Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
A robust strategy to stabilize aircraft landing gear shimmy under structural uncertainties
Submission Author:
Luis Eduardo Prado Pereira , Buscando endereço... , Brazil
Co-Authors:
Luis Eduardo Prado Pereira, José Augusto Ignacio da Silva, Flavio D. Marques
Presenter: Luis Eduardo Prado Pereira
doi://10.26678/ABCM.COBEM2021.COB2021-0297
Abstract
Shimmy in aircraft landing gears is a nonlinear dynamic instability commonly caused by structural and tyre-to-ground interaction. The instability onset conditions can be predicted with linearized models that depend primarily on the structural dynamics and simplified linear tyre loads. The shimmy self-excited mechanism is driven by divergent unstable motion that can define the phenomenon's boundaries in terms of vertical force and forward speed, limiting the aircraft's operational landing envelope. The control of the shimmy instability has been performed with passive and active techniques. Although there are different control design strategies, the shimmy dynamics' stabilization is still a formidable challenge. In this context, this work proposes an approach to suppress unstable shimmy motion, considering uncertainties on a landing gear structure. The landing gear model comprises torsional landing gear dynamics and tyre loads based on nonlinear coupled lateral displacement and self-alignment angular motion. Polytopic convex hulls are used to describe the uncertainties, and Lyapunov's stability function with Linear Matrix Inequalities (LMIs) are used to design a robust controller. Numerical simulations are carried out to demonstrate that the control gain can asymptotically stabilize the system responses to assure a safe shimmy-free landing envelope. A complete analysis of the control performance is also presented.
Keywords
Shimmy, Aircraft landing gears, Structural uncertainties, Robust controller, LMIs
