Authors:
Stuart Crawshaw,
Glenn Vinnicombe,
Volume: 1, Page 1063 Paper number 9907
Abstract:
We consider the problem of anti-windup compensation based on coprime
factorizations, for asymptotically stable plants with an input saturation
nonlinearity. Firstly, we state a stability criterion for the nonlinear
system which guarantees finite-gain L2 stability. Then we propose an
H-infinity-based synthesis method which is guaranteed a priori to stabilize
the system with a guaranteed level of L2 performance.
Authors:
Richard G. Ford,
Keith Glover,
Volume: 1, Page 1069 Paper number 1652
Abstract:
This paper presents an application of the coprime factor based anti-windup
technique of Miyamato and Vinnicombe [MV96]. The application is an
automotive engine idle speed control problem using a novel framework
which inverts most of the system nonlinearities. A discussion of the
design procedure is given, and extensions to the technique are developed
to enable implementation. The final controller is implemented in the
Matlab/dSPACE rapid prototyping suite and is used to control a 1.8l
spark ignition engine. Results for both anti windup and bumpless transfer
situations are presented and discussed.
Authors:
Wolfgang Reinelt,
Volume: 1, Page 1075 Paper number 1217
Abstract:
We determine the maximum output amplitude of a system, when the input
is bounded by certain constraints. In particular, amplitude and rate
of change (i.e. the first derivative) have to be bounded. We show
properties of the worst case input and present an algorithm that allows
construction of this input and calculates the maximum amplitude of
the output. The solution of this problem is a necessary and important
step within a couple of recently developed controller-design procedures,
dealing with plants with hard-bounded inputs. Nevertheless, it is
interesting as a system theoretic task itself and therefore stated
separately.
Authors:
Matthew C. Turner,
Ian Postlethwaite,
Volume: 1, Page 1081 Paper number 1627
Abstract:
Due to the conservatism of the conventional, or affine, Small Gain
Theorem, in some situations its use may not give an accurate indication
of the true performance achievable in a given system. This is especially
true of certain feedback loops with saturation elements present. Here,
the recently derived monotone Small Gain Theorem is discussed with
respect to these types of system, and it is shown how certain constructions
of feedback will guarantee global stability of the interconnection.
This result is then applied to two instances where this type of configuration
naturally occurs: anti-windup compensation and systems with ``soft''
output constraints.
Authors:
Baltazar Aguirre,
Carlos Ibarra,
Rodolfo Suárez,
Volume: 1, Page 1087 Paper number 1722
Abstract:
In [Hinrichsen, D. and Kharitonov, V. L., 1995], a necessary and sufficient
conditions for a convex conic set of polynomials to be Hurwitz was
given. However, that result is not simple to apply. In this paper,
an easy-to-check sufficient condition is introduced. The obtained condition
is a matrix inequality which is a simple algebraic test for the stability
of rays of polynomials. As an application, for stable open-loop systems,
a cone of gains c such that the function u=-kc^Tx is a stabilizing
control feedback for all k>0, is shown to exist. Moreover, for the
same cone of gains, it was established that there do not exist any
first harmonic periodic orbits despite saturation.
Authors:
Jonathan Paxman,
Glenn Vinnicombe,
Volume: 1, Page 1093 Paper number 1909
Abstract:
In this paper, we develop two general schemes for reducing the performance
degradation caused by a signal substitution at the plant input. Such
substitutions arise in modern control systems where we may transfer
from manual to automatic, or between alternative controllers as operating
points or performance criteria change. The problem reduces to the selection
of the initial controller state for the controller which is to be switched
in. The first scheme selects a controller state consistent with (hypothetical)
signals at the plant input and output which are close (in the sense
of a weighted 2-norm) to observed signals. The second scheme (for
regulator and step reference problems) minimises directly the weighted
plant input and output after the switch with respect to the controller
initial state. We consider these schemes in the context of the regulator
problem, and the reference tracking problem.
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