Output feedback controller of a multivariable process

The incorporation of an observer into a state feedback controller results into the so-called output feedback controller. Due to its easiness of design and implementation, many control strategies were reformulated under output feedback. This paper deals with the control problem of a MIMO process represented by a quadruple tank process through the use of a recently proposed output feedback controller. Such one is based on the use of a high gain observer which we propose to substitute with a sliding mode observer. Numerical simulations are developed to show the effectiveness of the proposed observer when applied to estimate the water levels into two bottom tanks. Into the control law is incorporated a filtered integral action. The effectiveness of such component is showed when we evaluate the robustness of the whole process against step like disturbances and stochastic noises.