Ultrasonic array sensor for indoor presence detection

Reliable detection of user presence is key in realizing energy-efficient occupancy-adaptive indoor lighting systems. We present an ultrasonic array sensor for reliable presence detection in indoor spaces. Short bursts of sinusoidal pulses are transmitted periodically from the sensor. The objective is to then determine presence of a user within the sensing region by processing the received echoes at the receiver array. Zones of movements are identified with coarse range and direction-of-arrival estimates using moving target indicator processing and conventional beamforming. Tracking is further applied on the resulting zone estimates to improve reliability of detection. Using a prototype implementation, we show that the proposed ultrasonic array sensor achieves better detection results compared to a state-of-art passive infrared sensor.