Incorporation of Feedback Control into a High-Fidelity Aeroservoelastic Fighter Aircraft Model

Abstract

Flight testing for aeroservoelastic clearance is an expensive and time consuming process. Large degree-of-freedom high-fidelity nonlinear aircraft models using computational fluid dynamics coupled with finite element models can be used for accurately predicting aeroelastic phenomena in all flight regimes including subsonic, supersonic, and transonic. With the incorporation of an active feedback control system, these high-fidelity models can be used to reduce the flight-test time needed for aeroservoelastic clearance. Accurate computational fluid dynamics/finite element models are computationally complex, rendering their runtime ill suited for adequate flight control system design. In this work, a complex, large-degree-of-freedom, transonic, inviscid computational fluid dynamics/finite element model of a fighter aircraft is fitted with a flight control system for aeroelastic oscillation reduction. A linear reduced-order model of the complete aeroelastic aircraft dynamic system is produced directly from the high-order nonlinear computational fluid dynamics/finite element model. This rapid runtime reduced-order model is used for the design of the flight control system, which includes models of the actuators and common nonlinearities in the form of rate limiting and saturation. The oscillation reduction controller is successfully demonstrated via a simulated flight test using the high-fidelity nonlinear computational fluid dynamics/finite element/flight control system model.

A method for normal-mode-based model reduction in nonlinear dynamics of slender structures

“…Consequently, the resulting computational cost is increased manifold [2,3] and may become prohibitive for routine design analysis. An additional requirement is posed by the initial (model-based) design of the flight control and gust/manoeuvre load alleviation systems, which call for the ability to generate small-size descriptions of the system dynamics using methods of model reduction [4].…”

Saturated RISE Tracking Control of Store-Induced Limit Cycle Oscillations

“…Several control strategies have been developed to mitigate LCO behavior in an aeroelastic system requiring exact knowledge of the dynamics including linear-quadratic regulator (LQR), 3,17,23 feedback linearization, 12 linear multivariable control on a linear reduced order model, 6,21 and State-Dependent Riccati Equation and sliding mode control approaches. 8 These controllers do not compensate for uncertainties in the aerodynamic and structural models or external disturbances and are restricted to specific flight regimes.…”

Attitude Stabilization for Lunar and Planetary Lander with Variable Damper

“…Several control strategies have been developed to mitigate LCO behavior in an aeroelastic system requiring exact knowledge of the dynamics, including linear-quadratic regulator (LQR) [3][4][5], feedback linearization [6], linear multivariable control on a linear reducedorder model [7,8], and state-dependent Riccati equation and sliding-mode control approaches [9]. These controllers do not compensate for uncertainties in the aerodynamic and structural models or external disturbances and are restricted to specific flight regimes.…”