Design of Controller in Double Feedback Control Loop – An Analysis with Heuristic Algorithms

Abstract

Abstract In this paper, heuristic algorithm based optimization approach is proposed to design the PID controller in Double Feedback Control Loop (DFCL) for a class of stable and unstable Single Input Single Output (SISO) process models. In this work, a three dimensional search is attempted and the heuristic algorithm is employed to find the best possible values for inner loop proportional gain (Kp1), outer loop integral gain (Ki), and derivative gain (Kd). A weighted sum of Objective Function (OF) is considered to guide the optimization search in order to attain the global best values. A comparative analysis is presented between heuristic algorithms, such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Bacterial Foraging Optimization (BFO) and Firefly Algorithm (FA). From this experimental study, it is confirmed that, FA based DFCL offers better performance in reference tracking and disturbance rejection operations with reduced error values for most of the considered process models compared with the alternatives. The statistical significance of the FA is also verified using Wilcoxon’s rank test.