Feedback control of smart lighting systems based on color science

With the recent developments in the solid state lighting industry, smart lighting systems are becoming a reality. These systems combine advanced light sources (light emitting diodes, or LEDs), advanced color sensors, and control algorithms to achieve energy efficiency, enhanced productivity, and healthy and comfortable lighting. The existing literature on general control of lighting systems does not exploit certain advantages that multi-color LED lighting systems have to offer, particularly the color tunability. This thesis proposes a color science approach to the problem of feedback controller design for color-tunable smart lighting systems, accounting for energy efficiency and customized and comfortable lighting. A general framework for the formulation of the control problem in lighting systems is presented, and different closed loop strategies for determination of the dimming levels for the color channels are proposed. Specifically, two classes of centralized and decentralized approaches are presented and the controller design methodology as well as system performances in both cases are demonstrated and compared. Moreover, this framework is generalized to perform feedback control based on estimation of the light field using computer graphics software.;For centralized control of lighting systems, the controller design problem is formulated as an optimization problem balancing light quality, human comfort, light field uniformity, and energy efficiency. Since the light transport model changes over time, an adaptation scheme is used to update it on the fly using input-output measurements. Further, an optimization-based methodology for feedback control of lighting systems with redundancy in the number of LED channels is presented. For decentralized control, 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, which significantly reduces the commissioning time for the lighting system. In this case, 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).;Finally, this thesis presents a framework for using graphical rendering tools along with point sensor measurements for estimating the light field and using this estimate for feedback control. Computer graphics software is used to efficiently and accurately model building spaces, while a game engine is used to render different lighting conditions for the space on the fly. For each of the mentioned methodologies, experimental and/or simulation results are used to demonstrate the performance of the proposed controllers in lighting testbeds. Two room-sized testbeds, equipped with color-tunable lights and color sensors, realized in the Smart Lighting Engineering Research Center located at Rensselaer Polytechnic Institute in Troy, New York, are used for this purpose.