A novel method for generating q-Markov covers for SISO (single-input single-output) discrete-time systems is proposed. It is based on first computing the impulse-response Gramian from the Markov parameters and covaria...
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A novel method for generating q-Markov covers for SISO (single-input single-output) discrete-time systems is proposed. It is based on first computing the impulse-response Gramian from the Markov parameters and covariances, and then solving the Lyapunov equation inversely to get the system matrices in controllability canonical form. Given the markov parameters and the covariances, exactly two q-Markov covers can be obtained by solving the Lyapunov equation inversely to get the system matrices. The method is illustrated by a numerical example and is shown to be computationally simple.< >
The asymptotic tracking properties of an adaptive notch filter with pole-zeros constraints for the cancellation or retrieval of multiple time-varying sine waves in additive noise are analyzed. The methods of Ljung and...
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The asymptotic tracking properties of an adaptive notch filter with pole-zeros constraints for the cancellation or retrieval of multiple time-varying sine waves in additive noise are analyzed. The methods of Ljung and Gunnarsson (see automatica, vol.26, no.1, p.7-21, Jan. 1990) are used in order to analyze the asymptotic mean-square parameter error, when the variations in the underlying frequencies and the gain of the algorithm are assumed to be sufficiently small. A closed-form expression for the mean square error (MSE) is derived as a function of the tuning variables of the algorithm. The results give insight into the operational properties of the algorithm and are used in order to minimize the MSE with respect to the tuning variables.< >
This paper treats the problem of on-line identification of systems with varying delay, based on measurements of the input and output signals. A discrete rational delay approximation is used in a process model. The loc...
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This paper treats the problem of on-line identification of systems with varying delay, based on measurements of the input and output signals. A discrete rational delay approximation is used in a process model. The local minima of a specified loss function are analysed and the choice of design variables is discussed. A simulation example of the identification of a system with variable delay is presented. Simulation results indicate that a model that includes a discrete delay approximation can successfully be used for estimation of both time-delay and dynamics of a system.
Algebraic necessary and sufficient conditions for the stability analysis of 2-D discrete systems are presented. These conditions are developed based on the frequency-dependent formulation of the Lyapunov equation usin...
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Algebraic necessary and sufficient conditions for the stability analysis of 2-D discrete systems are presented. These conditions are developed based on the frequency-dependent formulation of the Lyapunov equation using Kronecker products. It is shown that these necessary and sufficient conditions for internal stability of 2-D discrete systems are equivalent to testing the eigenvalues of constant matrices. This is a simplification over earlier tests which require testing the positivity of one or more functions of omega for all omega epsilon (0,2 pi ).< >
The necessary and sufficient conditions for the existence of positive definite solutions for the 2-D Lyapunov equation for 2-D discrete, 2-D continuous, and differential-delay systems are presented. It is shown that t...
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The necessary and sufficient conditions for the existence of positive definite solutions for the 2-D Lyapunov equation for 2-D discrete, 2-D continuous, and differential-delay systems are presented. It is shown that these conditions are related to the strictly positive real and strictly bounded real conditions. The relationship between these conditions and the stability ones is also discussed.< >
A robust control scheme for the output tracking of SISO (single input, single output) nonlinear systems is proposed. The scheme is based on the nonlinear regulator theory and the sliding mode approach. The basic idea ...
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A robust control scheme for the output tracking of SISO (single input, single output) nonlinear systems is proposed. The scheme is based on the nonlinear regulator theory and the sliding mode approach. The basic idea consists of designing a nonlinear regulator-based controller and then modifying it by defining a subset of the state space, called a sliding surface, on which the tracking error goes asymptotically to zero. It is found that, under certain conditions, the sliding controller forces the system to reach the sliding surface when perturbations on the plant occur, hence obtaining a tracking error that, in the mean, asymptotically tends to a sufficiently small region around zero. An illustrative example is given.< >
A general state-space model of a two-dimensional linear multivariable discrete system was introduced by Kurek [1]. This model includes the 2-D models of Attasi [2], Roesser [3], and Fornasini and Marchesini [4]. In th...
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A general state-space model of a two-dimensional linear multivariable discrete system was introduced by Kurek [1]. This model includes the 2-D models of Attasi [2], Roesser [3], and Fornasini and Marchesini [4]. In this paper, a novel approach for computing the transfer function, the characteristic polynomial, and the adjoint matrix of the Kurek model is given. The procedure involves representation of the system characteristic equation in a matrix polynomial.
A novel piecewise linear model of the magnetic characteristics of a switched-reluctance motor is formulated and the procedure to evaluate the model parameters is illustrated. On the basis of the model, the torque-posi...
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A novel piecewise linear model of the magnetic characteristics of a switched-reluctance motor is formulated and the procedure to evaluate the model parameters is illustrated. On the basis of the model, the torque-position and average torque equations of the motor are calculated and expressed in a normalized form. A significant figure related to the motor performance is then introduced and discussed. The merit of the model over the existing ones in providing accurate results without complicating the analysis is pointed out.
The problem of estimating autoregressive moving average ARMA models for narrowband processes is considered. The following approach is proposed. Estimate a high-order autoregressive (AR) approximation of the process. B...
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The problem of estimating autoregressive moving average ARMA models for narrowband processes is considered. The following approach is proposed. Estimate a high-order autoregressive (AR) approximation of the process. By model reduction, based on a truncated internally balanced realization or optimal Hankel-norm model reduction, reduce the order of this high-order AR estimate to find a lower-order ARMA model. This algorithm gives ARMA spectral estimates with excellent resolution properties, without using iterative numerical minimization methods as for the maximum-likelihood method. How to take the narrowband assumption into account in the model reduction step is discussed in detail.
To track the time-varying dynamics of a system or the time-varying properties of a signal is a fundamental problem in control and signal processing. Many approaches to derive such adaptation algorithms and to analyse ...
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To track the time-varying dynamics of a system or the time-varying properties of a signal is a fundamental problem in control and signal processing. Many approaches to derive such adaptation algorithms and to analyse their behaviour have been taken. This article gives a survey of basic techniques to derive and analyse algorithms for tracking time-varying systems. Special attention is paid to the study of how different assumptions about the true system's variations affect the algorithm. Several explicit and semi-explicit expressions for the mean square error are derived, which clearly demonstrate the character of the trade-off between tracking ability and noise rejection.
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