Active disturbance rejection controller for flutter suppression with time-varying delay

Abstract Current research on active flutter suppression considering time delays tends to focus on fixed time delays. To address situations where the control loop may experience time-varying delays with uncertainty, a time-varying-delay Active Disturbance Rejection Control (TVD-ADRC) is proposed. First, a parameterized unsteady aerodynamic reduced-order model (ROM) based on a long short-term memory network is introduced into the aeroservoelastic modeling. This model is applied to predict unsteady aerodynamic forces and aeroservoelastic (ASE) behaviors across a wide range of Mach numbers. Its effectiveness in capturing the characteristics of unsteady aerodynamics is validated through comparisons with the high-fidelity computational fluid dynamics (CFD) simulations. Second, the proposed method integrates ADRC with a delayed input and a time-delay identification module in the controller design. Specifically, the time-varying delay is identified using the cross-correlation function method with a moving window, and this method dynamically updates the time-delay compensation module. Additionally, a genetic algorithm is employed to optimize controller parameters, and the integral of the time-weighted absolute error is selected as the performance evaluation index for the control system. Finally, a three-degree-of-freedom aeroservoelastic system of an airfoil with a trailing-edge control surface is studied for flutter suppression. Flutter control under uncertain time-varying delays during flutter occurrence is investigated, and the impact of the magnitude of the time delay on the effectiveness of the flutter control is analyzed. Simulation results indicate that the proposed TVD-ADRC controller could effectively suppress the aeroelastic instabilities across a wide range of Mach numbers and effectively counteract the negative effects of time-varying delays.