This chapter studies the problem of fault estimation using a fast adaptive fault diagnosis observer. Note that the advance of observer-based fault diagnosis is outlined and the idea of fault class estimation is introduced and studied. A new form of the estimator bloc considered for this purpose is an Unknown Input Observer (UIO). This observer is designed for an unknown input and fault free sys...

In this paper we exploit the connection between disturbance observer and L1 adaptive control theories. We consider L1 adaptive output–feedback control framework, for which the L1 reference controller is equivalent to the disturbance observer. Using this fact, we investigate several properties of the disturbance observer architecture, leading to various filter design methods towards verification...

Disturbance Observer based robot control algorithms provide good performance while giving a straightforward method of gain selection. Unfortunately, the stability of these algorithms has not been shown rigorously for nonlinear systems such as robots. This paper demonstrates that a disturbance observer based algorithm can be made equivalent to the well known passivity based approaches of Sadegh ...

"Astructural approach to the disturbance decoupling problem of non-linear systems is introduced. For this purpose, in analogy to linear systems theory, a structural description of non-linear systems is defined. In associating a directed graph to such a system, two important system properties, the differential output rank and the structure at infinity, can be characterized in terms of inputoutpu...

This work studies the problem of design of discrete-time nonlinear observers in the presence of exogenous disturbances. In particular, the present work proposes a systematic design method for discrete-time nonlinear state and disturbance observers in modular form, consisting of an observer for the disturbance-free part of the system, along with a disturbance observer and a stateestimate correct...

A robust observer-based leader-following consensus control for linear multi-agent systems subject to external disturbance and measurement noise is developed. The $$H_\infty $$ criterion implemented guarantee stability robustness of the synchronization error estimation through Lyapunov approach. set matrix inequalities are obtained compute observer gain matrices. To show its effectiveness, propo...