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Effect of Changing Weight and Mass on Human Performance in a Lunar Prototype SpacesuitPhysical effort, compensation, and controllability in a spacesuit can be affected by suit mass and gravity level. Because of limitations in certain reduced-gravity simulators and the finite selection of lunar prototype suits, it is difficult to ascertain how a change in suit mass affects suited human performance. One method of simulating a change in mass is to vary the total gravity-adjusted weight (TGAW), which is defined as the sum of the suit mass and subject mass, multiplied by the gravity level. PURPOSE: To determine if two methods of changing TGAW during parabolic flight - changing suit mass or gravity level - affect subjective ratings of suited human performance equally. METHODS: A custom weight support structure was connected to a lunar prototype spacesuit, allowing the addition of mass to the suit while maintaining a near-constant center of mass. In the varied-weight (VW) series, suit mass (120 kg) was constant at 0.1 G, 0.17 G, and 0.3 G, yielding TGAWs of 196, 333, and 588 N, assuming an 80-kg subject. In the varied-mass (VM) series, gravity level was constant at 0.17 G and suit mass was 89, 120, and 181 kg, yielding TGAWs of 282, 333, and 435 N. The 333 N condition was common to both series. Direct comparison was not possible due to limited adjustability of suit mass and limited options for parabolic profiles. Five astronaut subjects (80.3 11.8 kg) completed 4 different tasks (walk, bag pickup, lunge, and shoveling) in all conditions and provided ratings of perceived exertion (RPE) and the gravity compensation and performance scale (GCPS) upon completion of each task. RESULTS: Where VM and VW series overlapped, RPE and GCPS trendlines were similar. Mean RPE and GCPS at 333 N was 8.4 and 3.7. Mean RPE and GCPS for VM was 7.8 and 3.8 for 282 N and 9.8 and 4.1 for 435 N. Extrapolation of the VM trend to match VW TGAWs 196 and 588 N predicts an RPE of 6.5 and 12.3 and GCPS of 4.4 and 5.9, whereas the measured VW values for RPE were 8.1 and 9.8 and GCPS were 4.4 and 3.7. CONCLUSION: Modeling a change in suit mass by altering weight alone may be an adequate simulation through a limited range when looking at gross metrics of subjective suited human performance. Whether altering weight alone will be sufficient for more precise metrics of human performance, and across a wider range of activities, still needs further study.
Document ID
20090038960
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Norcross, Jason R.
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Chappell, Steven P.
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Gernhardt, Michael L.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2009
Subject Category
Life Sciences (General)
Report/Patent Number
JSC-CN-19240
Meeting Information
Meeting: American College of Sports Medicine (ACSM)
Location: Baltimore, MD
Country: United States
Start Date: June 2, 2010
End Date: June 5, 2010
Distribution Limits
Public
Copyright
Other

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