Indirect fuzzy adaptive control for active shimmy damping

In the context of aircraft, shimmy is an oscillatory phenomenon of the landing gear mainly due the tire dynamics and the landing gear structural dynamics. This phenomenon, which can result in severe structural damages of the landing gear, is here actively damped by an indirect fuzzy adaptive controller. The difficulties to model the ground/wheel interface require the use of an adaptive controller that can modify its behavior in accordance with the plant dynamics. Thus, the proposed controller uses a fuzzy system to estimate the plant dynamics, and then implements this estimate to generate the control law. Based on Lyapunov’s theory, it is shown that the proposed adaptive control solution guarantees that the tracking errors will asymptotically converge to zero even if approximation errors appear in the estimation. Simulation results show that the proposed control law creates a realistic control input which properly damps the oscillations. This work is supported by the European DRESS project (Distributed and Redundant Electromechanical nose gear Steering System).