An Energy-driven Wireless Bicycle Trip Counter with Zero Energy Storage

This paper presents the implementation of a bicycle trip counter, which measures cycling speed, traveled distance, and cycling time, that is directly powered from tiny periodic pulses of energy with only the intrinsically present decoupling capacitance as an energy buffer. To cope with the highly variable amount of energy generated during each pulse, an energy-driven approach is used. The core principles in this approach are to dynamically adjust operational mode according to energy availability, to scale performance, for example sensing accuracy, proportional to energy harvested, and to perform intermittent or transient computing to enable computation across multiple power cycles. The device presented is able to start operation from energy supply pulses as low as 4 uJ, where a rough estimate of the sensing parameters is done, and perform increasingly complex and time-consuming tasks such as additional more accurate measurements, sensor fusion, and filtering computations as more energy becomes available.