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Title: Eigenstructure assignment for helicopter flight control
Author: Pomfret, Andrew James
ISNI:       0000 0001 3494 1544
Awarding Body: University of York
Current Institution: University of York
Date of Award: 2006
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Traditional approaches to helicopter control law design involve the iterative application of single-input, single-output loop-at-a-time classical methods. Helicopters are typically highly cross-coupled systems, and such approaches become very laborious under these conditions. Modern multi variable techniques, despite their ability to solve control design problems very efficiently, have not been embraced by practitioners. One possible reason for this is the lack of design visibility provided by such techniques, in terms of performance and controller structure. This thesis presents new observations and algorithms which address this problem. Eigenstructure assignment is introduced in the context of classical control in order to illustrate the extent to which the two methodologies share a common language of expression. The sources of the primary dynamics of a helicopter are identified, and a new ideal eigenstructure is derived which fulfills the UK Def.Stan.00-970 handling qualities specification. Dynamic compensators are investigated in detail, to identify the distribution of the design freedom added by these structures and its possible uses in the context of eigenstructure assignment. It is found that the manner in which the freedom is expressed does not lend itself to eigenstructure assignrrient, and so other sources of design freedom are sought. This leads to the development of two novel algorithms, and several extensions, for the assignment of eigenstructure to systems with a direct transmission term and consequently to helicopters with acceleration feedback or proportional-plus-derivative control structures. The use of design freedom remaining after eigenstructure assignment is considered, and an algorithm for using it to impose structure on the controller without affecting the assigned eigenstructure is developed. Finally all of the algorithms developed in the thesis, along with the ideal eigenstructure, are demonstrated by application to a linearised helicopter model.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available