Authors : J. Cesar Castellanos, F. Carlos Suárez and E. Jorge Sofrony
Abstract: This article presents an L1 Adaptive Control technique to solve the wing rock stabilization problem which is described as a second order nonlinear system. The wing rock phenomenon is characterized by the appearance of a limit cycle in flight dynamics, caused by flow asymmetries that build nonlinear aerodynamic roll damping. The problem has been treated in the literature using L1 Adaptive technique, but several questions arise, especially in the way the prefilter is chosen such that the resulting augmented system is in fact L1 and guarantees closed loop stability under actuator and model dynamicsuncertainties. It is found in this article that L1 first order filters used in the simulations reproduce results of referenced authors but higher order L1 filters used, generate unstable response, even though the calculation of named L1 Norm Condition, considered in L1 adaptive control theory as necessary and sufficient condition is met which is an exception to the theory. It is shown also that the choice of a proper third order filter instead of an strictly proper render steady state response with stationary error. Two schemes for the same wing rock system dynamics are treated, reproducing results of referenced authors in this article but higher strictly proper L1 filters used, generate unstable response not reproducing others results.
J. Cesar Castellanos, F. Carlos Suárez and E. Jorge Sofrony, 2021. Review of L1 Adaptive Control for Solving the Wing Rock Problem. Journal of Engineering and Applied Sciences, 16: 296-303.