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TECHNICAL PAPERS

Adaptive Method of Helicopter Track and Balance

[+] Author and Article Information
Shengda Wang

Department of Mechanical and Industrial Engineering,  University of Massachusetts, Amherst, MA 01003-2210

Kourosh Danai1

Department of Mechanical and Industrial Engineering,  University of Massachusetts, Amherst, MA 01003-2210danai@ecs.umass.edu

Mark Wilson

 Sikorsky Aircraft, Stratford, CT

An explored input represents an input for which the exact value of the output is available. In track and balance, an explored input would denote a blade adjustment that has been applied to the helicopter.

1

Corresponding author.

J. Dyn. Sys., Meas., Control 127(2), 275-282 (May 02, 2004) (8 pages) doi:10.1115/1.1913683 History: Received March 26, 2003; Revised May 02, 2004

An adaptive method of helicopter track and balance is introduced to improve the search for the required blade adjustments. In this method, an interval model is used to represent the range of effect of blade adjustments on helicopter vibration, instead of exact values, to cope with the nonlinear and stochastic nature of aircraft vibration. The coefficients of the model are initially defined according to sensitivity coefficients between the blade adjustments and helicopter vibration, to include the ‘a priori’ knowledge of the process. The model coefficients are subsequently transformed into intervals and updated after each tuning iteration to improve the model’s estimation accuracy. The search for the required blade adjustments is performed according to this model by considering the vibration estimates of all of the flight regimes to provide a comprehensive solution for track and balance. The effectiveness of the proposed method is evaluated in simulation using a series of neural networks trained with actual vibration data. The results indicate that the proposed method improves performance according to several criteria representing various aspects of track and balance.

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Copyright © 2005 by American Society of Mechanical Engineers
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Figures

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Figure 1

Illustration of the position of accelerometers A and B on the aircraft, and the rotor blade adjustments (pitch control rod, trim tab, and hub weights)

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Figure 2

Tuning strategy of the current methods

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Figure 3

The strategy of the proposed tuning method

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Figure 4

Estimated range of output by the interval model using one reference input

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Figure 5

Estimated range of output by the interval model using seven reference inputs

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Figure 6

Typical adaptation of the coefficient intervals to the noise-contaminated outputs of a liner model

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Figure 7

Variation of the feasible region due to learning

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Figure 8

A sample set of simulated vibration changes shown side by side with the actual vibration changes

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