Theory and Applications
E-Book, Englisch, 579 Seiten, eBook
Reihe: Communications and Control Engineering
ISBN: 978-1-84628-517-2
Verlag: Springer
Format: PDF
Kopierschutz: 1 - PDF Watermark
Zielgruppe
Research
Autoren/Hrsg.
Weitere Infos & Material
Positive Real Systems.- Kalman-Yakubovich-Popov Lemma.- Dissipative Systems.- Stability of Dissipative Systems.- Dissipative Physical Systems.- Passivity-based Control.- Adaptive Control.- Experimental Results.- Erratum.
1 Introduction (P. 1)
Dissipativity theory gives a framework for the design and analysis of control systems using an input-output description based on energy-related considerations. Dissipativity is a notion which can be used in many areas of science, and it allows the control engineer to relate a set of efficient mathematical tools to well known physical phenomena. The insight gained in this way is very useful for a wide range of control problems.
In particular the input-output description allows for a modular approach to control systems design and analysis. The main idea behind this is that many important physical systems have certain input-output properties related to the conservation, dissipation and transport of energy.
Before introducing precise mathematical de.nitions we will somewhat loosely refer to such input-output properties as dissipative properties, and systems with dissipative properties will be termed dissipative systems.
When modeling dissipative systems it may be useful to develop the state-space or input-output models so that they reffect the dissipativity of the system, and thereby ensure that the dissipativity of the model is invariant with respect to model parameters, and to the mathematical representation used in the model. The aim of this book is to give a comprehensive presentation of how the energy-based notion of dissipativity can be used to establish the input-output properties of models for dissipative systems.
Also it will be shown how these results can be used in controller design. Moreover, it will appear clearly how these results can be generalized to a dissipativity theory where conservation of other physical properties, and even abstract quantities, can be handled. Models for use in controller design and analysis are usually derived from the basic laws of physics (electrical systems, dynamics, thermodynamics).
Then a controller can be designed based on this model. An important problem in controller design is the issue of robustness which relates to how the closed loop system will perform when the physical system di.ers either in structure or in parameters from the design model. For a system where the basic laws of physics imply dissipative properties, it may make sense to define the model so that it possesses the same dissipative properties regardless of the numerical values of the physical parameters.
Then if a controller is designed so that stability relies on the dissipative properties only, the closed-loop system will be stable whatever the values of the physical parameters. Even a change of the system order will be tolerated provided it does not destroy the dissipativity. Parallel interconnections and feedback interconnections of dissipative systems inherit the dissipative properties of the connected subsystems, and this simplifies analysis by allowing for manipulation of block diagrams, and provides guidelines on how to design control systems.
A further indication of the usefulness of dissipativity theory is the fact that the PID controller is a dissipative system, and a fundamental result that will be presented is the fact that the stability of a dissipative system with a PID controller can be established using dissipativity arguments. Note that such arguments rely on the structural properties of the physical system, and are not sensitive to the numerical values used in the design model.