Colleen Butler1, Michael J Griffin. 1. Human Factors Research Unit, Institute of Sound and Vibration Research, University of Southampton, Southampton, England.
Abstract
BACKGROUND: The view ahead influences the motion sickness of car passengers but has been found to have little influence on the sickness caused by low frequency fore-and-aft oscillation. Acceleration and deceleration of vehicles is accompanied by pitch motions that may influence sickness. HYPOTHESES: It was hypothesized that: (1) a visual scene would influence sickness caused by combined fore-and-aft and pitch oscillation; and (2) sickness would be dependent on the phase between the fore-and-aft oscillation and the pitch oscillation. METHOD: While viewing one of three visual scenes (internal view, blindfold, or external view), 6 groups of 20 subjects were exposed for 30 min to 1 of 2 motions (in-phase or out-of-phase combinations of 0.1 Hz fore-and-aft and pitch oscillation). The 0.1-Hz fore-and-aft oscillation at +/- 1.26 ms(-2) rms (displacement of +/- 3.18 m) was combined with +/- 3.69 degrees pitch oscillation either in phase (so the pitch increased acceleration in the plane of the seat to +/- 1.89 ms(-2)) or out of phase (to reduce acceleration to +/- 0.63 ms(-2)). RESULTS: With both types of motion (in-phase and out-of-phase oscillation) there was significantly less sickness with an external view than with an internal view or a blindfold. There was evidence of an interaction between the effects of viewing condition and the effect of the phase between the fore-and-aft and the pitch oscillation consistent with blindfolded subjects experiencing less sickness when they experienced greater forces. CONCLUSIONS: Motion sickness caused by combined fore-and-aft and pitch oscillation depends on both the visual scene and the phase between the fore-and-aft and pitch motions. The minimization of sickness arising from such motions should involve the optimization of both the visual environment and the phase.
BACKGROUND: The view ahead influences the motion sickness of car passengers but has been found to have little influence on the sickness caused by low frequency fore-and-aft oscillation. Acceleration and deceleration of vehicles is accompanied by pitch motions that may influence sickness. HYPOTHESES: It was hypothesized that: (1) a visual scene would influence sickness caused by combined fore-and-aft and pitch oscillation; and (2) sickness would be dependent on the phase between the fore-and-aft oscillation and the pitch oscillation. METHOD: While viewing one of three visual scenes (internal view, blindfold, or external view), 6 groups of 20 subjects were exposed for 30 min to 1 of 2 motions (in-phase or out-of-phase combinations of 0.1 Hz fore-and-aft and pitch oscillation). The 0.1-Hz fore-and-aft oscillation at +/- 1.26 ms(-2) rms (displacement of +/- 3.18 m) was combined with +/- 3.69 degrees pitch oscillation either in phase (so the pitch increased acceleration in the plane of the seat to +/- 1.89 ms(-2)) or out of phase (to reduce acceleration to +/- 0.63 ms(-2)). RESULTS: With both types of motion (in-phase and out-of-phase oscillation) there was significantly less sickness with an external view than with an internal view or a blindfold. There was evidence of an interaction between the effects of viewing condition and the effect of the phase between the fore-and-aft and the pitch oscillation consistent with blindfolded subjects experiencing less sickness when they experienced greater forces. CONCLUSIONS: Motion sickness caused by combined fore-and-aft and pitch oscillation depends on both the visual scene and the phase between the fore-and-aft and pitch motions. The minimization of sickness arising from such motions should involve the optimization of both the visual environment and the phase.