- Title
- Robust control of port-Hamiltonian systems
- Creator
- Ferguson, Joel
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2018
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- The port-Hamiltonian framework, which is utilised for both system modelling and control design, emphasises the role of physical energy, component interconnections and dissipation within a system's dynamic equations of motion. This work is concerned with developing control techniques for set-point regulation of physical systems within the port-Hamiltonian framework. The proposed control strategies are developed to be robust against both parametric uncertainty and external disturbances. Whilst some of the proposed results hold for general port-Hamiltonian systems, the primary focus of this work is concerned with controlling standard mechanical systems. One of the key developments of this work is the proposal of a new method to apply integral action to stable port-Hamiltonian systems. The method defines the energy associated with the integral action controller to be a function of both the plant states and the integral action states. Consequently, the proposed method avoids the use of coordinate transformations that has been pervasive in previous work on the topic. Variants of this new integral action scheme are applied throughout this thesis to robustify set-point regulating control schemes with respect to external disturbances. The set-point regulation problem is considered for two important classes of mechanical systems; fully-actuated systems and nonholonomic systems. In the case of fully-actuated systems, a new method of stabilisation is proposed that guarantees global exponential stability and input-to-state stability. The underlying principle of this approach is to generalise the structure of potential energy in closed-loop, allowing it to be a function of both configuration and momentum. This generalisation allows damping to be injected into the configuration dynamics of the system. Furthermore, the proposed construction results in a closed-loop system which is robust against uncertainty of the open-loop damping structure (friction), a quantity which is often difficult to model accurately in practice. Constructing set-point regulating control laws for a class of finite dimensional nonholonomic systems is also considered. It is shown that this problem is able to be solved using a combination of potential energy-shaping and damping injection. However, as this class of systems does not satisfy Brockett's necessary condition for smooth stabilisation, both the closed-loop potential energy function and damping structure are constructed to be discontinuous functions of the system's configuration. As is the case for the set-point regulating controller proposed for fully-actuated systems, this approach to control design is robust against uncertainty of the open-loop damping structure (friction).
- Subject
- nonlinear control; port-Hamiltonian systems; nonholonomic systems; mechanical systems
- Identifier
- http://hdl.handle.net/1959.13/1388164
- Identifier
- uon:32730
- Rights
- Copyright 2018 Joel Ferguson
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 2 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 280 KB | Adobe Acrobat PDF | View Details Download |