Multi-input/multi-output adaptive active flutter suppression for a wing model

The work develops and verifies experimentally a multi-input/multi-output adaptive active putter suppression system for a built-up wing model fitted with a leading-and a trailing-edge control surface and two accelerometers. An indirect adaptive scheme, combining an identification of a discrete dynamic model followed by the design of a stabilizing control law, has been used. The identification is based on a recursive multivariable-extended least-squares approach applied to the input/output relations connecting the accelerometer signals to the control surfaces deflections, while the stabilizing controller is designed by a full-state eigenstructure assignment method. The order and structure of the control system and the tuning of its design parameters have been carried out through extensive numerical simulations aimed at the determination of an optimal compromise between system performances and computational requirements. The adaptive controller thus obtained was implemented on a wing model and tested in a wind tunnel by using two loosely coupled cooperating personal computers, one for the position servos of the control surfaces, the other for the indirect adaptive flutter suppression. The tests have demonstrated that the system is capable of achieving a significant increase of the subcritical aeroelastic damping and of the flutter speed of the wine model.