The comparison of vestibular illusions and vestibular autonomic reactions induced by various speed short arm centrifuge operation

Abstract

Objective To observe the effects and characteristics of vestibular illusions and vestibular autonomic reactions induced by short arm centrifuge exposure,and to search the appropriate rotation speed of short arm centrifuge for vestibular illusion simulation training on the ground.Methods Ninety healthy pilots were divided into 3 groups by the rotation speed of 21,30 and 37 r/min that generated by SAC-Ⅲ short arm centrifuge.By referencing the vestibular illusions simulation training on electric rotating chair,they were exposure to the simulation of counter-rotatory illusion and Coriolis illusion.Vestibular illusions and vestibular autonomic reactions were compared.Results ①When the speed was 21 r/min,the induced rates of the counter-rotatory illusion,Coriolis tumbling illusion (including head turn to right and to left) and Coriolis somatogyral illusion (including head pitched up and down) were lower than the induced rates under the speed of 30 r/min and 37 r/min (X2＝6.477 20.000,P＜0.01 or P＜0.05).And when the speed was 30 r/min and 37 r/min,the induced rates showed no significant difference (x2 ＝0.073-0.351,P＞0.05).②The expressions and characteristics of the centrifuge evoked counter-rotatory illusion were approximately the same under three different rotation speeds,while the illusion strength was enhanced with the speed increase.The expressions and characteristics of the Coriolis tumbling illusion induced by different speed showed no significant difference (X2 ＝0.090,0.056,P＞0.05).And the expressions of the Coriolis somatogyral illusions were multiform.Under three different speeds,the Coriolis somatogyral illusions showed no significant difference when the pilot's head pitched down (X2 ＝ 1.810,P＞0.05).The case of Coriolis somatogyral illusions was very rare when pilot's head pitched up and the result was not taken into account.③The scores of vestibular autonomic reaction were increased with the rotation speed increase,and showed significant difference (F＝ 15.058,P＜0.01).When the speed was 37 r/min,the score of vestibular autonomic reaction was significantly higher than the scores of 21 r/min and 30 r/min (P＜0.01 or P＜0.05),and there was no significant difference between the scores of 21 r/min and 30 r/min (P＞0.05).Conclusions When the speed of centrifuge was 30 r/m in,the induced rate of the vestibular illusions was the highest and the vestibular autonomic reaction was mild.For the 2 m arm centrifuge,the 30 r/min rotation was appropriate for pilots' vestibular illusion simulation training on the ground. Key words: Centrifugation;  Illusion;  Vestibule;  Coriolis force