ROBUST ADAPTIVE CONTROL OF YEAST FED-BATCH CULTURES

Abstract A robust controller combining a feedforward compensator (for the measured disturbance) and a feedback RST controller is designed for the control of S. cerevisiae cultures. The controller is based on the linearization of Sonnleitner's model allowing a simple transfer function model to be derived, which describes the relation between the ethanol concentration, the substrate feed and a measurable disturbance - image of the substrate demand for cell growth. This control scheme is made robust to neglected high frequency dynamics (of glucose and oxygen) and uncertain stoichiometry coefficients using the observer polynomial. This control scheme, whose performance is demonstrated in simulation, requires only the on-line measurements of the ethanol concentration and bioreactor volume, estimation of the oxygen transfer rate, and minimal a priori process knowledge, i.e. only one stoichiometric coefficient.