144 research outputs found
Control Structure Assessment in an Industrial Control System
This paper describes the implementation of a structure assessmentmethod in an industrial control system. The method uses available signals to evaluate if a given signal can be used for additional feed forward control action to improve the performance of a control loop
State-space approximation of multi-input multi-output systems with stochastic exogenous inputs
AbstractInstead of the usual AR(MA)X- or VAR (vector autoregressive) modelling, procedures will be described to obtain approximate balanced state-space models and steady-state Kalman filters with prewhitened inputs. These state-space models and Kalman filters can be used for prediction and also for control whenever the output and input variables are target and control variables respectively
Balanced realizations of discrete-time stable all-pass systems and the tangential Schur algorithm
In this paper, the connections are investigated between two different
approaches towards the parametrization of multivariable stable all-pass systems
in discrete-time. The first approach involves the tangential Schur algorithm,
which employs linear fractional transformations. It stems from the theory of
reproducing kernel Hilbert spaces and enables the direct construction of
overlapping local parametrizations using Schur parameters and interpolation
points. The second approach proceeds in terms of state-space realizations. In
the scalar case, a balanced canonical form exists that can also be parametrized
by Schur parameters. This canonical form can be constructed recursively, using
unitary matrix operations. Here, this procedure is generalized to the
multivariable case by establishing the connections with the first approach. It
gives rise to balanced realizations and overlapping canonical forms directly in
terms of the parameters used in the tangential Schur algorithm
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Strong stability of discrete-time systems
The paper introduces a new notion of stability for internal (state-space) autonomous system descriptions in discrete-time, referred to as strong stability which extends a parallel notion introduced in the continuous-time case. This is a stronger notion of stability compared to alternative definitions (asymptotic, Lyapunov), which prohibits systems described by natural coordinates to have overshooting responses for arbitrary initial conditions in state-space. Three finer notions of strong stability are introduced and necessary and sufficient conditions are established for each one of them. The class of discrete-time systems for which strong and asymptotic stability coincide is characterized and links between the skewness of the eigen-frame and the violation of strong stability property are obtained. Connections between the notions of strong stability in the continuous and discrete-domains are briefly discussed. Finally strong stabilization problems under state and output feedback are studied. The results of the paper are illustrated with a numerical example
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