Abstract— This paper addresses fault diagnosis for observerbased residual generators for linear discrete-time systems subject to unknown input. The proposed approach is a new method allowing to characterize a class of unknown inputs from which the estimation error is decoupled. This contribution is divided into two parts. The first one concerns the design of the UIO satisfying either an exact d...

non-fragile observer design is the main problem of this paper. using continuous frequency distribution, the stability conditions based on integer order lyapunov theorem are derived for lipschitz class of nonlinear fractional order systems. the proposed observer is stable beside the existence of both gain perturbation and input disturbance. for the first time, in this paper a systematic method i...

This paper deals with the design of quadratic and higher order normal forms for the left invertibility problem. The linearly observable case and one-dimensional linearly unobservable case are investigated. The interest of such a study in the design of a delayed discrete-time observer is examined. The example of the Burgers map with unknown input is treated and a delayed discrete-time observer i...

In order to solve the fault detection and isolation problem, a diagnostic procedure is used. This procedure is composed of two steps: residuals generation followed by their evaluation within decision functions. Many ways have been developed to generate residuals. Among them, we quote the well known parity space approach and the observer based approach. These methods are known to produce structu...

In the presence of unknown time-varying disturbances and input saturation, this paper develops a robust nonlinear control law for the dynamic positioning (DP) system of ships using a disturbance observer, an auxiliary dynamic system, and the dynamic surface control (DSC) technique. The disturbance observer is constructed to provide the estimates of unknown time-varying disturbances, the auxilia...

This paper presents a diagnosis scheme based on a linear matrix inequality LMI algorithm for incipient faults in a nonlinear system class with unknown input disturbances. First, the nonlinear system is transformed into two subsystems, one of which is unrelated to the disturbances. Second, for the subsystem that is free from disturbances, a Luenberger observer is constructed; a sliding mode obse...

This paper uses a new position sensor less drive for brushless DC (BLDC) motors. In conventional sensor less control methods such as the back-EMF detection method, the performance is high only at a high speed range due to the fact that the magnitude of the back-EMF is dependent on the rotor speed. A solution is derived that estimates the rotor position by using an unknown input observer over a ...

The aim of this investigation is to construct an adaptive observer and an adaptive compensator for a class of infinitedimensional plants having a known exogenous input and a structured perturbation with an unknown constant parameter, such as the case of static output feedback with an unknown gain. The adaptive observer uses the nominal dynamics of the unperturbed plant and an adaptation law bas...

The problem of unknown input observer design for non-linear Lipschitz systems is considered. A new dynamic framework which is a generalization of previously used linear unknown input observers is introduced. The additional degrees of freedom offered by this dynamic framework are used to deal with the Lipschitz non-linearity. The necessary and sufficient condition that ensures asymptotic converg...

In this paper, any unknown input observers with orders between minimum and full orders can be established for singular systems by eigenstructure assignment method. The complete and parametric solutions for the observer matrices and for the generalized eigenvectors are obtained. The completeness and parametric forms of the solutions and the flexibility in selecting the observer order allow the d...