2-DOF Preview Feedforward Sliding Mode Controller for the Control of Multivariable Process with Dead Time

Abstract

This paper proposes a 2-DOF preview feedforward sliding mode controller (PFFSMC), which has a combination of feedback and feedforward terms in the sliding surface, for controlling the multivariable process with dead time, for both set point tracking and disturbance rejection. The proposed controller is applied for the control of the Wood and Berry binary distillation column having the composition of top and bottom products. The performance of the 2-DOF PFFSMC is compared with that of the 1-DOF preview sliding mode controller. The proposed controller delivered better responses for set point tracking and for disturbance rejection. The performance of the proposed 2-DOF PFFSMC is compared with the other controllers reported in the literature and, it was found that there was a significant reduction in the settling time by more than 76%, without any overshoot in the closed loop response. The proposed controller was robust against ±5% parametric uncertainties in gain, time constant, and dead time when these uncertainties were considered alone and together. The stability of the proposed controller was verified using the Lyapunov stability criterion.