Identification of the harmonic transfer functions of a helicopter rotor
Author(s)Siddiqi, Afreen, 1977-
Harmonic transfer functions of a helicopter rotor
Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.
Steven R. Hall.
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Identification of the time periodic dynamics of a helicopter rotor system is necessary for effective controller design and analysis. The transfer properties of a linear time periodic (LTP) system can be described by harmonic transfer functions (HTF) that give the input-output relationship between the Fourier coefficients of the input signal and those of the output signal. A method for identifying harmonic transfer functions of linear time periodic systems is developed in this thesis. The system identification scheme employs a least square estimation technique to obtain HTF estimates. This least square estimation problem is under-determined; therefore, an additional assumption, that the transfer function is smooth, is made in the ID scheme to achieve a well-posed problem. The estimates are calculated by applying a quadratic penalty to the curvature of the transfer functions. The identification scheme has been implemented in MATLAB, and partly coded in C programming language for maximum computational efficiency. This system ID method has been validated with analytical results for a few well-known LTP systems. The validation results show excellent agreement between the identified and analytical transfer functions.
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.Includes bibliographical references (leaves 68-69).
DepartmentMassachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.
Massachusetts Institute of Technology
Aeronautics and Astronautics.