Suppression of Nonlinear Wing-rock Oscillations by Adaptive Control with the Implicit Reference Model<bold> </bold>

Modern aircraft, operating in nonlinear flight regimes at high angle of attack often exhibit a limit cycle oscillation in the roll angle known as the "wing rock phenomenon." When the wing rock appears, the roll angle trajectory undergoes oscillations of growing amplitude and asymptotically converges to the stable limit cycle. The wing rock dynamics are represented by essentially nonlinear model, which parameters are varying in the wide range depending on the flight conditions (altitude, Mach number, mass of the payload, etc.) and the angle of attack. The promising approach of wing rock suppression and roll angle control under parametric uncertainty condition is an application of adaptation methods. In the paper, the simple adaptive control with the so-called "Implicit Reference Model" is applied for ensuring the smooth tracking the roll angle of the reference (desired) trajectory with wing rock suppression. The simulations are made for various angle of attack, showing the efficiency of the proposed method.<bold> </bold>