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Control of lighting systems that adapt to daylight is known to be energy efficient. An underlying challenge in such control is the estimation of daylight level. We consider the problem of disaggregated estimation of the daylight and artificial light levels in a lighting system. To facilitate this disaggregation, the light output from each light source is modulated and the system operates under a carrier sense multiple access with collision avoidance protocol. At the light sensor, the received electrical signal is a superposition of the light contributions from daylight and artificial light sources. We present algorithms to process the sensor signal to estimate the daylight and artificial light levels. An optimum joint least-squares estimator is analyzed and, subsequently, two practical successive estimation algorithms are proposed. The performance of these algorithms is evaluated analytically and validated via experimental results.
Date of Publication: Dec. 2012