Control of Limit Cycle Oscillation Amplitudes in Nonlinear Aerelastic Systems using Nonlinear Normal Modes

Abstract

The paper focuses on the design and analysis of state feedback controllers to control the amplitude of limit cycle oscillations (LCOs) for a nonlinear aeroelastic system. A nonlinear feedback control function without any linear terms is used to represent the closed loop system dynamics. Nonlinear normal modes are computed for the closed loop system using asymptotic method followed by application of harmonic balance method to estimate the amplitude and frequency of LCOs. The equations from harmonic balance are further differentiated with respect to control parameters to obtain sensitivities of LCO amplitude to the control parameters. The computed sensitivities are used in a nonlinear optimization framework to generate control parameters suitable to minimize the limit cycle amplitudes.