Experimental Nonlinear Control for Flutter Suppression in a Nonlinear Aeroelastic System

Shakir Jiffri, Sebastiano Fichera, John E. Mottershead, Andrea Da Ronch
2017 Journal of Guidance Control and Dynamics  
Experimental implementation of input-output feedback linearisation in controlling the dynamics of a nonlinear pitch-plunge aeroelastic system is presented. The control objective is to linearise the system dynamics and assign the poles of the pitch mode of the resulting linear system. The implementation includes (a) the unsteady effects of the aerofoil's aerodynamic behaviour, (b) the embedding of a tuned numerical model of the aeroelastic system into the control scheme in real-time and (c) the
more » ... l-time and (c) the use of pole-placement as the linear control objective, providing the user with more flexibility in determining the nature of the controlled response. When implemented experimentally, the controller is capable of not only delaying the onset of LCO, but also successfully eliminating a previously established LCO. The assignment of higher levels of damping results in notable reductions in LCO decay times in the closed-loop response, indicating good controllability of the aeroelastic system and also effectiveness of the pole-placement objective. The closed-loop response is further improved by incorporating adaptation so that assumed system parameters are updated with time. The use of an optimum adaptation parameter results in reduced response decay times. = reduced speed, / U b α ω V = scalar quadratic Lyapunov function used in adaptive theory x α = centre of mass of aerofoil section from rotation axis, normalised by b , rot S m b α (-) Abbreviations LCO = limit cycle oscillation
doi:10.2514/1.g002519 fatcat:rb5pgiyc5za4vnl7tbxitwek6u