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- Title
G Tolerance During Open- vs. Closed-Loop G-Time Control.
- Authors
Gronkvist, Mikael; Levin, Britta; Eiken, Ola
- Abstract
BACKGROUND: +Gz tolerance is traditionally determined in centrifuges w th 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 o f +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 w ith visual feedback; 2) OL-NFB, open loop w ith no visual feedback; and 3) CL, closed loop. Straining +Gz tolerance was determined in 10 men during ROR in OLand 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.
- Subjects
MARITIME pilots; CENTRIFUGES
- Publication
Aerospace Medicine & Human Performance, 2018, Vol 89, Issue 9, p798
- ISSN
2375-6314
- Publication type
Article
- DOI
10.3357/AMHP.5096.2018