In this paper presents a noval approach to design of PID controller for two input two output (TITO) system using Particle Swarm Optimization (PSO) technique. The PSO technique is used to find the global optimum values of PID parameters for TITO processes which help in easy implementation, stable convergence characteristic, better computational efficiency and fast tuning of process .In order to maintain estimating the performance of the proposed controller, a new time-domain performance index was also defined i.e. Integral square error (ISE).The analysis and procedure are illustrated through simulation for TITO processes.
Keywords -Proportional-integral derivative (PID) controller, Particle swarms optimization (PSO), Two-input two-output (TITO) system, Integral square error (ISE).
I. INTRODUCTIONIn the chemical and process industries decentralized PID control is one of the most popular control schemes for interacting multiple-input multiple output (MIMO) plants. The main reason to use this controller is to simple, give good performance and easy to implementation for wide range of process. The tuning of controller in MIMO plant is more complicated because of the interactions between loops. A small change in one loop affects the other loop. Many researchers have addressed about the decentralized PID controllers tuning for MIMO processes[2-10].The most well known method for PID tuning for single-input single-output (SISO) is Ziegler-Nichols(ZN) method in 1942 [1]. In this method various instructions are proposed for tuning the PID controller parameters. The method of Niederlinski (1971) [2] is a more natural extension of the ZN tuning procedure of the MIMO processes. Marino-Gallarraga et al. (1987) [3] presented a design method that combines information regarding the MIMO system performance and SISO properties of each loop. The-BLT-(biggest log modulus tuning) method (Luvben. 1986) [4] also aims at tuning decentralized PID controllers. Design of multi-loop controller is numerically difficult. Lately, Wang et al. [5] presented a controller design method for MIMO system. Astrom and Hagglund [6] introduced the relay autoprocess for identification of unknown process dynamics.. Several approaches have been proposed for identification in the literature in order to get good responses for significant loop interaction. One approach is to develop a full matrix transfer function model for the process 1,