Hybrid observer design is addressed for a class of discrete-time linear switched systems whose switching mechanism is unknown. The hybrid observation problem consists in determining the estimation of the current mode and the continuous observer for continuous behavior from a finite set of input-output data. First, the current mode is estimated using a classification algorithm that associates th...

In this paper we propose a general method to estimate periodic unknown input signals of finitedimensional linear time-varying systems. We present an infinite-dimensional observer that reconstructs the coefficients of the Fourier decomposition of such systems. Although the overall system is infinite dimensional, convergence of the observer can be proven using a standard Lyapunov approach along w...

In this paper, we propose a discrete-time nonlinear sliding mode observer for state and unknown input estimations of a class of single-input/single-output nonlinear uncertain systems. The uncertainties are characterized by a state-dependent vector and a scalar disturbance/unknown input. The discrete-time model is derived through Taylor series expansion together with nonlinear state transformati...

The purpose of the paper is to present an approach to detect, isolate and accommodate the sensor or actuator faults using bank of observer and unknown input observers (UIO). Full order observers, reduced order observers, unknown input observers and Kalman Filter are widely used in state estimations [1]. After the estimation of states, fault detection and isolation can be provided by conducting ...

This paper investigates the velocity-free feedback control problem associated with finite time attitude stabilization of a rigid spacecraft subject to external disturbance and input saturation. First of all, to address the lack of angular velocity measurement, a novel, fast, finite time convergent observer is proposed to recover the unknown angular velocity information in a finite time under ex...

This paper focuses on the use of unknown input observers for detection and isolation of actuator and effector faults with control reconfiguration in overactuated systems. The proposed approach consists in tuning the observer parameters in order to make the filters decoupled from faults affecting selected groups of actuators or effectors. The control allocation actively uses input redundancy in ...

This paper presents an efficient proportional-plus-integral (PI) current-output observer-based linear quadratic discrete tracker (LQDT) design methodology for the non-minimum-phase (NMP) discrete-time system with equal input and output number, for which the minimalized dynamic system contains the unmeasurable system state and unknown external matched/mismatched input disturbances. Illustrative ...