OPTIMIZED SLIDING MODE CONTROLLER FOR A CLASS OF TITO PROCESS WITH INTERACTION

Abstract

Control of Multi Input Multi Output (MIMO) process possessing interaction is a common problem in the field of process control. This paper is about the design of Sliding Mode Controller (SMC) for the control of Two Input - Two Output (TITO) process with elements of process transfer function matrix represented as First Order plus Dead Time (FOPDT) model. The conventional SMC designed delivered poor control performance, when applied for the control of TITO process, for the case where the ratio of dead time and time constant of the FOPDT model in the process transfer function matrix is greater than one. Interestingly, in the design of SMC, if the discontinuous part of SMC is multiplied by a weighting factor, the controller performance improved. In this work, Genetic Algorithm and Simulated Annealing optimization techniques are employed to find the best value of the weighting factors. The SMC thus designed delivered better closed loop performance, when applied for the control of different TITO processes, when compared to the results found in the literature.