File:Application of chaos methods to helicopter vibration reduction using Higher Harmonic Control (IA applicationofcha1094530715).pdf
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Summary[edit]
Application of chaos methods to helicopter vibration reduction using Higher Harmonic Control ( ) | ||
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Author |
Sarigul-Klijn, Martinus M. |
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Title |
Application of chaos methods to helicopter vibration reduction using Higher Harmonic Control |
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Publisher |
Monterey, California. Naval Postgraduate School |
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Description |
Chaos is a discipline used in understanding complex nonlinear dynamics. The geometric and topological methods of Chaos theory are applied, for the first time, to the study of flight test data. Data analyzed is from the McDonnell Douglas OH-6A Higher Harmonic Control (HHC) test aircraft. HHC is an active control system used to suppress helicopter vibrations. Some of the first practical applications of Chaos methods are demonstrated with the HHC data. Although helicopter vibrations are mostly periodic, evidence of chaos was found. The presenc3e of a strange attractor was shown by computing a positive Lyapunov exponent and computing a non-integer fractal correlation dimension. Also, a broad band Fourier spectrum and a well defined attractor in pseudo phase space are observed. A limit exists to HHC vibration reduction due to the presence of chaos. A new technique based on a relationship between the Chaos methods (the Poincare section and Van der Pol plane) and the vibration amplitude and phase was discovered. This newly introduced technique results in the following: 1) it gives the limits of HHC vibration reduction, 2) it allows rapid determination of best phase for a HHC controller, 3) it determines the minimum HHC controller requirement for any helicopter from a few minutes duration of flight test data (for the OH-6A, a scheduled gain controller for HHC appears to be adequate for steady level flight), 4) it shows that the HHC controller transfer matrix is linear and repeatable when the vibrations are defined in the "Rotor Time Domain" and that the matrix is nonlinear and nonrepeatable when the vibrations are defined in the "Clock Time Domain." This technique will reduce future HHC flight test requirements. Further, the technique does not require the helicopter to be equipped with HHC. These methods may be applicable to other vibration control and flight testing problems. Subjects: Aerodynamics; Helicopters; Helicopters,Flight testing; Lyapunov functions.; Chaos; Higher Harmonic Control; nonlinear dynamics; strange attractor; fractal dimension; Lyapunov exponent; poincare section; Van der Pol plane; control systems |
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Language | English | |
Publication date |
March 1990 publication_date QS:P577,+1990-03-00T00:00:00Z/10 |
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Current location |
IA Collections: navalpostgraduateschoollibrary; fedlink |
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Accession number |
applicationofcha1094530715 |
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Source | ||
Permission (Reusing this file) |
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, may not be copyrighted. |
Licensing[edit]
Public domainPublic domainfalsefalse |
This file is a work of a sailor or employee of the U.S. Navy, taken or made as part of that person's official duties. As a work of the U.S. federal government, it is in the public domain in the United States.
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This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights. |
https://creativecommons.org/publicdomain/mark/1.0/PDMCreative Commons Public Domain Mark 1.0falsefalse
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current | 09:51, 8 July 2020 | 1,275 × 1,650, 203 pages (5.83 MB) | Fæ (talk | contribs) | FEDLINK - United States Federal Collection applicationofcha1094530715 (User talk:Fæ/IA books#Fork8) (batch 1990-1992 #3201) |
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Short title | Application of chaos methods to helicopter vibration reduction using Higher Harmonic Control |
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Author | Sarigul-Klijn, Martinus M. |
Software used | Sarigul-Klijn, Martinus M. |
Conversion program | |
Encrypted | no |
Page size |
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Version of PDF format | 1.4 |