| | | Document Type | : | Latin Dissertation | | Language of Document | : | English | | Record Number | : | 54022 | | Doc. No | : | TL23976 | | Call number | : | DP19480 | | Main Entry | : | Mohammad Rastgaar-Aagaah | | Title & Author | : | Vibration Suppression using Orthogonal Eigenstructure ControlMohammad Rastgaar-Aagaah | | College | : | Virginia Polytechnic Institute and State University | | Date | : | 2008 | | Degree | : | Ph.D. | | student score | : | 2008 | | Page No | : | 233 | | Abstract | : | A novel control method called orthogonal eigenstructure control is developed for active vibration cancellation in structures. Orthogonal eigenstructure control is a feedback control method applicable to multi-input multi-output linear systems. While the available control design methodologies offer a large and complex design space of options that can often overwhelm a designer, this control method offers a significant simplification of the design task while still allowing some experience-based design freedom. For example, eigenstructure assignment methods need definition of a desired eigenvector for the closed-loop system. The controller designer may also be required to do pole placement. Considering the fact that there are no one-to-one relationships between the elements of the closed-loop eigenvectors of a model and the states of the system, this effort could be inefficient for many practical systems. Moreover, for large-scale systems, defining or shaping the eigenstructures become a relatively difficult task. Orthogonal eigenstructure control is a state feedback-like control law that is relatively easy to design and implement to multiple-input multiple-output systems. It allows control engineers to achieve good performing designs even with little design experience, while the existing methods are highly dependent on designer experience. The control method developed in this study, uses the fact that each open-loop eigenvector lies within the achievable closed-loop eigenvector set, since it is associated with the zero output feedback control gain matrix. By defining the achievable eigenvector set for each open-loop eigenvalue, a class of the vectors orthogonal to the open-loop eigenvectors can be considered to be substituted as the associated eigenvector, eliminating the need for any guesswork by the controller designer. The proposed concept eliminates the error due to differences between the achievable and desirable eigenvectors, since the open-loop eigenvectors are replaced by the vectors orthogonal to them that are already within the achievable eigenvector set. When the open-loop model of the system is available, some of the target eigenvalues can be determined and their respective eigenvectors are orthogonalized. If the first orthogonal vector does not lead to a satisfactory performance, the method uses another orthogonal vector to be substituted. It has been shown that the dynamic modes of a system with eigenvectors that are orthogonal to each other are decoupled and there is less spillover of energy from one mode to another, leading to a system with better performance. Orthogonal eigenstructure control is introduced and extended to be applicable to linear systems regardless of the number and location of the actuators and sensors. Also, the concept of progressive application of the proposed control method for increasing robustness is described. Finally, the result of application of the control method for vibration cancellation of a test plate is investigated through experiments for tonal and wideband disturbances. The results show a significant reduction of vibrations using the orthogonal eigenstructure control with relative ease in finding the control gain matrix. | | Subject | : | Applied sciences; Active vibration cancellation; Orthogonal eigenstructure control; Mechanical engineering; 0548:Mechanical engineering | | Added Entry | : | M. S. Ahmandian, Steve C. | | Added Entry | : | Virginia Polytechnic Institute and State University |
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