An Empirical Study of Virtual Reality Sickness based on Self-motion Perception

近年来，虚拟现实（VR）系统在医学、康复和教育等领域得到了广泛的应用。因此，构建安全舒适的虚拟现实系统需要充分考虑人的因素。然而，真正充分考虑人的因素的VR系统却很少。希望制定安全VR系统的指导方针，以防止人类产生晕动病等不良反应。因此，我们开展了一个研究项目，如何在虚拟环境中预防或减少VR疾病。首先，我们开发了一个集成的VR刺激系统，可以同时控制和显示视觉、听觉和前庭刺激，然后是人体反应的监测系统。其次，使用这些系统，我们检查了是否可以通过不同类型的感官刺激（如声学或前庭刺激）控制与VR疾病相关的视觉诱导的自我运动知觉（vecection）。实验结果表明，声刺激和前庭刺激能有效地减少矢度。此外，我们使用视频透明MHD检查了混合现实下真实单词和虚拟单词之间的时空差距对人体的影响。实验结果表明，使用3D-HMD的操作效率优于2D-HMD，尽管操作效率强烈依赖于时间延迟。除上述研究外，副作用还包括：1)长期使用头戴式腕带对人眼视觉系统的影响；2)宽视场头戴式腕带产生的光动力刺激对站立平衡的影响；3)固定靶对扭性眼震的影响；4)老年人跌倒的视觉系统影响；5)同时使用透明头戴式腕带和自动语音识别系统的助听器系统的开发。

In recent Virtual Reality (VR) systems, various practical applications have been expected in many fields such as medicine, rehabilitation and education. Therefore, enough considerationn of human factors are needed to construct the safe and comfortable VR systems. However, there is seldom a VR system that sufficiently considered the human factors actually. A guideline for the safe VR systems to prevent human from undesirable reactions such as motion sickness is desired. So we carried out a research project how to prevent or reduce VR sickness in virtual environments. First, we developed an integrated VR stimulation system that could control and display visual, acoustic and vestibular stimuli simultaneously, and then a monitoring system of human body reactions. Secondly, using these systems, we examined whether visually induced self-motion perception (vection) that was possible to relate the VR sickness could control or not by a different kind of sensory stimulation such as an acoustic or vestibular stimulus. From our experimental results, it was ascertained that the acoustic and vestibular stimulus was effective to reduce the vection. In addition, we examined influence on human body concerning temporal and spatial gaps between a real and a virtual word under Mixed Reality using a video see-through MHD. From our experimental results, it was ascertained that manipulation efficiency in using a 3D-HMD was better than a 2D-HMD although the efficiency strongly depended on time delay. Side results except the above-mentioned studies were 1) influence on human visual system by using a HMD for a long time, 2) effects of optokinetic stimulations produced from a wide view HMD on standing balance, 3) effects of a fixation target on torsional optokinetic nystagmus, 4) visual system associated with falls in the elderly, and 5) development of a hearing aid system using both a see-through HMD and an automatic speech recognition system.