3D ultrasonic tagging system for observing human activity

This paper describes an ultrasonic tagging system developed for robustly observing human activity in a living area. Using ultrasonic transmitter tags with unique identifiers, the system is shown through experimental application to be able to track the three-dimensional motion of tagged objects in real time with high accuracy, resolution and robustness to occlusion. The use of an ultrasonic system is desirable because of its low cost and use of commercial components, and the proposed system achieves high accuracy and robustness through the use of many redundant sensors. The system employs multilateration to locate tagged objects using one of two estimation algorithms, a least-squares optimization method or a random sample consensus method.