A Systematic Investigation into Induction and Mitigation Methods of Motion Sickness in Passengers of Automated Vehicles

Abstract

Automated vehicle technology can not only transform vehicle behavior on roadways, but also transform users from an active driver to a passenger, with increase in automation levels, such as going from SAE Levels 0 through 2, to Levels 3 through 5. As passengers engage in non-driving related tasks (NDRTs) inside a moving vehicle, they experience limited vehicle control and external awareness. Such conditions can lead to passengers becoming motion sick. Since two out of three passengers are prone to motion sickness, even mild symptoms of motion sickness can severely influence users’ experience in automated vehicles. This dissertation includes four studies to investigate the human factors challenge of motion sickness in passengers of automated vehicles. The first study consists of a systematic literature review following the PRISMA framework. Forty-one papers were selected to be qualitatively analyzed based on which an overarching research framework was proposed. The second study focused on verifying if driving styles simulated on a motion-based driving simulator could be used to artificially induce motion sickness in a safe controlled manner. The third study investigated two driving styles with and without an NDRT to corroborate the findings from the previous study. In the fourth and final study, the focus shifted to mitigating motion sickness. A novel auditory display was developed based on existing literature to reduce motion sickness. Findings from the second and third studies confirmed that strong lateral accelerations could indeed induce motion sickness, and engagement in a cognitively demanding task could lower motion sickness. Based on these findings, the Cognitive Distraction Effect was proposed in the third study. The fourth study, that utilized the verified motion sickness inducing condition from the second and third studies, found that the presence of repeated spatialized anticipatory auditory cues increased motion sickness due to the added sense of vection from the auditory stimuli. This was a unique observation that aligned with recent literature. Furthermore, the fourth study also found evidence in support of the Cognitive Distraction Effect. In summary, this dissertation provides a comprehensive investigation into developing our understanding of motion sickness in passengers of automated vehicles. Three unique contributions are proposed. One, it is possible to induce motion sickness in a safe replicable manner in a laboratory without the need for real-world driving. Second, cognitive engagement in a demanding task can suppress physiological symptoms of motion sickness, suggesting NDRT engagement could have benefits for mitigating motion sickness. Finally, the dissertation sheds new light on the senses that contribute towards development of motion sickness, in that even the hearing system has a role to play in maintaining balance and orientation, in addition to the visual and vestibular systems.