Wing rock control by finite-form adaptation

Abstract

The wing rock (self-excited rolling motion) of aircraft flying at high angle of attack adversely affects the handling qualities and maneuverability. This paper presents new adaptation algorithms in finite (integral-algebraic) form for the wing rock control. The objective is to stabilize the rolling motion, despite parameter uncertainties. Two adaptive control laws in finite form are derived for the trajectory control of the roll angle. The first control system is obtained by the realization of a speed-gradient adaptation law, and an immersion and invariance-based adaptive law is used for the second controller. Unlike the certainty-equivalent control laws, these adaptation laws include an integral term as well as a judiciously chosen nonlinear algebraic vector function. The algebraic function in the adaptation law provides stronger stability properties in the closed-loop system. Simulation results show that the designed adaptive controllers are capable of suppressing the wing rock motion of the model, despite uncertainties in the parameters.