Joseph A. Paradiso, R. Bainbridge

Abstract

For wearable computing to become more widely accepted, the associated Human-Computer Interface must move past today's keyboard, keypad, touch screen, or other bulky hand-held interfaces to allow a user to specify input through their fingers without taking their eyes and attention off their immediate focus. Accordingly, we have developed a wearable system to track hand gestures with passive RFID sensor tags. This system is composed of an ultra-high frequency (UHF) reader and small, passive, finger-worn tags powered by transmit RF energy, each equipped with a variety of sensors that could be used to detect gestures. The primary physical goals of the system were to be comfortable and wearable without interfering with other everyday activities while tracking particular hand movements that could be used to control a wearable computer or aid in interaction with ubiquitous or other wearable devices. This paper first introduces our hardware, then gives some example user interface implementations, such as a mouse scrolled by hand position and a click specified by finger proximity, entering input by touching fingers, setting options when moving the hand to a particular spot of the user's apparel labeled with a passive RFID tag, and otherwise mapping control onto motion of the hand, arm, and fingers. The overall system was fully functional, but as this is an early implementation, it was still very much limited by transmit power and antenna efficiency, due to the constraints on the size of the passive tags. Means of scaling to lower power and smaller size are suggested.