Evolutionary Algorithm Based Robust Fixed Structure Controller for pH in Sodium Chlorate Process

Abstract

PID Controllers are used in almost 95% of control loops in the most process industry. Since the design of a controller for an industrial system is complex due to the presence of model uncertainties, nonlinearities, and disturbances, these controllers are usually not tuned optimally and performance is compromised. Robust fixed structure control is a remedy to the problem, and such a controller design is an optimization problem, characterized by nonlinear multimodal large pursuit space, tight constraints, and expensive objective function. The classic optimization method is not appropriate here as a solution set is to be computed. Evolutionary algorithm, a robust search, and optimization method can handle this problem. Covariance Matrix Adapted Evolutionary strategy is successfully utilised to design robust PID controller for Sodium chlorate process. The performance in terms Integral Square Error (ISE) for set point tracking, robust stability and disturbance attenuation was found satisfactory.