Deployment of a Wireless Ultrasonic Sensor Array for Psychological Monitoring

The deployment of a wireless sensor network to monitor subjects’ locations and relative distances during psychological experiments is discussed. As its primary function, an overhead array of ultrasound sensors automatically tracks a parent, child and stranger over a 4.45 m×4.23 m observation area. The array of ultrasonic-equipped motes can resolve two point targets separated by at least 73 cm. Each sensor can detect the range to the nearest object with 20 cm resolution. Challenges with setting up the 6× 6 ultrasonic imaging array and with establishing a Kalman tracking filter are also detailed. This WiPsy (Wireless sensors for Psychology research) system provides accurate, real-time quantitative metrics for psychological evaluation in lieu of traditional qualitative manual coding. Moreover, tracking subjects using ultrasound sensors is less error-prone than existing methods that track based on human coding of video. Overall, WiPsy strives to streamline data acquisition, processing, and analysis by providing previously unavailable assessment parameters.