The insertion of communication networks in the feedback loops of control systems is a defining feature of modern control systems. These systems are often subject to unknown inputs in a form of disturbances, perturbations, or attacks. The objective of this paper is to design and analyze an observer for networked dynamical systems with unknown inputs. The network effect can be viewed as either a ...

This paper deals with the unknown input observer (UIO) design problem for a class of linear time-delay systems. A case in which the observer error can completely be decoupled from an unknown input is treated. Necessary and sufficient conditions for the existences of such observers are present. Based on Lyapunov stability theory, thedesign of the observer with internal delay is formulated in ter...

This note presents simple methods to design fulland reducedorder proportional integral observer for unknown inputs (UI) descriptor systems. Sufficient conditions for the existence of the observer are given and proven. The observer is solvable by any pole placement algorithm, it achieves a posteriori robustness state and UI estimation versus to time varying parameters and bounded nonlinear UI. A...

We consider the Unknown Input Observer and focus on three examples found in the literature.

This paper presents multiple observer design for nonlinear chaotic systems with unknown inputs in multiple model approach. The considered unknown inputs influences the states and the outputs of the system. The main objective is to estimate the state variables as well as the unknown inputs of this system. For that, we propose the synthesis of a multiple observer based on the elimination of these...

The problem of unknown input estimation and compensation is studied for actuated nonlinear systems with noisy measurements. The proposed solution is based on high order sliding-mode differentiation and discretetime optimization technique. Accuracy of the proposed hybrid estimation scheme is evaluated and stability of the compensating mechanism is established. It is shown that the fault detectio...

Positive systems are important class of dynamic systems with impressive properties. The response of such systems to positive initial conditions and positive inputs remain in the nonnegative orthant of the state space. Although positive observers have been designed for positive systems, they are unable to estimate the states when unknown inputs or disturbances are present in the systems. This pa...

This paper presents an algebraic method to design a dynamic gain unknown input observer for linear systems with commensurate delays in state, input and output variables. Necessary and sufficient conditions for the existence of such an observer are provided as well as a constructive procedure. An example is given in order to illustrate the proposed method.

In this paper a design methodology is proposed to provide a constructive solution to the problem of designing a full order observer for linear time invariant systems subjected to unknown disturbances. Necessary conditions for existence of unknown input observers are stated and solved using generalized matrix inverse. The effect of unknown disturbance present in the system is eliminated from the...

The paper addresses an on-line, simultaneous input and parameter estimation problem for a first-order system affected by measurement noise. This problem is motivated by practical applications in the area of engine control. Our approach combines an input observer for the unknown input with a set-membership algorithm to estimate the parameter. The set-membership algorithm takes advantage of a pri...