Robust Control of Coupled-Tank System using Uncertainty and Disturbance Estimator

In this paper, an uncertainty and disturbance estimator (UDE) based control method has been proposed for the control of liquid level of coupled-tank system which is extensively used in process industry. The objective of this study is to control the water level of the tank system with minimum setting time and zero steady state error. The desired transient and steady-state response specifications are expressed by a reference model. The system with designed UDE tracks the desired trajectory of liquid level perfectly. The controller also gives satisfactory responses in presence of disturbance and parameter variations. The performances of the UDE and proportional-integral-derivative (PID) controller have been compared. It has been observed that UDE based control law gives better performance than PID.