Robust Controller Design and Performance Analysis of Four-Tank Coupled System

This paper is focussed on the robust controller design and performance analysis of four tank coupled system (FTCS). The FTCS is a nonlinear system with multiple-input-multiple-output (MIMO) having significant coupled dynamics. The problem of liquid level control for FTCS is considered to achieve the desired set point. First, the nonlinear model of FTCS has been linearized and levels of the tanks are controlled using three different linear control strategies. Further, a robust controller has been proposed to the FTCS nonlinear model to improve the performance using integral sliding mode approach. The robust performance of the proposed controller for FTCS has been illustrated through simulation studies. A comparative analysis has been carried out among all the controllers in the existence of FTCS parametric uncertainty and external disturbances.