A low-cost energy-harvesting sensory headwear useful for tetraplegic people to drive home automation

Abstract

Tetraplegic people need continuous assistance in every daily activity. Assistive technologies can improve, to a certain degree, their quality of life allowing partial autonomy with powering their residual capability of movements. In this work, we propose a novel wire-free low-cost user-friendly battery-operated sensory headwear, which allows home automation controlled by head movements. The headwear is equipped with an inertial measurement unit (IMU), a low power microcontroller and a transmission module to measure, condition and wireless transmit data related to head movements. Such a sensory headwear allows the subject, simply by head movements, either to select one computer icon among an ensemble or to select one actuator, among a number of others. Each icon and each actuator drive a specific physical action in a home or work environment. We devoted particular efforts to increase the battery autonomy, by means of radio frequency energy harvesting solutions, for lasting operational mode. The harvester, based on commercial chipsets, was optimized in the 2.4–2.5 GHz range to exploit headwear itself radiated energy and environmental energy, in particular from Wi-Fi and Bluetooth surrounding devices. An average efficiency, calculated as output to input power ratio, of around 60% at −5dBm input power level has been obtained.