Study on movement detection in care environment using precise ultrasonic distance measurement at 40 kHz installed in sensor network

Sensor network which connects many sensors via small-scale private wireless network such as ZigBee and Z-Wave has been studied all over the world these days. In the future, it will provide home/office-circumstance monitoring, i.e. taking care of old people, preventing crime and maintaining security. In this paper, we have proposed a new care-environment monitoring system using novel ultrasonic distance-measurement and movement-detection method installed in ZigBee-based sensor network. Comparison between our method at 40 kHz and the conventional millimeter-wave radar mounted on high-end vehicles will be illustrated. Developed automatic-measurement system and fundamental experimental results will be presented.