Effect of radius versus rotation speed in artificial gravity.

Artificial gravity by centrifugation can lead to perceptual disturbances in the form of motion sickness and/or misperception of motion during head movements, but the degree of perceptual disturbance during centrifugation in 0-g has not been thoroughly investigated. It is known that during whole-body on-axis yaw rotation in 0-g, head movements in pitch and roll cause very little disturbance, despite significant disturbance in 1-g. Therefore, 1-g experimental results do not apply directly to 0-g without further analysis. A modeling approach was used here to predict disorienting effects in 0-g and 1-g environments, with different rotation speeds, centrifuge radii, and directions of head movement. The results were based upon investigation of the stimulus itself, in the form of angular and linear accelerations, and their consequences due to linear-angular interactions in three dimensions. The results explain known differences in 0-g and 1-g, for head turns toward and away from the direction of motion, and for head movements on- and off-axis. Additional predictions include an increase in perceptual disturbance with the magnitude of the gravito-inertial acceleration (GIA), therefore an increase off-axis, but a decrease in 0-g. Also predicted is that head-movement direction makes a difference, with rotation outward relative to the centrifuge axis causing the least disturbance.