Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Periodic Disturbance Estimation Based Robust Control of Marine Vehicles(Izmir Institute of Technology, 2020) Kurtoğlu, Deniz; Tatlıcıoğlu, EnverHighly uncertain and complex structures of marine vehicles render the control problem a challenging task. Moreover, the problem becomes much more challenging when the system is exposed to environmental disturbances. This thesis tackles this control problem with an adaptive robust control algorithm which is fused with a periodic disturbance estimation method. The periodic disturbance estimation method inspired from a Fourier series expansion technique is applied for compensation of environmental forces. In the first part of the thesis, an adaptive full state feedback backstepping controller which is supported with the periodic disturbance estimation method is applied. Stability of the closed–loop system and the convergence of the tracking error are established via Lyapunov based methods. Simulation studies are provided to support the theoretical results and to demonstrate the effectiveness of the proposed method. In the second part of the thesis, a nonlinear model free observer based adaptive output feedback controller in conjunction with the periodic disturbance estimator is designed. Lyapunov based arguments have been utilized to prove the stability of the closed– loop system, and the convergence of the tracking and observer errors under the closed– loop operation. Performance and viability of the proposed method are demonstrated via numerical simulations.Master Thesis Modelling and Control of Hypersonic Aircraft Vehicles(Izmir Institute of Technology, 2012) Bıdıklı, Barış; Tatlıcıoğlu, EnverThe increasing number of works on hypersonics and the recent interest of Ministry of Defense on developing a hypersonic missile are amongst the main motivations behind this thesis. Research on hypersonics seems to divide into two main categories: deriving dynamic models for HSVs and designing model-based controllers. Initially, we decided to investigate the control problems associated with HSVs. However, due to the restrictions imposed by the leading sponsors of hypersonic research (such as NASA, US AF, US DoD, DARPA, etc), researchers did neither publish nor share the model parameters for HSVs. As a result, our initial focus was deriving a dynamic model for an HSV. Firstly, modelling approaches for HSVs and we noticed that it is extremely hard to directly obtain the HSV dynamic model parameters. In addition to this, the HSV nonlinear dynamic model which was commonly mentioned in the literature is not related to the control inputs directly. As a result, the linearized HSV dynamic models were investigated, and the linear parameter varying model was derived. Next, control problems associated with the HSVs are investigated. Due to the highly complicated and time-varying nature of their dynamics, designing a robust control law is aimed. The main reason behind choosing to design a robust control law was that the robust controllers usually require minimum knowledge about the HSV dynamics. The stability of the proposed robust control law is then investigated via Lyapunov-based techniques and the tracking error is driven to the origin exponentially fast by using designed controller.