Authors:
Igor Mezić,
Andrzej Banaszuk,
Volume: 1, Page 1224 Paper number 4801
Abstract:
We present a formalism for comparing the asymptotic dynamics of dynamical
systems with physical systems that they model. There is often no need
for the detailed (trajectory-wise) comparison of a dynamical system
and the physical system that it models, but only comparison in statistical
sense. For that purpose, invariant measures are typically considered.
But, invariant measures usually can not be observed directly in an
experiment. Thus, we base our formalism on time-averages obtained from
a single observable. In particular, we constructively prove that,
generically, a single observable is needed in order to recover an invariant
ergodic measure. Pseudometrics on space of dynamical systems can be
defined using this formalism in order to compare their statistical
behavior. We also identify the need to go beyond comparing only invariant
ergodic measures of systems and introduce an ergodic-theoretic treatment
of a class of spectral functionals that allow for this. The formalism
is extended for a class of stochastic systems: discrete Random Dynamical
Systems. The ideas introduced in this paper can be used for parameter
identification and model validation of driven nonlinear models with
complicated behavior. As an illustration we provide an example in which
we compare the asymptotic behavior of a combustion system measured
experimentally with the asymptotic behavior of the model that is a
stochastic control dynamical system.
Authors:
Roy S. Smith,
Geir Dullerud,
Scott A. Miller,
Volume: 1, Page 1232 Paper number 4802
Abstract:
Model validation provides a useful means of assessing the ability of
a model to account for a specific experimental observation, and has
application to modeling, identification and fault detection. In a
robust control framework norm-bounded perturbations are included to
account for dynamic uncertainties in the system. We consider a discrete-time
or sampled-data framework with a general linear fractional transformation
(LFT) model structure which allows for the consideration of nonlinear
feedback structures. Block structured, causal , time-varying perturbations
are considered and we give a sufficient condition---necessary and sufficient
in the single perturbation block case---for the model to be invalidated
by the datum. The condition is testable by a convex LMI feasibility
problem in which the matrix basis grows linearly in size with respect
to the data length and the number of decision variables is equal to
the number of perturbation blocks.
Authors:
Wayne J. Dunstan,
Robert R. Bitmead,
Sergio M. Savaresi,
Volume: 1, Page 1237 Paper number 4803
Abstract:
This paper details an example of experiment design for validation of
a nonlinear model arising in the limit cycling behavior of lean, premixed
combustion. The validation problem is important because of the poor
information content of the periodic limit cycle data and the challenge
is to provide a practically feasible, small excitation to the loop
to improve identifiability and to provide qualitative tests of model
performance. We examine this problem by considering the nonlinear dynamics
of the model class and feasible excitation mechanisms.
Authors:
Robert L. Kosut,
Volume: 1, Page 1243 Paper number 4804
Abstract:
In this paper we pursue the idea that adaptive linear control can be
used to nullify (possibly) deleterious effects of unknown nonlinearities.
The design approach is based on ideas of direct controller falsification.
An example is presented which shows control of a nonlinear systems
which exhibits multi-periodic and chaotic behavior.
Authors:
Mareike Claassen,
Eric Wemhoff,
Andrew Packard,
Kameshwar Poolla,
Volume: 1, Page 1248 Paper number 4805
Abstract:
In this paper we investigate the problem of identifying static nonlinear
maps as part of a general, structured interconnected system. The static
nonlinear maps that require identification are not naturally parameterized
via basis functions or other expansions. Thus, we are interested in
non-parametric identification of these nonlinear maps. The particular
focus of this paper is the issue of ``identifiability''. Loosely speaking,
the static nonlinear maps in an interconnected system are identifiable
if it is possible to determine them uniquely on the basis of input-output
experiments. As is well known, identifiability concepts are of fundamental
importance in system identification. In this paper, we focus on the
case where only the static nonlinearity needs to be identified and
the linear components of the interconnection are known. We offer a
readily computable test for identifiability in the case that the inputs
to every nonlinear map are measured. This test reduces to a matrix
positivity computation.
Authors:
Benoit David,
Georges Bastin,
Volume: 1, Page 1254 Paper number 4806
Abstract:
This paper addresses the problem of estimating, from measurement data
corrupted by highly correlated noise, the shape of an unknown scalar
and univariate function hidden in a known phenomenological model of
the system. The method makes use of the Vapnik's support vector regression
to find the structure of a parametrized black box model of the unknown
function. Then the parameters of the black box model are identified
using a maximum likelihood estimation method specially well suited
to cope with correlated noise. The ability of the method to provide
an accurate confidence bound for the unknown function is clearly illustrated
from a simulation example.
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