A Transmitter—Receiver System for Long-Range Capacitive Sensing Applications

Human occupancy detection and localization are important in a variety of smart building applications including building security, assisted living monitors, and energy-efficient heating ventilation and air cooling and lighting. Current implementation of such systems is limited by motion-sensor technologies, e.g., passive infrared (PIR) and ultrasonic sensors, which substitute as occupancy detectors but ultimately suffer from an inability to detect stationary objects. Capacitive sensing can detect stationary objects, but the technology has almost exclusively been developed for short-range human detection and localization, e.g., touch-screen human interfacing of smart devices. This paper presents a transmitter-receiver platform for research and development of capacitive sensing for long-range human occupancy detection and localization. During testing, the system revealed a detection range of 3.5 m, a typical room dimension in homes. Further, tests of a multitransmitter single-receiver system in a 3.2 m × 3.2 m space showed the system's potential for occupant localization. Ultimately, this system represents an alternative to PIR and ultrasonic motion sensors, and has the potential to increase smart building system implementation.