Wireless Sensor and Actuator Networks for Lighting Energy ...

interfacing and controlling the dimmable ballasts. The research system is realized
through a series of implementations from a prototyping luminaire structure, to a private
office, to a small share-space office with increased scale and complexity. Each of the
realizations serves a different purpose and makes a unique contribution to the research.
Photosensors and ballast actuators are an integral component of the research
system. Both the photosensors and the ballast actuators are integrated with wireless
platforms known as ‘smart motes’. The wireless photosensor possesses a response
similar to a human eye so as to accurately estimate the illuminance on the desktop and
transmit the readings over the radio. The ballast actuator is an add-on actuation module
interfacing with the dimmable ballast. The actuation module receives wireless actuation
commands and translates them into ballast control signals to dim the lights or toggle the
lights on/off.
The first implementation of the research system was realized on a prototyping
single-luminaire structure equipped with a dimmable ballast. Due to the simplicity of
the structure, it is highly configurable for various purposes and has served as a testbed
for verifying ideas, developing prototypes, and testing algorithms along the course of
this research. The wireless photosensors, the developed sensor validation and fusion
algorithm, the wireless ballast actuators, and a simple closed-loop wireless lighting
control system were tested using this structure.
A private office with four luminaires was retrofitted with the research system as
the second implementation. A sensor network for measuring desktop illuminance and an
actuator network for actuating the four dimmable luminaires were realized. Both
networks were implemented with simple networking protocols and were coordinated by
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