On-line estimation of the reaction rates from sampled measurements in bioreactors

Abstract Simple high gain observer-based estimators which allow the estimation of the reaction rates from the measurements of component concentrations inside bioreactors are presented. The main properties of these estimators lie in the fact that the measurements of the component concentrations are non available in a continuous manner, as generally assumed in most available algorithms, but only at sampling instants. The proposed estimators, called continuous-discrete observer, result from the design of available estimators which assume the availability of the measurements in a continuous manner. It is shown that for relatively small values for the sampling periods, which may be time-varying, the proposed continuous-discrete observers inherit the same performance as the purely continuous observers in terms of the accuracy of estimation and sensitivity to noise measurements. Simulations results dealing with typical bioreactor example are given in order to illustrate the performance and the main properties of the proposed estimators.