Development and Validation of Nonlinear Models for Helicopter Dynamics

Gray, Gary James (1992) Development and Validation of Nonlinear Models for Helicopter Dynamics. PhD thesis, University of Glasgow.

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Abstract

The need for validated nonlinear helicopter models and methods to validate these models directly is identified. Published validation methods for validating nonlinear dynamic models are reviewed and the need for an integrated approach is established. Sensitivity coefficient based validation techniques are investigated. Single value sensitivity coefficients are found to be useful for parameter and output variable selection. Examination of sensitivity coefficients time histories is found to be a useful addition to parametric validation methods. A model distortion technique is evaluated. The method is tested with simple systems and simulated data as well as a helicopter model and real ffight data. The method is discussed. Its application to helicopter dynamics is rejected because of noise problems. A nonlinear one degree of freedom yaw model for an Aerospatiale SA.330 PUMA helicopter is improved and validated using analogue matching and a parameter estimation method which uses a linear search. The importance of physical knowledge of the system being modelled is highlighted in the development of the model. A nonlinear mathematical model of a helicopter main rotor is validated in two specific areas. These are the lag damper and the engine/rotor speed model. The validation techniques used are maximum likelihood parameter estimation with sensitivity coefficient examination and analogue matching of time response data. The importance of good physical knowledge of the system being modelled is again indicated. The structure of the model in the identified areas is validated. The validation methods are brought together in a specification for an interactive inodel validation computer package. The benefits of an integrated approach are identified and the computer program is specified so as to take advantage of this. Through this package, the user will interact with the model, the available validation methods and the experimental data and will be able to develop and validate dynamic models easily and efficiently.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: David J Murray
Keywords: Electrical engineering, Aerospace engineering
Date of Award: 1992
Depositing User: Enlighten Team
Unique ID: glathesis:1992-75254
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 21:26
Last Modified: 19 Nov 2019 21:26
URI: http://theses.gla.ac.uk/id/eprint/75254

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