Employing disturbance observers is an effective way of enhancing the stability and performance of the control systems subject to disturbances. Disturbance observers have been extensively used for control of mechatronic systems since their introduction in the 1980s. This thesis studies the design of nonlinear disturbance observers for robotic manipulators and their applications in the control of...

This paper deals with the design of adaptive observers that can estimate both the states and the parameters of a large class of nominal and perturbed nonlinear systems with a regression matrix (i.e. matching matrix with the unknown parameter vector) depending on unknown states. The asymptotic stability of the state and parameter estimate errors is developed in the presence of common persistency...

In this work, the problem of designing observers for estimating a single nonlinear functional state is formulated general systems. Notions observer linearization are also formulated, in terms achieving exactly linear error dynamics transformed coordinates and with prescribed rate decay error. Necessary sufficient conditions existence lower-order derived. The results provide direct generalizatio...

Recently there has been an intense activity in designing observers by means of the circle criterion. However, it is known that the use of Popov’s criterion reduces the conservativeness of stability analysis based on the circle criterion, if further restrictions are satisfied by the nonlinearity. It is shown in this paper that Popov’s criterion can indeed be used with advantage for observer desi...

Nonlinear observers for estimation of lateral and longitudinal velocity of automotive vehicles are proposed. The observers are based on a sensor suite that is standard in many new cars, consisting of acceleration and yaw rate measurements in addition to wheel speed and steering angle measurements. Two approaches are considered: first, a modular approach where the estimated longitudinal velocity...

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau...

Preserving Order Observers provide an estimation that is always above or below the true variable and, in the absence of uncertainties/perturbations, the estimation converges asymptotically to the true value of the variable. In this paper we propose a novel methodology to design preserving order observers for a class of nonlinear systems in the nominal case or when perturbations/uncertainties ar...

In this paper we begin by assuming that an observer with a corresponding quadratic-type Lyapunov function has been designed for a given nonlinear system. We then consider the problem that arises when the output of that nonlinear system is not directly available; instead, it acts as an input to a second, linear system from which a partialstate measurement is in turn available. We develop an obse...