit fit. and bionie-
chanics, but the information gathered for each subject can be used to decrease the risk
of astronaut injury when applied individually. The less experienced subject (Subject
1) experienced the highest pressures, but both subjects experienced discomfort on
the top of the shoulder over time.
The results yielded for the Protect the Force armored gear can draw some general
conclusions, but since only one subject was tested, further testing is necessary in order
to validate these conclusions. While heavier, the IMTV provides a better pressure
distribution than the PC due to its wider straps. When the BBL is incorporated,
it has the same effect as the IMTV (in terms of distribution) by distributing the
PC load across the shoulder. It also appears that this load exerts an overall lesser
force than the IMTV. The vertical abduction/adduction causes pressure across the
shoulder between all motions regardless of configuration. The IMTV and frog shirt
seem to provide an overall less pressure than the PC and frog shirt. During rifle carry
motions, the BBL significantly offloads pressure from the PC as compared to the frog
shirt.
The most important point to address is the validity of the results. While the
Novel sensor system proves to be state-of-the-art pressure sensing equipment, it may
not be the optimal equipment for the particular human shoulder application. When
placed at an interface with high mobility, the sensor is susceptible to false, artificial
readings caused by creases in the sensor. As a future alternative, it would be ideal
to incorporate a network of small, variably placed sensors across the joint and rest of
the body. A sensor such as the Novel S2012 shown in Figure 4-16, which is 2 cm in
diameter, if paired with many others, could get a general profile for pressure readings
across the shoulder while remaining small enough to gather data across a seemingly
flat surface.
Further studies should integrate the spacesuit pressure and joint angle data found
in other work with metabolic data in order to understand how fatigue and injury in-
fluence the metabolic work necessary for spacesuit operations. All of this information
would allow us to more accurately determine where injury is most probable, incorpo-
rate a quantitative measurement for fatigue, and ultimately influence air-pressurized
56
spacesuit design in the future.
Figure 4-16: Novel Single S2012 Sensor with 2 cin diaieter (Image Source: iiovel.(e)
57
Chapter 5
International EVA Capabilities
"The United States will seek to cooperate with other nations in the peaceful use of
outer space to extend the benefits of space, enhance space exploration, and to protect
and promote freedom around the world"-National Space Policy (2006)
5.1 A Case for EVA Standardization
Despite the fact that our collective EVA capabilities are advanced compared to other
capability requirements needed for a potential mission to Mars, there is a lack of
cooperation that causes difficulty when trying to develop facilities to accommodate
different suits. The most obvious interoperability requirement is hardware compati-
bility. The current NASA spacesuit, the EMU, has already been described in Chapter
2. The International Space Station (ISS) also uses the Russian Orlan suits for EVA
operations. While both NASA and Roscosmos are both currently developing newer
models than the ones mentioned, we will compare in-flight capabilities for simplicity.
Even though equipment and tools developed by NASA and Roscomos perform the
same functions in the same environemnt, differences in operations philosophies lead to
very different design solutions [10]. NASA's collection of EVA suits from B.F. Goorich
(Mark-IV IVA suit), David Clark (Gemini high altitude pressure suit), Hamilton Sus-
trand, and a handful of other companies indicates a very wealthy nation with many
designs to choose from, but it also indicates a non-linear EVA suit evolution [7]. On
58
the other hand. Russia has iever been a very wealthy nation. and the coinlbinati(oni
of linited funding. a single supplier (Zvezda). and organic national design philsophy
has served to create Russian EVA suits that are rugged. straight forward. and easy
to naintain ii-orbit [71.
Figure 5-1: R ear entry opening for Russian Orlaii-M spacsuit. (Image Source: NASA)
The spacesuit (.urr1enltly used by cosinionauts is the Russian Orlcan-MK imodel.
which is the fifth varint in the Orln series of scinli-rigid onle-piece space suit iod-
els designed and ianufactured by NPP Zvezda [15]. Unlike American EVA stilts.
Russian EVA stilts have had a direct evoluitionary path as they have all been built
by NPP Zvezda [7]. The Orln stilts were first used inl flight during Salytit-6 and
Salyut-7, anld variouis mnodels have beenl introduced for Mir and ISS operations. The
Orln spacesiuits are scinli-rigid: the enclosure incorporates a HUT. integrated with a
hehinet and miade of ahiiintinn alloyv, and soft stilt arins and 1lg enclosures [1]. They
inchidc a rear hatch entry through the backpack that allows it to be self-donned ill
approxiinately five miinutes. which is shown inl Figure 5-1. The Orlan suits comne inl a
59
"one size fits most" standard size that can be used by cosmonauts with various (but
limited) anthropometric characteristics. The Orlan suits also contain an integrated,
regenerative (closed-loop) life support system (LSS). The first three Orlan suits (Or-
lan, Orlan-D, and Orlan-DM) used a 20-m electric umbilical which served as a safety
tether and provided the power supply, radio communication, and telemetry. The
Orlan-DMA was the first suit that was fully self-sustaining, that is, it could be used
without the electrical umbilical because it was provided with a removable unit that
incorporated an electrical power source (battery), radio and telemetry system, and an
antenna-feeder device. The Orlan-DMA also introduced a second safety tether. The
Orlan-M, which was used on the ISS from 2001-2009, took into account the experience
of Orlan-DMA operations on Mir and the additional requirements imposed by opera-
tions on the ISS: 1) the suit's dimensions were enlarged, 2) an additional helmet-top
window and protective glass for the main window were introduced, 3) a calf bear-
ing and the third pressure bearing (elbow) on the suit arm were introduced, 4) one
of the safety tethers was given variable length, and 5) the carbon dioxide control
cartridge (CCC) capacity was increased. Power supply, radio comms, and telemetry
were available for both the self-contained mode and via the 25-m electrical umbilical
cord from the station. The service characteristics (mobility, donning/doffing, field of
view) and anthropometric ranges were improved from earlier models. The suit was
also provided with attachment points for Simplified Aid for EVA Rescue (SAFER).
The Orlan-MK model's main improvement is the installment of a mini-computer in
the Portable Life Support System (PLSS) backpack. The computer processes data
from the spacesuit's various systems, issues a warning in the event of a malfunction,
and outlines a contingency plan that is displayed on an LCD screen attached to the
right breast of the spacesuit [15]. The current Orlan spacesuit assembly weighs 238
lbs, operates at 5.8 psi with a 100% oxygen atmosphere, and has a maximum EVA
duration of 7 hours. It is designed for an on-orbit lifetime of 12 EVAs or 4 years
without return to Earth [11].
To compare, the current EMU spacesuit assembly was designed to accommodate
individuals ranging in size from the 5th percentile Asian female, to the 95th percentile
60
Caucasian male, which made a "one size fits all"design impossible [10]. While sizing
differences do not pose a problem for interoperability between suits, it does affect
which individuals can participate in the astronaut/cosmonaut programs. There are
significant hardware differences that make EVA cooperation difficult. While both
suits function perfectly well at vacuum, it is not physically possible for the EMU
and Orlan to go to vacuum simultaneously in the same airlock. First, the Shuttle
EMU is nearly four inches wider than the Orlan suit, which made it difficult for
the EMU to transit through the small Russian hatches [7]. The coolant loop and
sublimator water that the EMU and Orlan-M use in their respective life support
systems is also incompatible. While both suits use approximately 1 gallon for each
EVA, the Orlan uses distilled water for the sublimator function but adds silver ions
to the coolant water supply loop to extend its storage life [7]. In contrast, the EMU
uses iodized potable water for both the coolant and sublimator functions. If the
Russians must perform an EVA from the ISS airlock, they must empty the EVA
coolant loop supply of American water and substitute it with Russian water, then
purge and refill the supply with American water after the EVA [7]. Furthermore,
because of the unknown way in which the suits' respective coolant systems may
react over the long term to differing water supplies, it would be difficult to support
simultaneous EVAs. Another airlock discrepancy is in back-up oxygen supply tank
replenishment: the Orlan-M stored its back-up oxygen supply at 6,000 psi in reserve
tanks that can be easily detached and replaced on-orbit whereas the EMU's reserve
tank cannot be refilled with its 900 psi oxygen anwhere except on the ground due to
the inability to check for leakage while on-orbit [7]. In order to avoid decompression
sickness (DCS), decompression cycles also differ: the Orlan-M operates at 5.8 psi
which require a 30-45 minute nominal oxygen prebreathe time and the EMU operates
at 4.3 psi which requires a 4 hour oxygen prebreathe before it can go EVA from
the station's 14.7 psi sea level atmosphere. Thus, when designing for both the U.S.
and Russian EVA systems onboard the ISS, a new airlock was required. The Quest
Airlock, a joint airlock, attached to the ISS in 2001, and acts as a stowage area
for spacewalk hardware as well as a staging area for crew members preparing to
61
conduct a spacewalk [22]. Both suits also have their own airlocks on station [11].
With two spacesuits, three separate airlocks, plus hundreds of EVA hand tools in use,
the requirements on instructor, crew, and flight controller certification training are
enormous with several thousand hours of certification and proficiency work and need
to be condensed or simplified [10].
Another significant factor is the effect of non-hardware issues: non-native lan-
guages, training facilities on separate continents, and different task development
philosophies can present major problems when handling difficult or non-routine sit-
uations and can even create minor disagreements in everyday operations. There are
extensive challenges for interoperability during mission operations because during the
planning phase, personnel must integrate requirements from numerous foreign and do-
mestic sources [10]. For example, Russian and American crew members operate in
the EMU while performing EVA tasks on the Canadian-manufactured robotic arm;
this requires task/procedure integration, integration of the event into overall ISS op-
erations, establishment of flight rules, etc. [10]. The current solution to minimize this
complexity is EVA planning and integration responsibilities lie with the organization
whose suit is being used, however, this could be eliminated with one jointly-developed
suit for all operations on an international spacecraft or station. After planning, train-
ing the EVA tasks is also necessary, and in the previous example, while the task will
be trained by U.S. instructors, technical expertise for the task lies with the Canadians
[10].
At first glance, the Russian and EVA suit systems seem to share a resemblance
and they are very "functionally similar" in that they are both meant to carry out
the same functions [7]. However, while these two systems were designed to achieve
similar tasks, they are "the products of such disparate national outlooks, design
philosophies, operating parameters, and fabrication methods as to make them almost
incompatible" [7].
The concept of international cooperation with respect to EVA has not been com-
pletely neglected. After the ninth International Academy of Astronatuics (IAA) Man-
In-Space Symposium in Cologne, 1991, members of all national space agencies agreed
62
18012 9
Figure 5-2: The U.S. E\IU and Russian Orlan-M spaeesuit shown side by side. (Inage
Source: NASA)
to form an IAAA subgroup to exchange ideas on EVA interoperability and supply
reeoiinnleii(lations to solutions to EVA interoperability problems [7]. Iii 1992, the
U.S./Russia Agreement on Cooperation in Space Exploration was signed [1]. NASA
and Hamilton Standard (HS. now Hamilton Sundstrand) showed interest in Zvezda's
experience in the development and operation of orbit-based EVA suits. That year,
ESA and Roscosmos separately agreed to Initiate a requirements analysis and con-
(eptual design study to determine the feasibility of joint spacesuit developillent- the
EVA 2000 [1]. WThen the Space Station Freedom (SSF) became the ISS and was
expanded to include Roscosnos, ESA and Roscosnos pushed for U.S. support on a
joint development of a new spacesuit based o1 the EVA Suit 2000 to become the
one and only spacesuit system on the ISS [20]. Not only is it expensive to develop
and prototype a new EVA system. but to do so while incorporating the different
design philosophies and their contractors can seem insurmountable: it is clearly not
cost effective [7]. Moreover, the EMU was already too far along for them to consider
63
it. The EVA suit 2000 program eventually also faltered due to financial difficulties
[20]. There have been several other contracts between Roscosmos and NASX: com-
parative analysis of US and Russian EVA suits (Figure 5-2), feasibility of bringing
them together, provision for EVA in the Russian suit undertaken from the US air-
lock, development of means for unassisted rescue of ISS crew members during EVA
(SAFER), training U.S. specialists in Orlan operations, and training US astronauts in
wearing Russian EVA suits [1]. One of the only successful joint suit-system programs
between NASA and Roscosmos is the development of the Russian Simplified Aid for
EVA Rescue (SAFER). It was initially developed in the U.S. as an element of the
EMU so that should the primary crewmember-to-station restraint tether fail, there
would be a backup means of retrieving the crewmember since the ISS could not ma-
neuver for rescue [20]. Since 1997, astronauts and cosmonauts have used Russian and
U.S. made spacesuit systems interchangeably and with increasing frequency, however,
mission operations planning and training would become significantly easier with the
design of one single spacesuit for all future joint missions.
According to Harris, NASA and Roscosmos had (and still currently have) three
choices in interfacing their divergent spacesuit systems:
1. an expensive "clean sheet" approach, giving up the current agency specific de-
velopment (then the Shuttle EMU/Orlan) and building a whole new suit,
2. symbiosis by joining the two suit systems with as many interchangeable com-
ponents and operational methods as possible,
3. or, a level of interoperability that would cover efforts to find a minimal interface
while actually changing their respective systems little [7].
The third option has been somewhat accomplished since Harris published his book
in 2001 with the introduction of the ISS Quest Airlock. The second option seems
more reasonable than starting with a clean sheet and building a whole new spacesuit,
however, a cost analysis would be in order to determine whether option two would be
that much more cost efficient than option when merging major suit incompatibilities.
64
However, if we want to continue to expand beyond LEO, into planetary EVA, it is
imperative to build (or modify) a spacesuit as a collaboration between all relevant
agencies.
65
Chapter 6
Conclusions
Extravehicular activity is perhaps the most rewarding and complex aspect of human
spaceflight. Perhaps in the near future, EVA will be performed outside of low-Earth
orbit on the surface of Mars. There are still major EVA suit design challenges to
overcome, as well as challenges in standardization for streamlined international coop-
eration. Additionally, there are major physiological and technical challenges humans
will need to overcome in order to accomplish successful long-duration flight missions.
The contributions of this research are:
1. 'an increased understanding of the human-spacesuit interaction specifically at
the shoulder interface: while pressure magnitude can vary based on anthro-
pometric measurements, it can be confirmed that pressure magnitudes at the
top of the shoulder must be addressed with protective measures and in future
design.
2. While the Novel sensor system proves to be state-of-the-art pressure sensing
equipment, a network of smaller, variably placed sensors may be a preferred
means of analyzing the human shoulder interface for clearer data.
3. With the future pressure sensing design improvements mentioned above, this
method of measuring contact pressures can and should be expanded to protec-
tive wear and other applications.
66
4. There have been attempts to incorporate EVA capabilities among space agen-
cies, but a stronger push is necessary between U.S. and Russia for complete
equipment standardization.
With regard to the EVA human-shoulder interface experiment, further studies
should integrate the spacesuit pressure and joint angle data found in other work with
metabolic data in order to understand how fatigue and injury influence the metabolic
work necessary for space operations. With regard to policy and standardization in
EVA operations, NASA and Roscosmos should reevaluate current suit development
projects and attempt to consolidate projects to develop a joint spacesuit program
such as the EVA 2000 program. Each of the specific aims addressed in this thesis
provides a different suggestion for approaching the issues currently present in EVA. It
is imperative that these issues be overcome if we plan to continue toward the ultimate
goal of human planetary exploration.
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Appendix A
Human-Suit Interface Pressure
Evaluation
68
Human-Suit Interface Pressure Evaluation
MIT Man Vehicle Lab & David Clark Company
Prepared by Pierre Bertrand, Alexandra Hilbert, Sabrina Reyes, MIT
1 IntroductionThe objective of this research is to develop an understanding of how the person interacts with the
space suit, and use that information to assess and mitigate injury. Our approach is to quantify and
evaluate human-space suit interaction with a pressure sensing tool, focusing on the arm and
shoulders under different loading regimes. Additionally, inertial measurement units (IMUs) will be
placed both internal and external to the space suit arm to assess biomechanics. This portion of the
study builds from previous collaboration between the MIT Man Vehicle Lab and the David Clark
Company. Informal objectives include evaluating the feasibility of a synchronized pressure sensing
as a platform used inside the space suit. MIT has developed a prototype platform, consisting of
custom and off-the-shelf sensors and an integrated data acquisition system, all incorporated into a
modified athletic garment, capable of sensing pressure at various locations along the arm and
shoulder. Establishing a precedent and proof of concept for this methodology will open the
doorway for future collaboration and technology development.
2 Test SummaryOne subject, two, time permitting, will be asked to perform the test protocol in the Boeing space
suit. Subjects will be selected based on availability from David Clark personnel who meet the
medical requirements for in-suit testing. These individuals have a great deal of experience working
inside the space suit so will not have to develop new, potentially confounding movement strategies.
The subjects will be wearing the pressure sensing and IMU systems while performing the tests, and
pressure profiles and angle histories will be recorded. The test protocol will consist of 20
repetitions of 4 motions inside the space suit. The selected movements use the upper body where
the sensors are placed. The 5 motions are 3 isolated joint movements (Elbow flexion/extension,
Shoulder flexion/extension, and Shoulder abduction/adduction) and 1 functional task (Cross Body
Reach). Prior to the test, subjects will be trained on each movement and allowed to repeat it as
many times as they desire. For each movement, the 20 repetitions will be further subdivided into 4
groups of 5 repetitions each. This is done to evaluate subject fatigue or potential change of
biomechanical strategies over the course of the test period. After each group of movements,
qualitative information on subject comfort and hot spots will be collected. The information will also
be collected after training. Each of these test conditions will be counterbalanced and randomized.
69
3 MIT HardwareThe human-suit interface is currently an unknown in space suit characterization. Pressuremeasurements would allow greater insight into how these interactions occur and help characterize
suit performance. Additionally it would allow us to prevent injury incurred by motion inside the
suit. There is currently no method by which to characterize this pressure. The two systems selectedto measure pressure are targeted at different pressure sensing regimes.
The pressure sensing system is integrated into one conformal athletic garment. Both pressure
sensor systems are mounted to the shirt as described below. Finally, a cover shirt slides easily overthe sensors to prevent catching and ensure proper sensor placement.
3.1 Novel Pressure Sensing SystemThe garment has a pocket interface over the shoulder to house the Novel pressure sensor, which is
used for the high-pressure sensing regime. The high pressure regime is at the interface between the
person's body and the hard upper torso of the suit. A Novel pressure sensing mat has been usedpreviously in a study by the Anthropometry and Biomechanics Facility (ABF) on an Extravehicular
Mobility Unit hard upper torso.
e One commercially available Novel pressure mat, S2073 with 128 sensors
" Each sensor is 1.4cm in each dimension and pressure range between 20-600kPa
* Mat slips into pocket over shoulder
e On-board data collection with electronics mounted at the base of the back
* Similar system used inside the extravehicular mobility unit by the Anthropometry andBiomechanics Facility without modification for a shoulder load study
* Sensor runs at 330mA currente Battery is 10 1.2V nickel metal hydride
The system is certified to the European safety standard 93/42/EEC (Annex 1X).* Due to the construction of the battery it is unlikely that water or sweat will come into
contact with the electronics board of the battery pack. It is also unlikely that a smallamount of moisture would create an electrical shortcut.
* The pedar NiMH 2000mAh battery pack is internally secured with an overheating andan overcurrent protection (Polyswitch).
* Worst case scenario for puncture: On the transmitter side of the sensor mats a voltageof 7 V (effective) = equal to 20 Vpp is applied (pp = peak to peak). The maximumcurrent for a shortcut is 100 mA(pp) if one directly touches the transmitter. Fortechnical applications the resistance of the human body is typically considered to be 1 -2.4 kOhm. In that case the maximum current would be 8 - 20 mA(pp).
70
Figure 2: Novel Pressure sensing system. A) Sensor mat. B) Data acquisition and battery
3.2 Polipo Pressure Sensing SystemThis shirt is worn by the subject and has targets over which the low pressure sensors are mounted.
The Polipo, or octopus in Italian, is the system of 12 sensors which were developed as part of this
research effort for low-pressure sensing under the soft goods. These sensors are placed over the
arm in a way that targets anticipated hot spots, and secondarily for uniform coverage. The sensors
are detachable from the athletic garment, allowing independent pressure sensing system. It also
allows for shifting the sensors to concentrate them over a certain region of the body.
- 12 developmental sensors distributed over the arm
* Detachable system transferrable between subjects with velcro
e On-board data collection with electronics mounted at the base of the back
- Each sensor powered with constant current of.5mA
o Microcontroller shown; new board will be fabricated (not shown)
0 The entire board in nominal operation with 12 sensors is estimated to be around 100mA
- Battery selection is TBD but at the moment may be an off the shelf 9V battery. A typical 9V has
about 500mAh, so we are estimated to have 4 hours of use
- Shorting the sensor wires of one circuit will result in -. 5mA through the short
- A sensor short through the sink wire of another sensor will result in -1.1mA
- Worst case scenario would short the sink wire of all 12 circuits giving -6mA. This is highly
unlikely
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Figure 2: Polipo pressure sensing system. A) Sensors mounted on sleeve. B) Microcontroller.
Arduino shield not shown
3.3 APDM IMU Sensing SystemAdditional information about the human-suit interface may be gathered using IMU data collected
inside the space suit. There is a joint angle difference between the person's movement and that of
the space suit. This is due to the resistance of a gas pressurized suit to movement, as well as (in
some instances) anatomically inaccurate rotation due to bearing movement. Calculating the joint
angles measured internal and external to the suit would help elucidate these differences. Previous
studies performed by the ABF and researchers at the University of Maryland have evaluated the use
of IMUs inside a gas pressurized space suit. This experiment uses similar methods, mirroring a
previous study performed by our research group inside a gas pressurized suit at David Clark
Company. This data will be used not only to determine biomechanical differences but also to help
find points of maximum and minimum movement to analyze the pressure profiles. It will be
matched with video data to improve the results. Sensors will be placed on the lower and upper arm
of the subject, not in contact with the pressure sensors. An additional chest mounted IMU will serve
as a reference for shoulder rotation data. Three sensors will be placed external to the suit, two on
the upper and lower arm and one on the suit upper torso.
* Commercially available APDM Opal inertial measurement unit (IMU)- 3 internally mounted sensors on the upper and lower arm and chest- 3 externally mounted sensors: Upper and lower spacesuit arm and suit torso- Each is 4.8x3.6x1.3 cm (lxwxh) and weighs less than 22ge Lithium Ion battery at 3.7V nominal- The capacity found online is 450mAh. Assuming that it can last minimum 8h (as said in the
documentation), the current is max 56 mA. It's maximum is1.6 hours of operation, so the currentwould be 28mA
- The worst case scenario is venting of the battery. Safety precautions include aluminum base toprotect the person, battery protection circuit, safe charging features. Probability estimated at.000001
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The Opal movement monitor
Figure 4: Opal IMU sensor from APDM
4 Detailed Test PlanThis test will be performed by one subject or two if time permits. The following tasks will be
performed both suited (at pressures: 0.25 psi (venting), 2psi (intermediate pressure) and 3.5 psi
(full pressure)) and unsuited as described in the configurations above. The first time the task is
performed suited, each task will be repeated through 5 repetitions, whichever comes first. After
each of the 5 movements is performed, the subject will rest for 5 minutes and subjective data will
be collected. The subject will then repeat the movement sequence and rest period three additional
times.
Below are the tasks the subject will be performing in this test campaign.
Elbow Flexion/Extension
The subject stands away from the donning stand supported by their own effort. Beginning with
both arms relaxed at their side, palms facing anterior, the subject bends the arms at the elbow
through their maximum range of motion. The subject then releases to the relaxed position.
ShoulderFlexion/Extension
The subject stands away from the donning stand supported by their own effort. Beginning with
both arms relaxed at their side, the subject bends the arms at the shoulder through the sagittal
plane. The subject moves through their maximum range of motion. The subject then releases to the
relaxed position.
Shoulder Abduction/Adduction
The subject stands away from the donning stand supported by their own effort. Beginning with
both arms relaxed at their side, the subject bends the arms at the shoulder through the coronal
plane. The subject moves through his or her maximum range of motion. The subject then releases to
the relaxed position.
Cross Body Reach
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The subject stands away from the donning stand supported by their own effort. Beginning with
both arms relaxed at their side, the subject will reach across their body in an attempt to touch their
hip on the opposite side. The subject will then move their arm up to chest level and sweep their arm
in front of their body in the horizontal plane. When the arm is extended straight in front of the
shoulder, the subject will then attempt to touch the helmet at the position of their ear on the same
side. The movement is then repeated with the opposite arm.
Table 1 shows a summary of all functional tasks each run will consist of, and a cumulative time for
the run as currently scheduled. Each subject will perform these tasks in the order specified.
DescriptionMinute
MinCCount
Elbow
Flexion/Extension
Shoulder
Flexion/Extension
Shoulder
Abduction/Adduction
Cross Body Reach
Rest
Isolated Stand free of donning stand and bend elbow
Isolated Stand free of donning stand and bend shoulder
Isolated Stand free of donning stand and bend shoulder
1.30 1.30
1.30 3
1.30 4.30
Stand free of donning stand and reach fromFunctional 2.30 7
overhead across the body, alternating arms
Rest mounted in donning stand. Qualitative
Information collected12
Table 1: Test variables matrix
Each of the subjects will perform this series of tasks identified in Table 1 four different ways:
1. Unsuited2.3.4.
Suited at 0.25 psi (venting pressure) in the Boeing suit
Suited at 2 psi (intermediate pressure) in the Boeing suit
Suited at 3.5 psi (full pressure) in the Boeing suit
The order of these tasks will vary between subjects, but the matched-pace unsuited run will always
be completed last. In addition, some familiarization time is built into the test plan for each suit to
allow the subject to become comfortable performing each task in the suit he or she has just donned.
Not only will this make the subject more comfortable and safe while performing the tasks, but it
will also reduce the possibility of familiarization of a task negatively affecting the outcome of the
test
This test may be terminated by the subject at any time for any reason, or by the test conductor, suit
technicians or suit engineer due to any safety or hardware concerns or concern for the suited
subject. Between movement groups, subjective data will be taken from the subject. This will be
74
Task Type
used as an indicator of subject fatigue and desire to terminate the test. An outline of the questions
to be asked is shown in Appendix A.
The test will also be terminated in the event of unrecoverable suit system failure. Standard David
Clark procedures will be followed regarding the failure of any suit system part, or any suit
emergency.
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5 Procedures
5.1 Test-Specific Pre-Test Safety Briefing
1. Anyone can stop this test at any time for any reason
2. Test personnel: Manage video camera, extension cords and functional task props at all times.
3. Suited Subject: We will ask you how you're feeling between each task, absent any other reportsfrom you. After each series of 5 tasks, which will last approximately 2 minutes each for a total of10 minutes, you will rest for at least 5 minutes.
5.2 Detailed Test Procedure
1. Initial IMU calibration
2. Review summary of test with subject
3. Conduct test-specific pre-test safety briefing
4. -Synchronization process
a. Close Motion Studiob. Connect IMUs and Novel system through sync boxc. Turn on Novel and sync boxd. Open Motion Studio with appropriate settingse. Initiate MATLAB timer toolf. Trigger the synchronization and begin the timerg. Unplug synchronization cables
5. -Test personnel places IMUs on the subject and notes location on the body
6. Subject dons pressure sensing systems
7. Polipo is turned on
8. Cover shirt is donned
9. -Body marks are pressed (1-acromion, 2-clavicle, 3-shoulder blade)
Unsuited Test
Unsuited Calibration
10. Subject perform wrist pronation/supination 90 degrees (2 times)
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11. Subject perform elbow flexion/extension 90 degrees (2 times)
12. Subject perform shoulder flexion/extension 90 degrees (2 times)
13. Subject perform shoulder abduction/adduction 90 degrees (2 times)
Unsuited Familiarization Session
14. Subject practices elbow flexion/extension
15. Subject practices shoulder flexion/extension
16. Subject practices shoulder abduction/adduction
17. Subject practices cross body reach task
Unsuited Data Collection Run
18. Subject performs 1st movement group
a. Allow subject to rest while prompting for subjective feedback
19. Subject performs 2nd movement group
a. Allow subject to rest while prompting for subjective feedback
20. Subject performs 3rd movement group
a. Allow subject to rest while prompting for subjective feedback
21. Body marks are pressed (1-acromion, 2-clavicle, 3-shoulder blade)
Suited Tests
22. Subject dons suit
23. Suit pressurized to venting pressure
24. Test personnel places IMUs on the space suit's arm and notes location (anthropometrics)
25. Suit technicians assist subject in moving from donning stand to functional task area
Suited Venting Pressure Test
NOTE: The subject completes 5 repetitions of the task. Time is not limited, but the task may be
terminated if the subject is unable to complete 5 repetitions.
NOTE: Instruct subject to complete these tasks at what they consider to be a natural pace
77
NOTE: Request a report of any symptoms from suited subject after each task and ask qualitative
questions from Appendix B during the 5-minute rest periods.
NOTE: Five minute break (minimum) is enforced between each group of movement tasks. Allow suited
subject to take additional rest time as needed.
NOTE: Subject task order is counterbalanced for each subject and each movement run. The task order is
provided in Appendix A.
NOTE: Subject may return to donning stand for rest if necessary at any point
Suited Venting Calibration
26. Subject perform wrist pronation/supination 90 degrees (2 times)
27. Subject perform elbow flexion/extension 90 degrees (2 times)
28. Subject perform shoulder flexion/extension 90 degrees (2 times)
29. Subject perform shoulder abduction/adduction 90 degrees (2 times)
Suited Familiarization Session
30. Subject practices elbow flexion/extension
31. Subject practices shoulder flexion/extension
32. Subject practices shoulder abduction/adduction
33. Subject practices cross body reach task
34. Subject returns to donning stand for rest (at least two minutes)
Suited Venting Pressure Data Collection Run
35. Subject performs 1st movement group
a. Allow subject to rest while prompting for subjective feedback
36. Subject performs 2nd movement group
a. Allow subject to rest while prompting for subjective feedback
37. Subject performs 3rd movement group
a. Allow subject to rest while prompting for subjective feedback
38. Suit technicians assist subject in moving back to donning stand
Suited Intermediate Pressure Test
78
39. Suit pressurized to intermediate pressure (2 psi)
40. Suit technicians assist subject in moving from donning stand to functional task area
Suited Intermediate Pressure Calibration
41. Subject perform wrist pronation/supination 90 degrees (2 times)
42. Subject perform elbow flexion/extension 90 degrees (2 times)
43. Subject perform shoulder flexion/extension 90 degrees (2 times)
44. Subject perform shoulder abduction/adduction 90 degrees (2 times)
Suited Intermediate Pressure Data Collection Run
45. Subject performs 1st movement group
a. Allow subject to rest while prompting for subjective feedback
46. Subject performs 2nd movement group
a. Allow subject to rest while prompting for subjective feedback
47. Subject performs 3rd movement group
a. Allow subject to rest while prompting for subjective feedback
48. Suit technicians assist subject in moving back to donning stand
Suited Full Pressure Data Collection Run
49. Suit pressurized to full pressure
50. Suit technicians assist subject in moving from donning stand to functional task area
Suited Full Pressure Calibration
51. Subject perform wrist pronation/supination 90 degrees (2 times)
52. Subject perform elbow flexion/extension 90 degrees (2 times)
53. Subject perform shoulder flexion/extension 90 degrees (2 times)
54. Subject perform shoulder abduction/adduction 90 degrees (2 times)
Suited Full Pressure Calibration Data Collection Run
55. Subject performs 1st movement group
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a. Allow subject to rest while prompting for subjective feedback
56. Subject performs 2nd movement group
a. Allow subject to rest while prompting for subjective feedback
57. -Subject performs 3rd movement group
a. Allow subject to rest while prompting for subjective feedback
58. Suit technicians assist subject in moving back to donning stand
Post-Test Procedures
59. External IMUs removed from suit
60. Depressurization of suit and suit doffed
61. Subject remains in LCVG with pressure sensors and IMUs in place
62. Body marks on the shoulder are recorded (1-acromion, 2-clavicle, 3-shoulder blade)
63. Subject debrief (any final subjective feedback)
80
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