Flutter Control with Unsteady Aerodynamic Models.
Abstract
This dissertation deals with a generic problem for aircraft: control laws for flutter suppression. Until recently, the system frequency response was approximated by rational functions so that the finite-dimensional L-Q-R theory could be applied. However, discrepancies between theory and practice, especially in transient response, has led to renewed interest in the problem. It would appear the L-Q0R theory would need infinite dimensional state space models. In this research, we first develop a time-domain model for unsteady aerodynamic loads and then couple it with a lumped model for the structural dynamics. We show that the solutions to the resulting input-output system, characterized by integro-differential equations, can be endowed with a state space which is a reflexive Banach space, and the state equations have a unique semigroup solution. We go on to examine the input-output stability for such a system. We show that input-output stability need not imply stability of the states. By a suitable approximation of the Sears function near the origin, we show that infinite dimensional (L2) L-Q-R theory can be applied. We derive optimal feedback control laws ensuring 'weak' stability of the states, as well as input-output stability.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1984
- Accession Number
- ADA147858
Entities
People
- Shi Chang
Organizations
- University of California, Los Angeles