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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design of a Robust Controller for the Smart Flexible Linkage Using Genetic Algorithms

Chen, Jhih-jyun 27 June 2005 (has links)
The purpose of this thesis is to study the active robust control for the flexible slider-crank linkage mechanism with piezoelectric films using genetic algorithms. The instability caused by the inertia force that is induced by the high-speed rotation flexible slider-crank linkage, mode truncation, parameter uncertainties, and spillover effect due to the residual modes of structure. For the application of the mechanical structure system, a mathematical model for a slider-crank linkage mechanism with piezoelectric films is developed in conjunction with finite element method (FEM), and the lower frequency modes are separated into controlled modes and residual modes. For the robustness of the system, a robust stability condition and genetic algorithms are employed to ensure the stability of the system under the parameter uncertainties and spillover effect simultaneously. Numerical simulation is performed to the control methodology with genetic algorithms can suppress deform of flexible slider-crank linkage mechanism operating at high speeds, and the instability caused by the parameter uncertainties and spillover effect can be avoided.
2

Design of Robust Controllers for Flexible Linkage Mechanism

Liao, Wen-Hwei 18 January 2001 (has links)
The purpose of this dissertation is to study the robust control for the smart flexible linkage mechanism. The control of flexible linkage induced inertia force under high-speed rotation is taken into consideration with the system parameter uncertainties such as modeling error, truncation error, and both of control spillover and observation spillover due to the residual modes of structural control problem. Based on the principles of LQ, optimal model following (OMF) and frequency shaping, this study proposes some sufficient conditions of stability criteria for the design of robust controller, respectively. These techniques guarantee that the controlled plant, under both bounded parameter perturbations and model truncation, could remain stable. Meanwhile, searching for the optimal locating positions of sensor and actuator by applying Taguchi method and genetic algorithm (GA) combined technique is further studied. The system is modeled through employing finite element method (FEM), and the limited lower frequency part modes are separated into controlled modes and residual modes. In time domain, at first we design a Luenberger-observer-based robust controller for the finite-dimensional mode plant keeping stability in a specified region. And then, a robust controller with the OMF is designed for the controlled system to achieve the performance as those of the specified optimum model. From the view of frequency domain, the robust controller could also be deigned according to the frequency shaping principle to suppress the exciting effect of higher frequency residual modes, and similarly avoid that the system might be destabilized. Finally, the combination of Taguchi method and GA technique to search the optimal locations for placing actuator and sensor to coincide with the stability and performance requirement is also done. From the computer simulation, the middle point movement of the linkage is obviously well controlled; hence, the designed robust controllers can certainly suppress the affection of parameter uncertainties and the spillover stimulation of residual modes, and can produce satisfactory results.

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