Adaptive Control of Aircraft in Icing Using Regulation-Triggered Batch Least-Squares Identifier

Abstract

Extensive effort in controller design of aircraft systems is invested ensuring safe, stable behavior in spite of large parametric uncertainties. Particular attention is placed on anomalous flight conditions harbored by the atmosphere, especially icing. This paper presents a regulation trigger-based adaptive controller to cope with the impact of ice on the aircraft equations of motion and to control the aircraft pitch to the commanded angle. For a pitch model of an aircraft system with the impact of icing, the design of a stabilizing certainty-equivalence controller using backstepping is first given, and it is succeeded by the introduction of a regulation-triggered batch least-squares identifier. A theorem is incorporated that guarantees that 1) pitch angle and pitch rate converge to the setpoint asymptotically, and 2) parameter estimates end after a finite number of switches. Finally, simulation results of an aircraft experiencing icing demonstrate the effectiveness of the identifier, with the trajectory of the iced system using the proposed identifier closely following that of the nominal system.