Light-harvesting wireless sensors for indoor lighting control

A light-harvesting wireless sensing system is proposed for indoor lighting control. A low-power light sensor and motion sensor operates on a photovoltaic cell that charges based on ambient daylight and artificial light. These sensors, respectively, measure the illuminance level and occupancy over their sensing regions. An ambient illuminance-aware sensing protocol is used to communicate this information using a wireless radio to a central controller. The controller employs a closed-loop illuminance feedback control algorithm to determine the dimming levels of the luminaires such that a desired set-point at the light sensors is achieved. The proposed system design allows operation of the wireless sensing prototype module entirely on energy harvested from the ambient environment in a complete dark environment with a lifetime of 20 h, making the solution suitable for practical indoor lighting applications.