PI Observer-based Control for Biomass Regulation under Measurement Delays

Abstract

The present paper deals with the issue of measurement delays which constitute a very prominent problem faced by most control systems. The system considered is that of a bioreactor used for the biological treatment of wastewater. The recording of the output substrate concentration of such systems usually involves a delay which results from the dependency of the flow of the liquid on its consistency. A PI observer-based control is applied and its performance is analysed in terms of the maximum delay for which the system is stable and converges as well as in terms of the convergence times. Based on these parameters, the results are compared to those obtained by a feedback linearising observer-based system. This comparative analysis showed that the PI controller performed better than the feedback controller, hence confirming its efficiency in biomass regulation in the presence of delayed measurements.