Identi cation and Control of Limit Cycle Oscillations in Aeroelastic Systems

Nonlinearities in the aeroelastic system induce pathologies such as the observed store-induced limit cycle os-cillations found with certain high-performance aircraft con gurations. Many previous studies, including efforts by these authors, focus on the nonlinear behavior of the uncontrolled, nonlinear aeroelastic system. These studies are brie y reviewed. However, there is limited study of the active control of these nonlinear aeroelastic systems. Although a linear controller may stabilize the nonlinear system under some circumstances, empirical evidence suggests that these control methods will prove unreliable in strongly nonlinear regimes and that stability is not guaranteed. The development of control strategies appropriate for these nonlinear systems are described. A non-linear controller and the resulting closed-loop stability based on a partial feedback linearization are discussed. The approach depends on the exact cancellation of the nonlinearity. Hence, an adaptive control method is introduced in which guarantees of stability are studied. Experimental results obtained using the adaptive control system are presented