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Control Algorithm

When specifying a photosensor control system, the control algorithm is the most important characteristic and the one to consider first. The control algorithm describes the exact nature of the photosensor ouput as a function of the input. The inputs to the algorithm are the optical signal (what the sensor senses) and any controls that are set when the system is commissioned. The output from the algorithm is the control voltage sent to the dimming ballast.

Three Basic Control Algorithms

There is no limit to the number of different control algorithms that can be developed for specific situations. With the advent of digital signal processing, control algorithms of increasing complexity can be easily realized.

However, even the relatively simple algorithms used today can be effective when implemented correctly.

In general, existing photosensors use one or a combination of three basic control algorithms: integral (reset), open-loop proportional, and closed-loop proportional. All three are readily implemented in either analog or digital designs.

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