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G Tolerance During Open- vs. Closed-Loop G-Time Control.
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Environmental Physiology. (Centrum för Flyg- och Rymdfysiologi, Swedish Aerospace Physiology Centre)
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Environmental Physiology. (Centrum för Flyg- och Rymdfysiologi, Swedish aerspace Physiology Centre)
2018 (English)In: Aerospace Medicine and Human Performance, ISSN 2375-6314, E-ISSN 2375-6322, Vol. 89, no 9, p. 798-804Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: +Gz tolerance is traditionally determined in centrifuges with open-loop G control, i.e., the centrifuge is under operator control (open loop), and thus the test subject is unable to influence the Gz load. In modern centrifuges, however, the subject is commonly able to continuously control the Gz load (closed loop). It is a widespread opinion among fighter pilots that +Gz tolerance is higher under closed- than open-loop G control. The aims were to investigate whether +Gz tolerance is higher in closed- than open-loop G control, and whether it is possible to use closed-loop G control during precise determination of +Gz tolerance.

METHODS: Relaxed +Gz tolerance was determined in eight men during rapid Gz-onset rate (ROR) under three conditions: 1) OL-VFB, open loop with visual feedback; 2) OL-NFB, open loop with no visual feedback; and 3) CL, closed loop. Straining +Gz tolerance was determined in 10 men during ROR in OL and CL conditions.

RESULTS: Relaxed +Gz tolerance did not differ between CL (3.66 Gz), OL-VFB (3.70 Gz) and OL-NFB (3.64 Gz). Straining +Gz tolerance was similar in the CL (8.5 Gz) and OL (8.6 Gz) conditions. In the CL condition, the Gz load varied substantially and was on average lower than in the OL conditions, at any stipulated G-time profile.

DISCUSSION: There is no systematic difference in relaxed or straining +Gz tolerance as determined in closed- vs. open-loop G-controlled systems. During closed-loop control, precision and reproducibility are too low to recommend it for accurate determination of relaxed G tolerance.Grönkvist M, Levin B, Eiken O. G tolerance during open- vs. closed-loop G-time control. Aerosp Med Hum Perform. 2018; 89(9):798-804.

Place, publisher, year, edition, pages
Ingenta , 2018. Vol. 89, no 9, p. 798-804
National Category
Medical and Health Sciences
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URN: urn:nbn:se:kth:diva-233529DOI: 10.3357/AMHP.5096.2018ISI: 000442351100004PubMedID: 30126512Scopus ID: 2-s2.0-85053263460OAI: oai:DiVA.org:kth-233529DiVA, id: diva2:1241198
Note

QC 20180903

Available from: 2018-08-22 Created: 2018-08-22 Last updated: 2020-03-09Bibliographically approved

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