Publications by authors named "Sean Shan-Min Swei"

2 Publications

  • Page 1 of 1

LPV Modeling of a Flexible Wing Aircraft Using Modal Alignment and Adaptive Gridding Methods.

Aerosp Sci Technol 2017 Jul 10;66:92-102. Epub 2017 Mar 10.

Intelligent Systems Division, NASA Ames Research Center.

One of the earliest approaches in gain-scheduling control is the based approach, in which a set of local linear time-invariant models are obtained at various gridded points corresponding to the varying parameters within the flight envelop. In order to ensure smooth and effective Linear Parameter-Varying control, aligning all the flexible modes within each local model and maintaining small number of representative local models over the gridded parameter space are crucial. In addition, since the flexible structural models tend to have large dimensions, a tractable model reduction process is necessary. In this paper, the notion of -shifted [Formula: see text]- and [Formula: see text]-norm are introduced and used as a metric to measure the model mismatch. A new modal alignment algorithm is developed which utilizes the defined metric for aligning all the local models over the entire gridded parameter space. Furthermore, an Adaptive Grid Step Size Determination algorithm is developed to minimize the number of local models required to represent the gridded parameter space. For model reduction, we propose to utilize the concept of Composite Modal Cost Analysis, through which the collective contribution of each flexible mode is computed and ranked. Therefore, a reduced-order model is constructed by retaining only those modes with significant contribution. The NASA Generic Transport Model operating at various flight speeds is studied for verification purpose, and the analysis and simulation results demonstrate the effectiveness of the proposed modeling approach.
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http://dx.doi.org/10.1016/j.ast.2017.03.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5713486PMC
July 2017

Optimum Wing Shape Determination of Highly Flexible Morphing Aircraft for Improved Flight Performance.

J Aircr 2016 09 10;53(5):1305-1316. Epub 2016 Mar 10.

Michigan State University, East Lansing, MI 48824.

In this paper, optimum wing bending and torsion deformations are explored for a mission adaptive, highly flexible morphing aircraft. The complete highly flexible aircraft is modeled using a strain-based geometrically nonlinear beam formulation, coupled with unsteady aerodynamics and 6-dof rigid-body motions. Since there are no conventional discrete control surfaces for trimming the flexible aircraft, the design space for searching the optimum wing geometries is enlarged. To achieve high performance flight, the wing geometry is best tailored according to the specific flight mission needs. In this study, the steady level flight and the coordinated turn flight are considered, and the optimum wing deformations with the minimum drag at these flight conditions are searched by utilizing a modal-based optimization procedure, subject to the trim and other constraints. The numerical study verifies the feasibility of the modal-based optimization approach, and shows the resulting optimum wing configuration and its sensitivity under different flight profiles.
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http://dx.doi.org/10.2514/1.C033490DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5770154PMC
September 2016
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