On the road to comfort: Evaluating the influence of motion predictability on motion sickness in automated vehicles.

Automated vehicles could increase the risk of motion sickness because occupants are not involved in driving and do not watch the road. This paper aimed to investigate the influence of motion predictability on motion sickness in automated vehicles, as better motion anticipation is believed to mitigate motion sickness. In a simulator-based study, twenty participants experienced two driving conditions differing only in turn directions. The repetitive condition featured a repeating turn direction pattern. The non-repetitive condition contained pseudo-randomly ordered turn directions. To mimic an 'eyes-off-the-road' setting and prevent visual motion anticipation, road visuals were omitted. No significant differences in sickness or head motion, a metric for motion anticipation, were found between the conditions. No participant recognised the repeating turn pattern. This suggests no increased motion anticipation in the repetitive condition, possibly due to a reduced ability to recognise a repeating motion pattern in one degree of freedom within more complex motion. Motion anticipation is believed to mitigate motion sickness. However, in this simulator-based study on automated vehicles, no significant differences in motion anticipation or sickness were observed between repetitive and non-repetitive turn directions. Recognition of a repeating motion pattern in one degree of freedom might be diminished when it is part of more complex motion.