  Motion sickness (MS) has long been a common complaint in road transportation.
However, in the era of driving automation, MS has become an increasingly
significant issue. The future intelligent vehicle is envisioned as a mobile
space for work or entertainment, but unfortunately passengers' engagement in
non-driving tasks may exacerbate MS. Finding effective MS countermeasures is
crucial to ensure a pleasant passenger experience. Nevertheless, due to the
complex mechanism of MS, there are numerous challenges in mitigating it,
hindering the development of practical countermeasures. To address this, we
first review two prevalent theories explaining the mechanism of MS.
Subsequently, this paper provides a summary of current subjective and objective
approaches for quantifying motion sickness levels. Then, it surveys existing
methods for alleviating MS, including passenger adjustment, intelligent vehicle
solutions, and motion cues of various modalities. Furthermore, we outline the
limitations and remaining challenges of current research and highlight novel
opportunities in the context of intelligent vehicles. Finally, we propose an
integrated framework for alleviating MS. The findings of this review will
enhance our understanding of carsickness and offer valuable insights for future
research and practice in MS mitigation within modern vehicles.
