Use of non linear software sensor to monitor the internal state of a culture of microalgae

We construct nonlinear software sensors in order to monitor the internal state of a culture of microalgae. We use the Droop model to represent the growth of phytoplanktonic cells limited by nutrients in the bioreactor. We show that this model is an element of a general class of systems for which the conditions for the exponential convergence of high gain observers are proved. The software sensors is then designed and applied in a nitrate-limited microalgae chemostat experiment performed in a computer controlled fluctuating environment. The efficiency of the software sensor is discussed.

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