Variable structure estimation and control of nonlinear distributed parameter bioreactors

Estimation and control design issues for distributed parameter bioreactors are discussed in relation to a model consisting of a nonlinear partial differential system. The regulation problem consists of maintaining the substrate concentration at the outlet of the reactor at a desired value. The model describes microbial growth and substrate consumption in a fixed-bed reactor. The behaviour of living organisms is hardly known since biological parameters are time varying over a long period. Moreover, online biomass concentration sensors are not available. Variable structure control systems are known to be robust. A joint estimator of states and parameters and a controller is designed by using the variable structure system approach. The control variable concerned is very smooth and chattering does not exist. The robustness of the different algorithms is shown by means of numerical simulations