Active stall flutter suppression for a revised Leishman/Beddoes model

This paper proposes a nonlinear disturbance observer (NDO) based sliding mode control (SMC) method to the problem of stall flutter suppression for a revised Leishman/Beddoes (L/B) model. To capture accurate aerodynamic characteristics whilst reducing the plant model mismatch, the dynamics of the separation point and the shift of the aerodynamic centre are analysed to improve the structure of the L/B model. Based on this revised L/B model, an active flutter suppression problem which includes aerodynamic disturbances and actuator dynamics is addressed. The inclusion of the actuator dynamics means that the aerodynamic disturbance from the flow separation, induced by the revised L/B model, is considered as an ‘unmatched’ disturbance. To counteract the effect of unmatched disturbances, an NDO-based sliding mode control scheme is applied to suppress stall flutter and to ensure rapid reference tracking performance in both steady and unsteady flow conditions. Simulation results show the improvements of the proposed revised L/B model via a comparative analysis. In addition, the efficacy of the proposed stall flutter suppression scheme is demonstrated