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An electro-dynamic Magnetic Levitation vehicular system has been modelled and studied. In practice, a MagLev vehicle will consist of a number of cars which are mechanically coupled to each other. It is reasonable to assume that each of these cars will be independently controlled with the help of a supervisory controller. This thesis deals with the control aspects of one such car. The car is equipped with two control magnets one at the front end and the other at the rear end. The currents in these magnets can be varied to provide levitation and pitch-axis control. The rotational aspects of the vehicle about the yaw and roll axes is neglected here. The car has also a horizontal thrust producing mechanism, the dynamics of which has been neglected. A controller has been devised using frequency domain analysis. It is shown that the vehicle Can be controlled effectively to meet nominal ride specifications. These specifications are derived both from the point of practical implementation of the vehicle and from the need to ensure good ride quality. The controller needs to be robust in its operation. This thesis shows that a simple controller configuration is enough to maintain satisfactory operation for a variety of operating conditions. It is also shown that in the event of a disrupted magnet circuit, normal operation can be restored with a backup set, without having to stop the vehicle or endanger its occupants. This study is entirely conceptual and no attempt has been made to practically implement the system. It should also be noted that a reasonable choice was made for the parameters of the model, that compares closely to data from existing MagLev systems. / Graduation date: 1991

The research described in this dissertation deals with an open problem concerning the synthesis of controllers of xed order and structure. This problem is encountered in a variety of applications. Simply put, the problem may be put as the determination of the set, S of controller parameter vectors, K = (k1; k2; : : : ; kl), that render Hurwitz a family (indexed by F) of complex polynomials of the form fP0(s; ) + Pl i=1 Pi(s; )ki; 2 Fg, where the polynomials Pj(s; ); j = 0; : : : ; l are given data. They are specied by the plant to be controlled, the structure of the controller desired and the performance that the controllers are expected to achieve. Simple examples indicate that the set S can be non-convex and even be disconnected. While the determination of the non-emptiness of S is decidable and amenable to methods such as the quantier elimination scheme, such methods have not been computationally tractable and more importantly, do not provide a reasonable approximation for the set of controllers. Practical applications require the construction of a set of controllers that will enable a control engineer to check the satisfaction of performance criteria that may not be mathematically well characterized. The transient performance criteria often fall into this category. From the practical viewpoint of the construction of approximations for S, this dissertation is dierent from earlier work in the literature on this problem. A novel feature of the proposed algorithm is the exploitation of the interlacing property of Hurwitz polynomials to provide arbitrarily tight outer and inner approximation to S. The approximation is given in terms of the union of polyhedral sets which are constructed systematically using the Hermite-Biehler theorem and the generalizations of the Descartes' rule of signs.

The research described in this dissertation deals with an open problem concerning the synthesis of controllers of xed order and structure. This problem is encountered in a variety of applications. Simply put, the problem may be put as the determination of the set, S of controller parameter vectors, K = (k1; k2,...,kl), that render Hurwitz a family (indexed by F) of complex polynomials of the form {P0(s.a) + [summation] i=1 Pi(s,a)ki, a [set membership] F}, where the polynomials Pj(s,a), j = 0,...,l are given data. They are specied by the plant to be controlled, the structure of the controller desired and the performance that the controllers are expected to achieve. Simple examples indicate that the set S can be non-convex and even be disconnected. While the determination of the non-emptiness of S is decidable and amenable to methods such as the quantier elimination scheme, such methods have not been computationally tractable and more importantly, do not provide a reasonable approximation for the set of controllers. Practical applications require the construction of a set of controllers that will enable a control engineer to check the satisfaction of performance criteria that may not be mathematically well characterized. The transient performance criteria often fall into this category. From the practical viewpoint of the construction of approximations for S, this dissertation is dierent from earlier work in the literature on this problem. A novel feature of the proposed algorithm is the exploitation of the interlacing property of Hurwitz polynomials to provide arbitrarily tight outer and inner approximation to S. The approximation is given in terms of the union of polyhedral sets which are constructed systematically using the Hermite-Biehler theorem and the generalizations of the Descartes' rule of signs.

Thesis (MTech (Electrical Engineering))--Peninsula Technikon, 2002. / Word processed copy. Summary in English. Includes bibliographical references (p. 115-119). Also available online.

published_or_final_version / Statistics / Master / Master of Social Sciences

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

Bibliography: leaves 329-348 / xxi, 348 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1987

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 90-92). Also available on the World Wide Web.