Motion Sickness Modeling with Visual Vertical Estimation and Its Application to Autonomous Personal Mobility Vehicles

TL;DR

This work addresses motion sickness in autonomous personal mobility vehicles by extending the classic 6 DoF SVC model to include visually derived vertical information. It introduces a simple image-based VV estimator and a 6 DoF SVC--VV architecture that couples VV with vestibular signals through a visual-vestibular interaction pathway, enabling predicted motion sickness incidence (MSI) to reflect visual context such as reading during ride. Static validation shows VV estimates align closely with gravity ($ heta^{m{g}} ightarrow heta^{VV}$ with MAD ≈ $2.4^ ext{o}$ and $R^2=0.99$), while driving tests reveal the VV-informed model better captures elevated MSI when VV and gravity directions diverge (as in RAD). The results imply that incorporating VV improves predictive capability for occupant comfort in APMVs, guiding countermeasures and design for safer, more comfortable autonomous travel.

Abstract

Passengers (drivers) of level 3-5 autonomous personal mobility vehicles (APMV) and cars can perform non-driving tasks, such as reading books and smartphones, while driving. It has been pointed out that such activities may increase motion sickness. Many studies have been conducted to build countermeasures, of which various computational motion sickness models have been developed. Many of these are based on subjective vertical conflict (SVC) theory, which describes vertical changes in direction sensed by human sensory organs vs. those expected by the central nervous system. Such models are expected to be applied to autonomous driving scenarios. However, no current computational model can integrate visual vertical information with vestibular sensations. We proposed a 6 DoF SVC-VV model which add a visually perceived vertical block into a conventional six-degrees-of-freedom SVC model to predict VV directions from image data simulating the visual input of a human. Hence, a simple image-based VV estimation method is proposed. As the validation of the proposed model, this paper focuses on describing the fact that the motion sickness increases as a passenger reads a book while using an AMPV, assuming that visual vertical (VV) plays an important role. In the static experiment, it is demonstrated that the estimated VV by the proposed method accurately described the gravitational acceleration direction with a low mean absolute deviation. In addition, the results of the driving experiment using an APMV demonstrated that the proposed 6 DoF SVC-VV model could describe that the increased motion sickness experienced when the VV and gravitational acceleration directions were different.

Figures (7)

• Figure 1: Proposed 6 DoF SVC model including conflict of two-dimensional VV (6 DoF SVC--VV model).
• Figure 2: A WHILL model CR was used as the experimental vehicle. A camera and an IMU were set on a helmet to observe visual information and the acceleration as well as the angular velocity of passenger's head.
• Figure 4: Linear relationship between directions of VV and gravitational acceleration.
• Figure 5: Two driving scenarios: 1) autonomous driving (AD); 2) reading during autonomous driving (RAD).
• Figure 6: The path designed for slalom driving.