Development of Simulating Wave System (SWS) for a Hospitable Sleeping Environment with Artificial Vibration

In this study, we propose a simulating wave system (SWS) that provides a comfortable sleep environment to release stress. This system realizes floating-feeling as if it feels like floating on the water surface by automatically swinging the seat back and forth, left and right. First, this paper describes the mechanical structure and control method on the developed prototype SWS. Since we assess the comfort levels of SWS with subjective and objective evaluations, we describe these criteria in detail. For objective evaluation, four types of criteria, such as LF/HF, ellipse area, SD1/SD2, and SD1, are adopted. LF/HF calculated from the Fourier transformed subject’s heart rate variability (HRV) and SD1/SD2 meaning the ratio of the major axis to the minor axis on a Lorenz plot are the values indicating sympathetic nerve activity. Ellipse areas on the Lorenz plot and minor axis SD1 are used as the value of parasympathetic nerve activity. For the subjective evaluation, a visual analog scale(VAS) is adopted that is a method of assessing sensation on a horizontal straight line ranging from 0 to 100 percent. This paper reports the research results of the proposed SWS on the above items.