Centralized lighting control with luminaire-based occupancy and light sensing

We consider control of multiple luminaires with a central controller and occupancy and light sensors co-located at the luminaires. The sensors periodically provide local occupancy state and illumination information to the central controller. Using this sensor feedback, the central controller determines the dimming levels of the luminaires so as to adapt artificial light output to changing daylight levels and occupancy conditions, in an energy efficient way. We propose a multivariable feedback controller based on optimizing a cost function with a component corresponding to power consumption and another corresponding to illumination errors at the light sensors. The constraints are that the attained illumination value at the light sensors be no smaller than the reference set-points and that the dimming levels of luminaires are within physical limits. We compare the performance of the proposed controller with a simple stand-alone reference controller. We show via simulations in an open-plan office lighting system that the proposed controller has better performance in terms of achieving the reference set-points.