Batteryless Bicycle Speed Recorder with Hub Dynamo and FM/AM Radio as Time Stamp Function

Abstract

A batteryless bicycle speed recorder with a hub dynamo and FM/AM radio has been developed. The hub dynamo functions as both a power source and a speed sensor. It produces a voltage waveform with fourteen AC cycles per rotation of the bicycle wheel, which enables precise determination of speed and acceleration. A sound data of radio broadcasting was also used as time stamp function. The data is stored in a magnetoresistive random-access memory (MRAM). A road test showed that a fabricated speed recorder mounted on a bicycle stored and reproduced accurate values of a large acceleration and its duration when the brakes were suddenly applied while the bicycle was being ridden.