GA-Based Design of a Two-Degree-of-Freedom PID Controller for an Injera Cooking Machine

Abstract

Ethiopians eat Injera as their main meal, and many households use Injera Cooking Machine for baking Injera; maintaining the temperature of the Injera Cooking Machine (ICM) constant as the cooking temperature affects the taste and quality of cooked Injera. The two critical aspects in designing a temperature controller for Injera Cooking Machines are setpoint tracking and disturbance rejection. The setpoint tracking control tracks the setpoint when the ICM is raised to a cooking temperature at the start without giving excessive thermal stress. The disturbance rejection control keeps the cooking temperature constant. The adopted ON and OFF temperature control mechanism results in temperature fluctuation around the setpoint. Solving this problem with the existing one-degree-of-freedom (1DOF) PID controller cannot simultaneously enhance setpoint tracking and disturbance rejection performance. The thesis addresses the design of a two-degree-of-freedom PID (TDOF PID) controller incorporated with an Anti-Windup scheme and a Genetic Algorithm (GA) for simultaneous setpoint tracking and disturbance rejection response. The Anti-Windup technique reduced the error caused by Integral Windup, and GA estimates the system model parameters and tune controller parameters. An experimental setup incorporated with data acquisition obtains the system's actual response for subsequent use in model parameter estimation and model validation. The GA estimated model parameters has a +90% percentage fitting with the actual measured response, and the proposed controller simultaneously tracks the optimal cooking temperature and rejects the disturbance compared to 1DOF PID controllers with zero-percentage overshoot (Mp=0%), settling time(ts=7.632-min), and recovery time (trcy=13.592-min). The Anti-Windup scheme eliminates the significant overshoot (Mp>20%) caused by the Integral Windup to zero percent (Mp=0%) with a faster settling time. The proposed controllers remove temperature fluctuation caused by the ON and OFF controllers and can replace the existing ON and OFF controller adopted in the current Injera Cooking Machine. Furthermore, the thesis supports the research gap on temperature controller design for ICM