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Analysis and Design of Adaptive Control Systems Based on Contraction Theory

Boveiri, Mohammmad | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54680 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Tavazoei, Mohammad Saleh
  7. Abstract:
  8. 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 controller is more general than the existing adaptive output feedback ones because it does not assume any constraint on the structure of the system and the parametric uncertainty. Section III develops an adaptive actuator failure compensation method for uncertain nonlinear systems. The proposed method, 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 compensation methods, as it does not require the system to have an identical relative degree for all inputs and be transformable into the parametric strict-feedback or feedback linearization form
  9. Keywords:
  10. Nonlinear Control ; Adaptive Control ; Riemannian Geometry ; Contraction Analysis ; Output Feedback ; Actuator Failure

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