DESIGN OF A ROBUST CONTROLLER FOR THE SUBSTRATE CONCENTRATION IN BIOREACTORS

This paper presents the control of substrate concentration in a continuously operated biological reactor. The bioreactor can be represented by a nonlinear time-variant mathematical model. Several biotechnical processes can be described by using simple modifications of that model. An approach is presented that gives a description largely independent of the growing behaviour of bacteria, so that the controller can be applied to different bacteria cultures. The time-varying properties of the measurement system are considered. Using a model-based nonlinear predictive control strategy, the concept of the controller is derived. Considering special features of the process the design of the controller is presented. The results of the stability analysis of the system are discussed. A concept for selftuning is derived with the aim of a fully automated design procedure. The robustness of the design is presented in a technical application.