A Plug-and-Play Realization of Decentralized Feedback Control for Smart Lighting Systems

This paper proposes decentralized feedback controllers with plug-and-play capability for a class of smart lighting systems. In these systems, each light fixture has a spectrally tunable light source and a multichannel color sensor, and no communication is required between fixtures. Further, the light transport in the illuminated space is diagonally dominant, i.e., the light sensed by each sensor is primarily from the source in the same fixture. The controller design problems are formulated and solved for two cases of decentralized setpoint tracking and decentralized quadratic optimal control (with tracking error and energy penalty). For the decentralized setpoint tracking problem, a mechanism is proposed to automatically determine the feedback gains using individual sensor measurements in a plug-and-play fashion without the knowledge of the light transport model of the illuminated space. For the decentralized quadratic optimal control, the design problem is approximated with a series of local optimization problems, which are solved in a decentralized manner using individual sensor measurements. A suboptimality bound for the solution of the approximated problem compared with the global optimum is obtained. The performance of the suggested controllers in terms of achievement of a desired setpoint and daylight harvesting for energy saving is validated and evaluated based on typical lighting parameters in a room-scale experimental testbed with light-emitting diode fixtures and color sensors.