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boveiri--mohammmad
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Dynamic Behavior and Stability Analysis of Rotor-Seal System
, M.Sc. Thesis Sharif University of Technology ; Mohammmad Navazi, Hossein (Supervisor)
Abstract
The present research aims to achieve two main objectives in the Rotordynamic. The first one is, study and calculate the linear dynamic coefficients of a tapered gas seal, and the second one is, analysis the dynamic behavior and stability of the Timoshenko rotor supported with tapered gas seal. Classical Reynolds equation is used to calculate the dynamic coefficients of tapered gas seal. At first, using the perturbation method, the perturbed equations for gas film thickness and pressure are obtained. The finite difference method (FDM) is utilized to transfer the obtained PDEs to the algebraic system of equations. The algebraic system of equations then solved, and the zeroth and first-order...
Adaptive actuator failure compensation on the basis of contraction metrics
, Article IEEE Control Systems Letters ; Volume 6 , 2022 , Pages 1376-1381 ; 24751456 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This letter develops an adaptive actuator failure compensation method for nonlinear systems with unmatched parametric uncertainty based on contraction metrics. The proposed method, which is constructed by benefiting from the recent achievements on contraction metrics based adaptive control techniques, ensures the closed-loop stability and asymptotic tracking of the desired trajectory in the presence of actuator failures. In particular, a sufficient convex condition is derived for constructing a valid metric, by which a quadratic program-based controller is obtained to determine the inputs of the actuators. The introduced method is more general than the common adaptive actuator failure...
Analysis and Design of Adaptive Control Systems Based on Contraction Theory
, M.Sc. Thesis Sharif University of Technology ; Tavazoei, Mohammad Saleh (Supervisor)
Abstract
This thesis deals with output feedback control design, adaptive output feedback control design, and adaptive actuator compensation for input-affine nonlinear systems on the basis of contraction metrics. In Section I, some necessary backgrounds on Riemannian geometry and contraction analysis are presented. In Section II, firstly, an observer for the considered class of nonlinear systems is proposed. Then, it is shown that by combining the introduced observer with state-feedback controllers in a suitable way, output tracking can be achieved. Moreover, the obtained results are extended to be used for adaptive output feedback stabilization of uncertain nonlinear systems. The introduced...