Test-track and on-road studies: Methodological insights on the assessment of carsickness and its modulating factors

The research on motion sickness and effective countermeasures has gained additional attention due to the ongoing development of highly automated driving vehicles. In order to understand the phenomenon of motion sickness better and support effective testing, this work sheds lights on motion sickness considering essential modulating factors: The relation between the development of carsickness and testing environment is explored in relation to psychological factors. Simultaneously, carsickness is often stimulated by non-driving related tasks (NDRTs) and publications have shown different effects on motion sickness by various NDRTs. Therefore, it is also investigated whether the optical flow during NDRTs influences carsickness. Lastly, it is investigated whether there is an effect on performance caused by carsickness across different testing environments. 47 participants participated in a within-subject study in a vehicle either driving on a public road or on a test track. While administering comparable accelerations and two randomly assigned NDRTs, carsickness, psychological factors and performance were measured within these environments. The results indicate that it was possible to set-up rides in both environments which led to comparable motion sickness stimuli based on the vehicle accelerations. The optical flow did not significantly affect carsickness on a population-level but illustrated ~15% on individual level. At the same time, few differences could be found among psychological factors, but they do not indicate that the transfer of results between testing environments would not be valid. Lastly, cognitive performance was affected by the two testing environments with regard to the reaction time. This work elucidates on the one hand that multiple factors influence motion sickness, though much remains, yet, to be understood. On the other hand, the feasibility of conducting comparable studies in different testing environments is shown. If such transfer is fully realized, motion sickness research can proceed in an effective and intertwined way.