关键词: 颤振抑制, 时滞系统, 反馈控制, 跨声速, 降阶模型, 间隙非线性

Abstract: In active control of flutter, time delays are inevitably introduced and have significant influence on the stability of the closed-loop controlled aeroelastic system. At present, study on the flutter suppression has been focused on subsonic and supersonic regimes, where aerodynamic forces are modeled with the linear theory. However, it is noticed that civil or military aircraft usually cruise at the transonic regime, and the control surface deflection is used as a control variable in the active control. In view of the above situation, the method of time delay feedback control for free-play nonlinear system transonic flutter is developed based on the aerodynamic forces reduced order modeling. In the method, the unsteady aerodynamic forces models for transonic regime were firstly identified with the white noise as excitation signals, and were combined with free-play nonlinear structure model to construct the state-space models for the controlled aeroelastic system. Then, a state transformation with the integral item was introduced to make the input-delay system be transformed into a system without delay. Finally, optimum time delay feedback control is designed by optimum control theory. Simulation results indicate that, for the system with time delay, the control algorithm may fail to suppress the flutter if time delay is not considered in control design. The effectiveness of the proposed time delay feedback control algorithm isn't influenced by the magnitude of the time delays. The developed method can obtain excellent flutter suppression results with either small or large input time delay.

Key words: flutter suppression, time delay system, feedback control, transonic, reduced-order model, free-play nonlinearity