Active Flutter Suppression for a Three-Surface Transport Aircraft by Recurrent Neural Networks

This paper presents an effective approach for the design of a flutter-suppression system by means of recurrent neural networks. This system is used to move flutter instabilities outside the flight envelope of an unconventional three-surface transport aircraft. The design process requires a comprehensive aircraft model in which flight mechanics, structural dynamics, unsteady aerodynamics, and control-surface actuators are represented in statespace form, according to the modern aeroelastic approach. The implemented regulator is based on two recurrent neural networks: one is trained to identify the system dynamics and the other acts as a controller using an indirect inversion of the identified model. Keeping the training of both recurrent networks online leads to an adaptive control system. Extensive numerical tests are used to tune the neural network design parameters and to show how the neural controller increases system damping, widening the flutter-free flight envelope by more than 15% of the uncontrolled flutter velocity.