Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Not available / text

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 144-148). Also available via the Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 259-271). Also available via the Internet.

Thesis (M.S.)--Ohio University, March, 1990. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, November, 1991. / Title from PDF t.p.

No description available.

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Apr. 2, 2010). Includes bibliographical references (p. 135-139).

This study examines the characteristics of four methods for the control of flexible structures and investigates the control performances of each method. The investigation is concerned with various control performance measures, such as control gain magnitude, settling time and overshoot in transient response, actuator phase and gain margins, and stability in the presence of actuator failure. In conjunction with the system performance, a systematic approach to the choice of weighting matrices for optimal control is presented. The approach shows a relation between the weighting matrices and the closed-loop eigenvalues. Since the approach is based on a set of independent second·order modal dynamics, the dimensionality of the system is no longer a problem in obtaining the optimal control law. The newly developed Minimum Gain Pole Placement (MGPP) is an optimal method in the sense that it minimizes an objective function, where the objective function is taken as control gain magnitudes with constraints of exact pole placement for any set of modes. The robustness of Independent Modal Space Control (IMSC) is examined. In general, the parameters of the control system are usually approximated, so that the designed controller, based on a postulated model, will not perform on the actual system as expected. This study shows that when the IMSC method is used with collocated sensors and actuators, the modelling errors in the postulated system cannot lead to instability of the closed-loop system containing control modes and residual modes.However, in the case of coupled control (MGPP), this property cannot be shown. This points to the robustness of IMSC method with respect to modelling errors. The IMSC method requires the same number of actuators as the number of control modes. The method can be extended to the cases of fewer actuator and more actuator by using the pseudo-inverse of modal particification matrix, an approach referred to as pseudo-independent modal-space control (PIMC). It is shown that PIMSC also yields some form of optimal control and that it is robust as well. Modal filters are introduced to detect and identify failure of control components in large space structures. The failure mode is investigated in the modal space so that a simple failure detection and identification (FDI) based on modal dynamics is established. Moreover the information obtained from the modal analysis provides some guidelines for the identification of faulty components. The integral form of the modal filters provides the ability to mitigate the effects of noise, disturbances and parameter uncertainties pointing to the robustness of the method. The detection process proposed in this study reduces the computational effort and permits an assessment of the system stability. / Ph. D. / incomplete_metadata

This thesis examines several techniques for the design of decentralized control strategies for the active control of vibrational damping in large space structures. A brief description of the finite element method is presented to explain the derivation of mathematical models of flexible structures represented by systems of linear second-order ordinary differential equations. The fundamental ideas of modal analysis are introduced to explain the concepts of vibrational modes and mode shapes, and derive the modal coordinate state space representation of flexible structures. The decentralized fixed modes of a system are defined, and several important characterizations of decentralized fixed modes are presented. Alternate characterizations of fixed modes yield additional insight into the nature: of fixed modes and often provide new methods for calculating the fixed modes of a system. The use of collocated rate feedback for robust vibrational damping control is described. It is shown that the robustness of collocated rate feedback is due to the positivity of large space structures, an extension of the mathematical concept of positive real functions to dynamic systems. Another strategy for the control of vibrational damping in large space structures, known as uniform damping control, is also described. It is shown that compared to collocated rate feedback, uniform damping control achieves increased performance at the price of decreased robustness at low frequencies. The application of decomposition techniques to the design of decentralized control laws is described, and a special type of decomposition known as an overlapping decomposition is introduced. It is shown how overlapping decompositions can be used to design control laws for systems for which the more familiar disjoint decomposition techniques often fail to yield satisfactory results. Finally, these decentralized control techniques are illustrated using a model of a proposed large space structure, the NASA CO FS mast. / Master of Science