A set of observers design to a quadruple tank process

In this paper, quadruple tank process is exploited to study different type of nonlinear observer. Indeed, from the physical model of the process, and with liquid levels measurement in the bottom of two tanks, we search to reconstruct liquid levels of the two upper ones. Three approaches are analyzed namely extended Kalman filter (EKF), high gain observer (HGO) and high gain-extended Kalman filter (HG-EKF). The behavior of estimated state, in the presence of disturbance, are provided to appropriate the feature of every observer.