The Effect of the Tuning Parameters on the Performance of the Parametric and Nonparametric Model Based Control Methods for Growth Medium Temperature of Baker's Yeast Production

Abstract

In this study, nonparametric and parametric model based control methods were applied in the control line in order to control the growth medium temperature of aerobic baker's yeast production in a batch bioreactor, and the performance was compared experimentally and theoretically. For a non-parametric model, an experimental reaction curve was found by performing the open-loop step test. The reaction curve was presented by the first order dead time model to represent the dynamic behaviour of the reactor. An Internal Model Control (IMC) system based on a non-parametric model, has been used to track the temperature of the reactor mixture. The simulation program is used to calculate the parameters of the parametric Controlled Auto Regressive Moving Average (CARMA) model for Self-Tuning PID (STPID) control. The parameters of the CARMA model are calculated using Bierman algorithm by applying Pseudo Random Binary Sequence (PRBS). In the first part of the control work, a simulation program was used to observe the performance of DVIC and STPID control systems by calculating the Integral Square Error (ISE) values. Two different kinds of operating conditions, such as load and set point effects were applied to test the control performance for servo and regulatory behaviours. The filter time τ f for IMC and the first parameter of Tailoring polynomial for STPID were used as tuning parameters. In addition, PID control system performance was compared with both parametric and non-parametric control systems. In the second part of the control work, the growth medium temperature of aerobic baker's yeast production was controlled experimentally by using IMC and STPID systems in an on-line computer controlled batch bioreactor. Non-parametric and parametric models for both control systems were tested by considering the reaction heat as a load effect. The heat input given from the immersed heater was chosen as the manipulated variable. It was observed that IMC was more effective than STPID and PID methods.