ANALYTICAL RELATIONSHIPS FOR LINEAR-QUADRATIC AEROELASTIC FLIGHT CONTROL EIGENVALUES

Authors
Citation
B. Newman et A. Kassem, ANALYTICAL RELATIONSHIPS FOR LINEAR-QUADRATIC AEROELASTIC FLIGHT CONTROL EIGENVALUES, Journal of guidance, control, and dynamics, 20(6), 1997, pp. 1149-1156
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Instument & Instrumentation","Aerospace Engineering & Tecnology
ISSN journal
0731-5090
Volume
20
Issue
6
Year of publication
1997
Pages
1149 - 1156
Database
ISI
SICI code
0731-5090(1997)20:6<1149:ARFLAF>2.0.ZU;2-D
Abstract
Several obstacles limiting the use of contemporary control design tech niques in production vehicles are noted. These obstacles restrict one from obtaining insight into the control law augmentation of the vehicl e. For example, with the linear quadratic (LQ) state feedback method, detail effects from cost function weight adjustment are not easily und erstood. Further, the role of each feedback loop is not readily appare nt. Fundamental to overcoming this problem is factoring of the LQ char acteristic polynomial. Useful analytical expressions, and ultimately t he relationships they represent, are sought between basic design param eters of the system and the closed-loop eigenvalues, An approximate an alytical factoring technique, previously developed for open-loop appli cations, is considered as a tool for this closed-loop problem. The fir st two terms of a Taylor series are used to capture the polynomial coe fficient dependencies on the polynomial factors. By analytically inver ting the first-order sensitivity matrix, corrections to preliminary ap proximate factors are generated. Expressions for the closed-loop facto rs are in terms of basic parameters such as stability and control deri vatives, structural vibration damping ratio and natural frequency, and cost function weights, allowing key relationships to be uncovered bet ween the design knobs and important closed-loop features.