Monitoring Person on Bed Using Millimeter-Wave Radar Sensor

In this paper, we propose a method for finding the moment when the state of a person on the bed changes and estimating the person's respiration rate. First, we install a millimeter-wave band radar sensor on the bed and acquire reflected radar signals for a person and a baby doll that mimics the respiration rate of a person. Then, the moment when the subject's breathing pattern changes is detected by applying the change point detection algorithm to the spectrogram. In addition, the respiration rate of the subject is estimated from the change in the distance between the subject and the radar over time. Through the proposed method, we can effectively find the moment when the subject's breathing characteristics change rapidly. Moreover, the respiration rate estimated from the radar sensor data shows an error rate of less than 3.5% when compared with the actual respiration rate.