{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/8900"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/8900","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Identification of the harmonic transfer functions of a helicopter rotor","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_html":"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_has_math":false,"creators":["Siddiqi, Afreen, 1977-"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.","school":null,"contributors":[],"advisors":["Steven R. Hall."],"committee_chairs":[],"committee_members":[],"year":2001,"date_issued":"2001","date_published":"2001","updated_at":"2026-07-22T22:21:09Z","subjects":["Aeronautics and Astronautics."],"languages":["eng"],"rights":["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."],"rights_urls":["http://dspace.mit.edu/handle/1721.1/7582"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1721.1/8900","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Steven R. Hall."]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics."]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Massachusetts Institute of Technology. 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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."]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://dspace.mit.edu/handle/1721.1/7582"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1721.1/8900"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.","Includes bibliographical references (leaves 68-69)."]},{"key":"dc:description.abstract","label":"Abstract","values":["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."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["S.M."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Identification of the harmonic transfer functions of a helicopter rotor"]}]}],"canonical_facts":{"dc:contributor.advisor":["Steven R. Hall."],"dc:contributor.department":["Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics."],"dc:contributor.other":["Massachusetts Institute of Technology. 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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."],"dc:description.degree":["S.M."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/1721.1/8900"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["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."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Aeronautics and Astronautics."],"dc:title":["Identification of the harmonic transfer functions of a helicopter rotor"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:21:09Z"}