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Steven R. Hall. Siddiqi, Afreen, 1977- Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. Massachusetts Institute of Technology. Department of Aeronautics and Astronautics 2005-08-23T16:13:36Z 2005-08-23T16:13:36Z 2001 2001 http://hdl.handle.net/1721.1/8900 48881143 Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001. Includes bibliographical references (leaves 68-69). 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. by Afreen Siddiqi. S.M. 87 leaves 4776821 bytes 4776581 bytes application/pdf application/pdf eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Aeronautics and Astronautics. Identification of the harmonic transfer functions of a helicopter rotor Harmonic transfer functions of a helicopter rotor Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="38b101ca-faed-4414-943e-a10f57c89baf"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Identification of the harmonic transfer functions of a helicopter rotor</Title> <Subtitle>Harmonic transfer functions of a helicopter rotor</Subtitle> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2001</PublicationDate> <Authors> <Author> <DisplayName>Siddiqi, Afreen, 1977-</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Aeronautics and Astronautics.</Keyword> <Abstract>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.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>