BUBBLE TUBE SENSOR FOR BODY MOVEMENT DETECTION

There are many needs for detecting the presence or absence of people on the bed, getting on and off, and detecting body movements. The author propose a cost effective high sensivity acceleration sensor, which may become suitable for those needs by attaching it to the bed frame. The sensor itself is based on a bubble tube and optical detection of the bubble movements. When the subject got on and off the bed, the change in the root mean square mean second was the largest. Acceleration of the head, limbs, and trunk was positively correlated with the output of the bubble tube sensor. Details of the sensor and experiments to confirm its validity are discussed in this paper.