A Self-Powered, Wireless Pushbutton Controller
We have developed a compact, wireless, barreryless pushbutton controller that transmits a 12-bit digital ID code to the vicinity when it is pressed. The device produces on the order of a milliJoule at 3 Volts when pushed, enabling several cycles of the ID code to be transmitted over scores of meters. Previous approaches used piezoceramic actuators to send simple impulses across Hertzian Resonators, such as this toy pager that used to be marketed by Tomy. Our device uses a reactively-matched transformer to drop the impedance of the piezo source, enabling one push to easily power low-voltage circuitry that can produce and transmit the code. This device has myriad applications, e.g., in places where a control interface is desired, but where physical wiring is impractical or too expensive, or where an embedded battery is undesireable because of limited shelf life or environmental concerns. This work evolved out of our prior project on power harvesting in shoes.
Relevant Videos, Papers, and Articles:
Hi-Res Video (7.9 meg) or Low-Res Video (2.3 Meg) of Mark demonstrating the pushbutton in action. The receiver makes a beep when it detects the transmitted code. The timbre of the beep can be changed by changing the last beep of the code - Mark is doing this by flipping a slide switch on the controller between each strike. He walks well our of the Lab with it as it still works, as seen in the conclusion of this clip.
Paper presenting details at the Ubicomp 2001 Conference:
"A Compact, Wireless, Self-Powered Pushbutton Controller," Joseph A. Paradiso and Mark Feldmeier. In Abowd, G.D., Brumitt, B., and Shafer, S., eds, "Ubicomp 2001: Ubiquitous Computing," ACM UBICOMP Conference Proceedings, Atlanta GA, Sept. 2001, Springer-Verlag Berlin Heidelberg, 2001, pp. 299-304.
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