Akisue Kuramoto

Mechanical Bed for Investigating Sleep-Inducing Vibration

In running cars or trains, passengers often feel sleepy. Our study focuses on this physiological phenomenon. If a machine can reproduce this phenomenon, it is feasible to put a person, such as an insomnia patient or an infant, to sleep without any harmful effects. The results of our previous study suggest that low-frequency vibration induces sleep. This report describes a new mechanical bed for inducing sleep and discusses the effects of different vibration conditions. The new bed has two active DOFs in the vertical and horizontal directions to examine the anisotropy of sensation. The bed includes three main parts: a vertical driver unit, a horizontal driver unit, and a unique 2-DOF counterweight system to reduce driving force and noise. With regard to motion accuracy, the maximum motion error in the vertical direction lifting 75 kg load was only 0.06 mm with a 5.0 mm amplitude of a 0.5 Hz sinusoidal wave. The results of excitation experiments with 10 subjects showed a significant difference in sleep latency between the conditions with vibration and without vibration. Furthermore, the average latency with insensible vibration (amplitude = 2.4 mm) was shorter than that with sensible vibration (amplitude = 7.5 mm). These results suggest the ability of appropriate vibration to induce sleep.In running cars or trains, passengers often feel sleepy. Our study focuses on this physiological phenomenon. If a machine can reproduce this phenomenon, it is feasible to put a person, such as an insomnia patient or an infant, to sleep without any harmful effects. The results of our previous study suggest that low-frequency vibration induces sleep. This report describes a new mechanical bed for inducing sleep and discusses the effects of different vibration conditions. The new bed has two active DOFs in the vertical and horizontal directions to examine the anisotropy of sensation. The bed includes three main parts: a vertical driver unit, a horizontal driver unit, and a unique 2-DOF counterweight system to reduce driving force and noise. With regard to motion accuracy, the maximum motion error in the vertical direction lifting 75 kg load was only 0.06 mm with a 5.0 mm amplitude of a 0.5 Hz sinusoidal wave. The results of excitation experiments with 10 subjects showed a significant difference in sleep latency between the conditions with vibration and without vibration. Furthermore, the average latency with insensible vibration (amplitude = 2.4 mm) was shorter than that with sensible vibration (amplitude = 7.5 mm). These results suggest the ability of appropriate vibration to induce sleep.

Development of an intelligent pillow with multiple flexible actuators

This study aims to develop an intelligent bedding that automatically provides a comfortable sleep condition for each person. This paper proposes a pillow-type device which actively changes its shape and stiffness. The device is composed of multiple flexible actuators which are driven by air pressure. Each actuator has two types of sensors: an internal pressure sensor and five contact pressure sensors. These sensors are used for monitoring the support condition of user’s head and neck. We developed a pillow system capable of controlling the internal pressure and contact pressure of each actuator in order to realize a comfortable condition for sleep. The pillow system successfully controlled the center of contact pressure to the target position. To elucidate comfortable and uncomfortable support conditions, pressure distributions on the head and neck were measured by the system. The result indicates that accurate control of the center of contact pressure is important for comfortableness.

Development of intelligent integrated bedding system Transformable pillow and mattress with multiple flexible actuators

This study proposes an intelligent bedding system that actively changes its shape and stiffness with multiple flexible actuators. The proposed system provides mechanical conditions for comfortable sleep by feedback control. The system comprises air bag actuators, feedback control system and an individual body simulator. Authors plan to control the actuators on the basis of the body simulator, which calculates appropriate body support condition. To develop the simulator, this paper discusses a mathematical model of human body to obtain pressure distribution and posture in supine position. Devices of pillow and mattress with flexible actuators are also described.