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by Chen Xi. / "July 2000." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. 107-112). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Zhang Li. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 67-69). / Abstracts in English and Chinese. / Chapter 1 --- Introduction and Literature Review --- p.1 / Chapter 2 --- The Tracking Portfolio Models --- p.7 / Chapter 2.1 --- Problem Formulation --- p.8 / Chapter 2.2 --- Reformulation of Tracking Models --- p.12 / Chapter 2.3 --- A Stochastic LQ Control Approach --- p.13 / Chapter 3 --- Efficient Tracking: Deterministic Market Parameters --- p.16 / Chapter 3.1 --- Solution to Model I --- p.17 / Chapter 3.2 --- A Special Case of Model I --- p.23 / Chapter 3.3 --- Solution to Model II --- p.24 / Chapter 3.4 --- A Special Case of Model II: Mean-Variance Portfolio Selection --- p.32 / Chapter 3.5 --- Solution to Model III --- p.36 / Chapter 4 --- Efficient Tracking: Markov-Modulated Market Parameters --- p.41 / Chapter 4.1 --- Problem Formulation --- p.42 / Chapter 4.2 --- Solution to Model I with Regime Switching --- p.47 / Chapter 4.3 --- Solution to Model II with Regime Switching --- p.52 / Chapter 4.4 --- Solution to Model III with Regime Switching --- p.59 / Chapter 5 --- Conclusion --- p.64 / Bibliography --- p.66

In maintaining power system stability; especially that of large interconnected systems, in the face of large disturbances it is desirable to have a non-linear control technique that is simple and inexpensive to implement. This thesis presents a non-linear control technique which relies on angle measurements taken at strategic points in the power system with the aid of the G.P.S. ( Global Positioning System ) timing signal. A method for estimating these bus angles which is faster than previous methods is developed as well as a technique for choosing the locations of these transducers. This transducer placement algorithm aims to place transducers at locations whose bus voltage response to the less well damped inter-area modes is maximised and whose response to the better damped local modes is minimised. Since the control techniques are based on aggregated classical models of coherent generators it is important to be able to estimate the internal voltages of these aggregate machines. The placement algorithm ensures maximally precise angle estimates in the presence of noise by minimising the condition number of the observation matrix relating transducer bus voltages to internal aggregated machine voltages. The non-linear control techniques presented rely on an energy function developed in this thesis which is based on the physical circuit energy of the system. One technique; the Direct Energy technique looks at maximising the negativity of the time rate of change of the energy function, assuming that the energy function is positive during the time frame of interest. It is shown that should the number of controllers be less than the number of modes, excluding the centre of area mode, then sustained oscillations appear which will only be damped by the natural damping of the system. This may be overcome by using techniques which rely on reducing the entire system energy over the time frame of interest. These so-called Lookahead techniques can rely on higher order time derivatives of the energy function or on co-states, the latter being the principal focus of this thesis. The Lookahead control technique developed is based on co-states which are estimated by the using the solution to the time independent Ricatti equation for a LQ model of the system. It is shown to produce good damping in a number of case studies. Furthermore it is shown to perform well in the presence of both static and dynamic load models. Also it is shown that the path dependent terms introduce some ambiguity as to whether or not the system will converge to a stable equilibrium point. It is shown that it is possible to put a bound on the region to which the power system can be assured to converge. Furthermore the addition of the above-mentioned control strategies has the effect of overcoming the effect of the path dependent terms and, should the control action be strong enough, completely swamping them and ensuring system convergence to a stable operating point. In any case the energy function could be directly monitored since all the data needed is being collected anyway for control purposes. / PhD Doctorate

Thesis (MScIng)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on July 18, 2008) Vita. Includes bibliographical references.

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The use of rotary winged unmanned aerial vehicles in military and civilian applications is rapidly increasing. The primary objective of this study is to develop an automatic flight control system for a radio controlled (RC) helicopter. There is a need for a simple, easy to use methodology to develop automatic flight controllers for first-flight. In order to make the work accessible to new research groups without physical helicopter platforms, a simulation environment is created for validation. The size 30 RC helicopter in AeroSIMRC is treated as the final target platform. A grey box, timedomain system identification method is used to estimate a linear state space model that operates around hover. Identifying the unknown parameters in the model is highly dependent on the initial guess values and the input data. The model is divided into subsystems to make estimation possible. A cascaded controller approach is followed. The helicopter’s fast angular dynamics are separated from the slower translational dynamics. A linear quadratic regulator is used to control the helicopter’s attitude dynamics. An optimised PID outer-loop generates attitude commands from a given inertial position trajectory. The PID controllers are optimised using a simplex search method. An observer estimates the unmeasured states such as blade flapping. The controller is developed in Simulink®, and a plug-in written for AeroSIMRC enables Simulink® to control the simulator through a UDP interface to validate the model and controller. The identified state space model is able to accurately model the flight data from the simulator. The controllers perform well, keeping the helicopter stable even in the presence of considerable disturbances. The attitude controller’s performance is validated using an aeronautical design standard (ADS-33E-PRF) for handling qualities. The trajectory tracking is validated in a series of simulator flight tests. The linear controller is able to sustain stable flight in constant winds of up to 60% of the helicopter’s maximum airspeed. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

The use of rotary winged unmanned aerial vehicles in military and civilian applications is rapidly increasing. The primary objective of this study is to develop an automatic flight control system for a radio controlled (RC) helicopter. There is a need for a simple, easy to use methodology to develop automatic flight controllers for first-flight. In order to make the work accessible to new research groups without physical helicopter platforms, a simulation environment is created for validation. The size 30 RC helicopter in AeroSIMRC is treated as the final target platform. A grey box, timedomain system identification method is used to estimate a linear state space model that operates around hover. Identifying the unknown parameters in the model is highly dependent on the initial guess values and the input data. The model is divided into subsystems to make estimation possible. A cascaded controller approach is followed. The helicopter’s fast angular dynamics are separated from the slower translational dynamics. A linear quadratic regulator is used to control the helicopter’s attitude dynamics. An optimised PID outer-loop generates attitude commands from a given inertial position trajectory. The PID controllers are optimised using a simplex search method. An observer estimates the unmeasured states such as blade flapping. The controller is developed in Simulink®, and a plug-in written for AeroSIMRC enables Simulink® to control the simulator through a UDP interface to validate the model and controller. The identified state space model is able to accurately model the flight data from the simulator. The controllers perform well, keeping the helicopter stable even in the presence of considerable disturbances. The attitude controller’s performance is validated using an aeronautical design standard (ADS-33E-PRF) for handling qualities. The trajectory tracking is validated in a series of simulator flight tests. The linear controller is able to sustain stable flight in constant winds of up to 60% of the helicopter’s maximum airspeed. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Este trabalho trata da modelagem e controle do radiotelescópio de Itapetinga (Atibaia, SP). Ele compreende não só síntese dos modelos e sintonia dos controladores, mas também identificação de sistemas, validação experimental de modelo e controle, reespecificação de componentes, sugestão de nova arquitetura de automação e controle e direcionamento do desenvolvimento que deve ser feito em futuros trabalhos. A parte inicial desta dissertação trata dos principais conceitos envolvidos e do levantamento de informações preliminares para a compreensão do sistema a ser modelado. A seguir é feita a modelagem matemática dos diversos componentes que formam os sistemas de posicionamento dos eixos de elevação e azimute. São então identificados experimentalmente os coeficientes matemáticos dos modelos e são feitas suas validações experimentais. Os controladores PID são sintonizados, baseados na simulação das malhas de controle através das ferramentas matemáticas MATLAB e Simulink. A validação experimental dos controladores é feita e comparada ao sistema de controle atual. São feitos os encaminhamentos das definições de novos motores e amplificadores e desenvolvida uma nova proposta de arquitetura para controle e supervisão do radiotelescópio, dando a ele funcionalidades muito além das que existem atualmente. Finalmente é dado o direcionamento dos próximos passos de desenvolvimento dos modelos, controladores e arquitetura de controle. Com este trabalho procura-se aumentar significativamente o entendimento do sistema de posicionamento do radiotelescópio, criando novos horizontes para o controle, operação, supervisão e manutenção do mesmo. / This work covers the modeling and control of the radio telescope of Itapetinga (Atibaia, SP). It tackles not only model synthesis and controllers tuning, but also system identification, experimental validation of model and control, re-specification of components, as well as a suggestion of a new automation and control architecture, and suggestions for future works. The initial part of this dissertation covers the main concepts and preliminary information for the understanding of the system to be modeled. Then a math model of the several components that form the pointing systems of the elevation and azimuth axis is done, followed by the experimental identification and validation of the math coefficients for the model. PID controllers are tuned based on the simulation of control loops using the math tools MATLAB and Simulink. Then the experimental validation of the controllers is done and compared to the current system control. Preliminary definitions of new motors and amplifiers are suggested, and a new proposal of architecture for radio telescope\'s control and supervision is developed, expanding its functionalities far beyond the ones available today. Finally, directions for the next steps to be taken in order to develop models, controllers and control architecture are given. This work aims to greatly increase the understanding of the radio telescope\'s pointing system, creating new horizons for its control, operation, supervision and maintenance.