Minimally privacy-violative system for locating human by ultrasonic radar embedded on ceiling

Violating the privacy of individuals with systems that measure daily human activities is unacceptable in our society. In this paper, the authors propose a system using ultrasonic radar embedded in the ceiling of a room to locate human individuals with a minimum violation of privacy. It is expected that this system is used in the prevention of accidents among aged persons suffering from Alzheimer's disease. The proposed system determines the three-dimensional position of a person's head by assuming that the human head is an object that will move at a relatively high vertical position within a living area. In this study, the method used to locate the human head is analyzed theoretically from the perspective of acoustics. The feasibility of the proposed system is confirmed by experimental results using a system constructed by the authors.