Prototype energy harvesting wheel speed sensor for anti-lock braking

A prototype energy harvesting wireless wheel speed sensor is presented, which implements two basic functions for anti-lock braking, namely periodic transmission of wheel speed and near real-time detection of the start/stop of wheel rotation. The sensor is powered by reusing a commercially available variable reluctance electromagnetic speed sensor as an energy harvesting transducer. In an experimental setup, a maximum harvestable power of ~1 mW from the transducer (at a wheel rotational speed of ~ 300 RPM) has been measured which has been used for powering the autonomous sensor. Each recurrent operation in the prototype autonomous sensor consumes a maximum of ~23 mW of power in bursts for ~3 ms, and a simple statistical model of wheel behavior has been proposed based on which the power consumption of the sensor has been calculated on average.