Mathematical modeling of a small-scale helicopter and MRAC design with time based uncertainty parametrizations

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Havacılık ve Uzay Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2018

Öğrenci: MUSTAFA GÜRLER

Danışman: ALİ TÜRKER KUTAY

Özet:

In this thesis, nonlinear mathematical modeling of a small scale model helicopter is presented. In addition, problems in uncertainty parametrization component of Model Reference Adaptive Control (MRAC) is investigated and external uncertainty on the system is parametrized using universal approximators such as Fourier Series and Chebyshev Polynomials in time dependent form. Advantages of using times based universal approximators in MRAC design of MIMO systems are presented. Proposed controller is tested on the model helicopter using derived mathematical model. Considering special capabilities of the model helicopters, hovering is the most problematic case in terms of stability issues and pilot workload. Therefore, simulations and case studies are performed at hover condition. Moreover, procedure of the MRAC design for a multi input multi output (MIMO) system is given and controller performance is evaluated with and without external disturbance. Adaptive law design and uncertainty parametrization method are the key parts of MRAC design. While the use of e-modification and projection operator in adaptive law improves the controller performance and provide adaptive weights boundedness, proper uncertainty parametrization method selection is important for estimating true adaptive weights.