Abstract: The objective of this paper is to design a robust controller for the wet end of a paper making machine. The controlled variables are ash content, basis weightand manipulated variable are filler flow rate and thick stock flow rate. This paper includes a mathematical multivariable model and presents a Linear Quadratic Gaussian (LQG) controller design for this system. For LQG, the filler flow rate acting as a disturbance. In this paper, Simulation results conclude that the stability & performance of robust controller is better than that of the PID controller in the presence of uncertainty & disturbances.

Keywords: Wet end of paper machine, Linear Quadratic Gaussian, Kalman filter, state space model.