Development of Event triggered Feed forward Control Scheme for Fed-Batch E.coli Fermentation Process

Abstract

This paper presents development of Event Triggered Feed Forward Control (ET-FFC) scheme for K12 Escherichia coli (E.coli) fermentation process. Modeling and control of E.coli fermentation is a challenging task due to strong influence of the risk factors/disturbance like variations in pH, temperature, agitator speed, substrate concentration and air flow rate on biomass yield. The main idea is to develop event triggered Feed forward control scheme to reduce the influence of known disturbance on biomass by minimizing Control Energy(CE) and Integral Square Error (ISE). Real time data of Biomass concentration, substrate feed rate and temperature are collected from the 1.5 Liter laboratory experimental Bioreactor setup. Based on the data, data-driven model based Feedback Controllers (FBC) namely Proportional Integral (PI) controller and Model Predictive controller (MPC) are designed to control Biomass concentration by manipulating substrate feed rate. In addition, Feed-Forward controller is designed for known temperature disturbance. When the temperature disturbance event is detected, FF controller takes control action to suppress its effect on yield. Finally, the closed loop performances of the E.coli fermentation process with proposed controllers are evaluated and analyzed through simulation. Further, a comparative study is carried out for the closed loop system with PI based ET-FFC and proposed MPC based ET-FFC schemes qualitatively as well as quantitatively. The results show that MPC based ET-FFC scheme provides better performances with minimum ISE over PI based ET-FFC scheme.