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

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2018

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Gürler, Mustafa

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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.

Subject Keywords

Helicopters, Chebyshev polynomials., Helicopters, Fourier series.

URI

http://etd.lib.metu.edu.tr/upload/12622866/index.pdf
https://hdl.handle.net/11511/27872

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

M. Gürler, “Mathematical modeling of a small-scale helicopter and mrac design with time based uncertainty parametrizations,” M.S. - Master of Science, Middle East Technical University, 2018.