NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Work and Fatigue Characteristics of Unsuited and Suited Humans During Isolated, Isokinetic Joint MotionsThe effects of a pressurized suit on human performance were investigated. The suit is known as an Extra-vehicular Mobility Unit (EMU) and is worn by astronauts while working outside of their space craft in low earth orbit. Isolated isokinetic joint torques of three female and three male subjects (all experienced users of the suit) were measured while working at 100% and 80% of their maximum voluntary torque (MVT). It was found that the average decrease in the total amount of work done when the subjects were wearing the EMU was 48% and 41% while working at 100% and 80% MVT, respectively. There is a clear relationship between the MVT and the time and amount of work done until fatigue. In general the stronger joints took longer to fatigue and did more work than the weaker joints. However, it is not clear which joints are most affected by the EMU suit in terms of the amount of work done. The average amount of total work done increased by 5.2% and 20.4% for the unsuited and suited cases, respectively, when the subject went from working at 100% to 80% MVT. Also, the average time to fatigue increased by 9.2% and 25.6% for the unsuited and suited cases, respectively, when the subjects went from working at 100% to 80% MVT. The EMU also decreased the joint range of motion. It was also found that the experimentally measured torque decay could be predicted by a logarithmic equation. The absolute average error in the predictions was found to be 18.3% and 18.9% for the unsuited and suited subject, respectively, working at 100% MVT, and 22.5% and 18.8% for the unsuited and suited subject, respectively, working at 80% MVT. These results could be very useful in the design of future EMU suits, and planning of Extra-Vehicular Activit). (EVA) for the upcoming International Space Station assembly operations.
Document ID
20030002666
Acquisition Source
Johnson Space Center
Document Type
Preprint (Draft being sent to journal)
Authors
Gonzalez, L. Javier (Johnson Engineering Corp. Houston, TX United States)
Maida, James C. (NASA Johnson Space Center Houston, TX United States)
Miles, Erica H. (Lockheed Engineering and Sciences Co. Houston, TX United States)
Rajulu, S. L. (National Space Biomedical Research Inst. Houston, TX United States)
Pandya, A. K. (Lockheed Engineering and Sciences Co. Houston, TX United States)
Russo, Dane M.
Date Acquired
August 21, 2013
Publication Date
January 1, 2001
Subject Category
Man/System Technology And Life Support
Report/Patent Number
JSC-CN-6412
Funding Number(s)
CONTRACT_GRANT: NRA-96-HEDS-05
Distribution Limits
Public
Copyright
Public Use Permitted.

Related Records

There are no records associated with this record.
No Preview Available