Authors:
Liuping Wang,
Graham C. Goodwin,
Volume: 1, Page 3341 Paper number 1247
Abstract:
In previous work we have proposed an H_2 design procedure aimed at
bringing robust control and system identification closer together by
using statistical confidence bounds. The key idea was to change the
nominal design so as to reduce the overall variability from an a-priori
specified desired performance. However, due to the choice of cost function,
the original design method did not necessarily produce a robust control
system with guaranteed stability. This paper addresses the latter problem.
First a control validation procedure is proposed based on an estimated
error bound; then the stability problem is formulated as a mixed H_2/H_(infinity)
problem. The solution to this problem is obtained in the frequency
domain using a classical algorithm due to Lawson (1961). An alternative
algorithm is also described which uses standard quadratic programming
methods. Finally a simulation example is presented which shows how
the robust design method can be used in conjunction with standard identification
procedures.
Authors:
Magnus AAkerblad,
Anders Hansson,
Bo Wahlberg,
Volume: 1, Page 3347 Paper number 9039
Abstract:
The objective of this contribution is to study how to tune PID controllers
with respect to classical step-response specifications using iterative
feedback tuning. Typically the closed-loop response is improved considerably
using only six to nine closed-loop experiments.
Authors:
Gino Favero,
Wolfgang J. Runggaldier,
Volume: 1, Page 3349 Paper number 1024
Abstract:
The solution of a stochastic control problem depends on the underlying
model, i.e., on the probability measure induced by the model. The
real world model may not be known precisely, and so one solves the
problem for a hypothetical model that induces a measure generally different
but close to the real one. We investigate two ways to derive a bound
on the suboptimality of the hypothetical optimal control when it is
used in the real problem. Both bounds are in terms of the Radon-Nikodym
derivative of the real world measure with respect to the hypothetical
one.
Authors:
John S. Baras,
Vivek S. Borkar,
Volume: 1, Page 3351 Paper number 1716
Abstract:
We propose a simulation-based algorithm for learning good policies
for a Markov decision process with unknown transition law, with aggregated
stated. The state aggregation itself can be adapted on a slower time
scale by an auxiliary learning algorithm. Rigorous justifications
are provided for both algorithms.
Authors:
Charles Marchetti,
Volume: 1, Page 3357 Paper number 73
Abstract:
We Study a degenerate nonlinear optimal stochastic control problem
with finite horizon ([2]), [8] and [9]). Using the Hamilton-Jacobi-Bellman
equation, we find an asymptotic expansion for this solution of this
problem
Authors:
Rolf Johansson,
Anders Robertsson,
Volume: 1, Page 3363 Paper number 1280
Abstract:
This paper presents theory and algorithms for covariance analysis and
stochastic realization without any minimality condition imposed. Also
without any minimality conditions, we show that several properties
of covariance factorization and positive realness hold. The results
are significant for validation in system identification of state-space
models from finite input-output sequences. Using the Riccati equation,
we have designed a procedure to provide a reduced-order stochastic
model that is minimal with respect to system order as well as the number
of stochastic inputs thereby avoiding several problems appearing in
standard application of stochastic realization to the model validation
problem. The case considered includes the problem of rank-deficient
residual covariance matrices, a case which is encountered in applications
with mixed stochastic-deterministic input-output properties as well
as for cases where outputs are linearly dependent, thus extending previous
results in covariance analysis.
Authors:
Hong Wang,
Volume: 1, Page 3369 Paper number 1449
Abstract:
Following the recently developed algorithms for the control of the
shape of the output probability density function for general dynamic
stochastic systems (Wang, 1998; 1999 and 2000), this paper presents
the modelling and control algorithms for pseudo ARMAX systems, where
different from all the existing ARMAX systems the considered system
is subjected to any arbitrary bounded random input and the purpose
of the control input design is to make the output probability density
function of the system output as close as possible to a given distribution
function. At first, the relationship between the input noise distribution
and the output distribution is established via linear B-spline approximations.
This is then followed by the description on the control algorithm design
and discussions on control of unstable systems and nonlinear ARMAX
systems.
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