Hieu Trinh

State and input simultaneous estimation for a class of nonlinear systems

This paper addresses the problem of estimating simultaneously the state and input of a class of nonlinear systems. Here, the systems nonlinear part comprises a Lipschitz nonlinear function with respect to the state and input, and a state-dependent unknown function including additive disturbance as well as uncertain/nonlinear/time-varying terms. Upon satisfying some conditions, the observer design problem can be solved via a Riccati inequality or a LMI-based technique with asymptotic estimation guaranteed. A numerical example is included for illustration.

Functional observers for dynamical systems

In control theory, a state observer is an auxiliary dynamical system that mirrors the behaviour of a physical system, and it is driven by input and output measurements of the physical system in order to provide an estimate of internal states of the physical system. The primary consideration in the design of an observer is that the estimate of the states should be close to the actual value of the system states. On the other hand, the functional observation problem centers on the construction of an auxiliary dynamical system, known as the functional observer or functional reconstructor, driven by the available system inputs and outputs in order to estimate a linear function or functions of the system states. Obviously, a functional observer is a general form of the state observer because when the linear functions are chosen as the individual states of the system then the problem of functional observation reduces to the problem of state observation.

Exponential Stabilization of Neural Networks With Various Activation Functions and Mixed Time-Varying Delays

This paper presents some results on the global exponential stabilization for neural networks with various activation functions and time-varying continuously distributed delays. Based on augmented time-varying Lyapunov-Krasovskii functionals, new delay-dependent conditions for the global exponential stabilization are obtained in terms of linear matrix inequalities. A numerical example is given to illustrate the feasibility of our results.

Load-frequency control of interconnected power systems via constrained feedback control schemes

Abstract In this paper a method is presented for the derivation of output feedback and decentralized proportional-plus-integral (PI) controllers suitable for the load-frequency control of interconnected power systems. The controller design method is based on the solution of a standard state feedback optimal control problem, but with some constraints imposed on the structure of the feedback gain matrix. A two-area interconnected power system (TAIPS) is used as an example to illustrate the effectiveness of the proposed method. Simulation results show that the performances of the controllers obtained in this paper compare favourably with reported ones.

Functional Observability and the Design of Minimum Order Linear Functional Observers

The design of a minimum-order linear functional observer for linear time-invariant systems has been an open problem for over four decades. This technical note provides a solution to this problem. The technical note also introduces the concept of Functional Observability/Detectability and shows that the well-known concept of Observability/Detectability is a special case of Functional Observability/Detectability.

Discrete Wirtinger-based inequality and its application

In this paper, we derive a new inequality, which encompasses the discrete Jensen inequality. The new inequality is applied to analyze stability of linear discrete systems with an interval time-varying delay and a less conservative stability condition is obtained. Two numerical examples are given to show the effectiveness of the obtained stability condition.

On the stability of linear systems with delayed perturbations

This note presents sufficient conditions for delay-independent asymptotic stability for linear systems with delayed perturbations. These conditions are shown to be less restrictive than those reported in the literature. Numerical examples are given to illustrate the results. >

A memoryless state observer for discrete time-delay systems

This paper presents a reduced-order memoryless state observer with a /spl gamma/-stability margin (0</spl gamma/<1) for linear discrete-time systems with multiple delays in both the state and control vectors. The dynamics of the observer are derived from a set of unstable and/or poorly damped eigenvalues of the system. A simple and systematic design method is presented. A numerical example is given to illustrate the properties of the new observer and its design method.

Linear functional state observer for time-delay systems

A new linear functional state observer for time-delay systems is introduced in this paper. It is shown that the observer converges, with any prescribed stability margin, to any number of linear functionals when some conditions are met. The design procedure is simple and can be easily implemented. Numerical examples are given to illustrate the properties of the new observer and its advantages over existing observer design techniques in the literature.

Two-mode overconstrained three-DOFs rotational-translational linear-motor-based parallel-kinematics mechanism for machine tool applications

The paper introduces a family of three-DOFs translational-rotational Parallel-Kinematics Mechanisms (PKMs) as well as the mobility analysis of such family using Lie-group theory. Each member of this family has two-rotational one-translational DOFs. A novel mechanism is presented and analyzed as a representative of that family. The use and the practical value of that modular mechanism are emphasized.