Enhanced MRAC Based Parallel Cascade Control Strategy for Unstable Process with Application to a Continuous Bioreactor

Abstract

In this paper, Enhanced Model Reference Adaptive Control (E-MRAC) based Parallel Cascade Control strategy (PCC) is proposed for the control of unstable continuous bioreactor. This control system consists of secondary and primary loop. The secondary loop comprises of PID controller, which is designed based on the direct synthesis method. In order to achieve stable responses for unstable processes like continuous bioreactor, non linear control strategy in the primary loop would gain edge over linear control. Hence, the Enhanced MRAC (includes smith predictor) is introduced in the primary loop. The presence of Smith predictor has minimized the discrepancies due to dead times. This seems to be an added advantage over existing ones. From the simulation studies it is observed that Enhanced MRAC based PCC has shown better tracking performance when compared to the PID based PCC control strategy.