The Anthropometry and Biomechanics Laboratory (ABL) at JSC conducts multi-disciplinary research focusing on maximizing astronaut intravehicular (IVA) and extravehicular (EVA) capabilities to provide the most effective work conditions for manned space flight and exploration missions. Biomechanics involves the measurement and modeling of the strength characteristics of the human body. Current research for the Space Shuttle Program includes the measurement of torque wrench capability during weightlessness, optimization of foot restraint, and hand hold placement, measurements of the strength and dexterity of the pressure gloved hand to improve glove design, quantification of the ability to move and manipulate heavy masses (6672 N or 1500 lb) in weightlessness, and verification of the capability of EVA crewmembers to perform Hubble Space Telescope repair tasks. Anthropometry is the measurement and modeling of the dimensions of the human body. Current research for the Space Shuttle Program includes the measurement of 14 anthropometric parameters of every astronaut candidate, identification of EVA finger entrapment hazards by measuring the dimensions of the gloved hand, definition of flight deck reach envelopes during launch and landing accelerations, and measurement of anthropometric design parameters for the recumbent seat system required for the Shuttle/Mir mission (STS-71, Spacelab M) scheduled for Jun. 1995

Klute, Glenn K.

Stoycos, Lara E.

English

NASA Technical Reports Server

N94. 33629
An Overview of Space Shuttle Anthropometry and Biomechanics Research
with Emphasis on STS/Mir Recumbent Seat System Design
Glenn K. Klute
NASA JSC
Houston, TX 77058
Lara E. Stoycos
Lockheed Engineering and Sciences Co.
Houston, TX 77058
ABSTRACT
The Anthropometry and Biomechanics Laboratory (ABL) at the Johnson Space Center conducts
multi-disciplinary research focusing on maximizing astronaut intravehicular (IVA) and
extravehicular (EVA) capabilities to provide the most effective work conditions for manned
space flight and exploration missions. Biomechanics involves the measurement and modeling
of the strength characteristics of the human body. Current research for the Space Shuttle
Program includes the measurement of torque wrench capability during weightlessness,
optimization of foot restraint and hand hold placement, measurement of the strength and
dexterity of the pressure gloved hand to improve glove design, quantification of the ability to
move and manipulate heavy masses ( 6672 N or 1500 lb) in weightlessness, and verification of
the capability of EVA crewmembers to perform Hubble Space Telescope repair tasks.
Anthropometry is the measurement and modeling of the dimensions of the human body. Current
research for the Space Shuttle Program includes the measurement of 14 anthropometric
parameters of every astronaut candidate, identification of EVA finger entrapment hazards by
measuring the dimensions of the gloved hand, definition of flight deck reach envelopes during
launch and landing accelerations, and measurement of anthropometric design parameters for
the recumbent seat system required for the Shuttle/Mir mission (STS-71, Spacelab M)
scheduled for June 1995.
INTRODUCTION
The Anthropometry and Biomechanics Laboratory (ABL) at the Johnson Space Center conducts
multi-disciplinary research focusing on maximizing astronaut intravehicular activities (WA)
and extravehicular activities (EVA) capabilities. This research is conducted to provide the
most effective work conditions for manned space flight and exploration missions. The ABL
performs research in two areas: anthropometry and biomechanics. Biomechanics is the
measurement and modeling of the strength characteristics of the human body, while
anthropometry is the measurement and modeling of the dimensions of the human body. An
overview of the current research directions will be presented along with an example
(Shuttle/Mir recumbent seat system design) of the how the human factors product is used in
practice.
BIOMECHANICS
In altered-gravity environments, such as the "weightlessness" of low earth orbib crew
capabilities are dramatically different from what they are in the one-gravity environment on
Earth. The ABL performs tests to measure and model human strength capabilities in
weightlessness. In addition to the laboratory itself, several different simulation facilities are
used to conduct investigations. These facilities include the Precision Air Bearing Floor and the
Weightless Environment Training Facility at the Johnson Space Center, as well as the KC-135
zero-gravity research aircraft based at Ellington Field, Houston, TX.
A recent test was conducted on the KC-135 to measure torque wrench capabilities of subjects
while in prototype intravehicular activity (IVA) foot restraints 1. The KC-135 provides brief
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periods of zero-gravity (25 to 30 seconds) while flying parabolic profiles. The test set-up
utilized a prototype foot restraint with an adjustable pitch angle. The test subject, wearing
socks, was allowed to adjust a 3.8 cm (1.5 in) wide foot loop to a comfortable tension. The subject
was then directed to apply torques to an instrumented task board with a torque wrench. Instead
of torque, the applied forces were reported, allowing the designer or mission planner to select
the appropriate tool length required to generate the necessary torque to complete the task. The
forces measured were highly dependent on the direction of effort. When applying force in an up
or down direction, the subject was able to position his/her body to use the large muscle masses in
the legs to generate large forces. These forces were on the order of 467 N (105 lb) in the down
direction and approximately 663 N (140 lb) in the up direction. Forces to the left and right of
the subject averaged about 356 N (80 lb) to the left and 400 N (90 lb) to the right, while forces
toward (such as pulling an object) and away (such as pushing an object) were about 289 N (65 lb)
towards and 356 N (80 lb) away, respectively.
In addition to tasks requiring strength inside the crew compartment of the Shuttle,
crewmembers must perform numerous physical tasks while EVA. Occasionally, portable foot
restraints are not available to react applied forces and torques. In this situation, crewmembers
must use only one hand to counteract the forces and torques of the tool hand. During another
study carried out on the KC-135 in which EVA suited subjects applied torques with a 25 cm (10
in) tool handle and used only a single hand restraint, the torques measured were on the order of
70 to 80 N-m (52 to 59 ft-lb) in zero-gravity 2.
One of the keys to a successful EVA is adequate hand function. The hand serves as a multi-
purpose end effector required to perform a variety of tasks ranging from holding on to free
floating satellites to using EVA tools. Measurements of grasp breakaway forces, which
simulate holding a satellite by hand with an EVA handrail, found crewmembers capable of
exerting grasp forces in excess of 1000 N (225 Ib) 3. Results from the hand grasp breakaway test
indicated that the right hand is generally stronger than the left, and female grip strength is
typically 50 percent of male grip strength. Further tests, evaluating barehanded versus gloved
hand performance, found the following results: wearing an EVA glove reduces grip capability
by 50 percent regardless of gender, performance decreases with increasing pressure, and pinch
strength is unaffected by wearing an EVA glove 4.
Manipulation of large masses is another task often required of the crewmember. This task is
required in the IVA environment due to the need to move instrumentation racks about the crew
compartment on Space Station Freedom. To measure the forces and torques required when
manipulating a Space Station IVA rack, a test was conducted on the Precision Air Bearing Floor
at Johnson Space Center 5. This test used a heavy rack mock-up weighing 6672 N (1500 Ib) with
an instrumented handrail. The results indicated forces of less than 11 N (8 lb) and torques of
less than 3.4 N-m (2.5 ft-lb) were required to manipulate the rack.
Manipulating large masses is also required in the EVA environment. Manual handling of the
Intelsat satellite (STS-49, June 1992) was required to successful capture the satellite. Large
mass handling will also be required on the Hubble Space Telescope Service Mission 01 (STS-61,
December 1993). Significant operational concerns are inherent with EVA mass handling tasks.
Of critical importance to insure safety of the crewmember as well as the integrity of the
payload, is to verify that the tasks required are within the crewmember's capability. A mass
handling test, which used a mock-up of one of the Hubble's instruments scheduled for
replacement, with correct mass and inertia properties, was conducted on the Precision Air
Bearing Floor 6. This test measured the forces and torques required to maintain stable control of
the orbital replacement unit (ORU) while performing insertion tasks and operations with the
remote manipulator system (RMS). The results found that the amount of force that can be
expected during ORU insertion tasks varied from about 18 N to 62 N (4 Ib to 14 lb) while the
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torques varied from 11 N-m to 20 N-m (8 ft-lb to 15 ft-lb). During the RMS operations, the
worst case force at the handrail was approximately 222 N (50 lb) during a sudden stop of the
RMS when translating at 0.5 m/s (1.5 ft/sec). This test verified that the forces and torques
required to perform the task were well within the crewmember's capabilities.
ANTHROPOMETRY
Anthropometry is the measurement and modeling of the dimensions of the human body and
includes both static and dynamic measurements. Anthropometric data can be used to size
pressure garments, EVA gloves, and flight clothing so appropriate tariffs can be developed to
accommodate all crewmembers. Other uses include developing hardware such as exercise
equipment, EVA and IVA tools, crew seats, and flight control systems.
The ABL maintains a database of anthropometric measurements from astronauts and astronaut
applicants. As part of the astronaut selection process, the ABL measures 14 anthropometric
variables from each astronaut applicant. Recently, statistical analyses were performed on the
database created over the data collection period from 1985 to 19917 . This period includes 473
individuals, 82 of which were selected as astronauts.
An operational concern involving anthropometry during EVA includes the risk of finger
entrapment. The potential for such a situation would be a serious safety problem. The ABL
conducted a glove box test with series 3000 gloves at 0.624 kPA (4.3 psi) to determine the range
of hole sizes that could result in finger entrapment 8. Based on experimental results, the
smallest diameter should be less than 13 mm (0.50 in) and the largest diameter should be
greater than 35 mm (1.38 in) in order to eliminate the possibility of finger entrapment during
EVA.
Anthropometry is typically static, that is there is no motion. However, certain conditions can
require the measurement of anthropometry under dynamic conditions. An example of this is a
crewmember's reach envelope and how it changes under various gravitational conditions 9.
Launch profiles create accelerations on the order of three times that of Earth's gravity (3 g's).
Certainly, the reach envelope of a crewmember on the flight deck during launch will be
different than that experienced in I g. Measurement of reach envelopes under various
acceleration environments provide designers with the information needed to properly design
flight systems which are accessible under flight conditions.
SHUTTLE/MIR RECUMBENT SEAT SYSTEM
Anthropometry is used frequently to design equipment and flight hardware. An example of
this process is the anthropometric data required to design the seating system for the
Shuttle/Mir mission.
In June of 1995, the Space Shuttle (STS-71, Spacelab-M mission) will rendezvous and dock with
the Russian space station Mir 10. The Space Shuttle will return to a landing site in the U. S.
with three crewmembers: a Russian trained U.S. astronaut and two cosmonauts. The primary
U. S. scientific goals are to investigate the effects of long-duration space flight on the human
body. One of the operational concerns is the level to which the returning Mir crewmembers will
be able to withstand the g conditions during the return flight. Because the long stay aboard Mir
will cause cardiovascular deconditioning and muscle atrophy, it was proposed that the crew
return to Earth in a recumbent position to minimize the effects of these physiological changes.
Returning the crewmembers in a recumbent position requires the design of a new seating system.
However, the existing anthropometric data for seat systems is based on measurements taken
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while the subjects were unsuited and sitting 11. To insure accuracy, the anthropometric data
must be collected when the subjects are wearing a pressurized Launch and Entry Suit CLES) and
are lying in a recumbent position.
Additionally, the design of the recumbent seating system must meet the requirements of both
5th percentile Japanese female and 95th percentile American male crewmembers. To
accommodate this requirement, a test was conducted where the subjects were measured in the
shirtsleeve condition, and then again after donning and pressuring the LES 12. To account for the
spinal elongation which occurs due to the absence of gravity, an additional three percent was
added to the spinal measurements 11. The difference between shirtsleeve and suited
measurements, which is representative of the change due to the suit, posture, and pressure can
then be added to the existing Man-Systems Integration Standards (MSIS) (NASA-STD-3000)
anthropometric data to project the measurements for 5th percentile Japanese female and 95th
percentile American male crewmembers 11.
ff,O2LC.LUSID_
Anthropometry and biomechanics research makes up an important component of a successful
manned space flight program. The environment of space, so unlike that here on Earth, often
requires performance tests in simulation facilities to measure crewmember capabilities.
Interaction with mission planners, hardware designers, astronauts, and others is essential in
creating a useful human factors product.
Wilmington, R. P., Poliner, J., and Klute, G. K., "Force Loading and Pitch Angle
Evaluations of an IVA Foot Restraint Design for Torque Wrench Tasks," NASA
Technical Memorandum in preparation, April 1993.
2 Poliner, J. and Rajulu, S., "Loads Produced by a Suited Operator performing Tool Tasks
without the Use of Foot Restraints," The Proceedings of the 64th Annual Scientific
Meeting of the Aerospace Medical Association, Toronto, Canada, May 1993.
3 Rajulu, S., and Klute, G. K., "A Comparison of Hand Grasp Breakaway Strength and
Bare-Handed Grip Strength of the Astronauts, SML III Test Subjects, and Subjects from
the General Population," NASA Technical Paper 3286, January 1993.
4 Bishu, R. R., Klute, G. K., and Byungjoon Kim, "Investigation of the Effects of
Extravehicular Activity Gloves on Performance," In Advances in Industrial Ergonomics
and Safety V. edited by R. Nielsen and K. Jorgensen, Taylor & Francis, 1993.
5 Stoycos, L. and Klute, G. K., "An Analysis of the Loads Applied to a Heavy Space
Station Station Rack During Translation and Rotation Tasks," In preparation for
publication as a NASA Technical Memorandum, August 1993.
6 Rajulu, S. and Klute, G. K., "Evaluation of COSTAR Mass Handling Characteristics in
a Friction-less Environment - A Simulation of the Hubble Space Telescope Service
Mission", In preparation for publication as a NASA Technical Memorandum, August
1993.
7 Rajulu, S. and Klute, G. K., "Anthropometric Survey of the Astronaut Candidates From
1985 to 1991," NASA Reference Publication 1304, May 1993.
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10
11
12
Rajulu, S. L. and Klute, G. K., "Evaluation of Hole Sizes in Structures Requiring EVA
Services as a Means to Prevent Gloved-Hand Finger Entrapment, NASA Technical
Memorandum 104767, April 1993.
Bagian, J. P. and Schafer, L. E., "Comparison of Current Shuttle and Pre-Challenger
Flight Suit Reach Capability During Launch Accelerations," Proceedings of the
Aerospace Medical Association (ASMA) 62nd Annual Meeting, May 1991, Cinncinati,
OH.
"Shuttle-Mir Program Offers Additional Opportunity to Examine Microgravity Effects
on Physiology," NASA Space Life Sciences Newsletter, Volume 1, Issue 3, Spring 1993,
pp. 9-10.
Man-Systems Integration Standards (MSIS), NASA-STD-3000, Volume 1, Chapter 3,
Revision A, October 1989.
Stoycos, L., Mongan, P. and Klute, G. K., "Anthropometry Data from Launch and Entry
Suited Test Subjects for the Design of a Recumbent Seating System," NASA Technical
Memorandum 26178, February 1993.
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An overview of Space Shuttle anthropometry and biomechanics research with emphasis on STS/Mir recumbent seat system design

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