Multi-Objective Adaptive Control for Load Alleviation and Drag Minimization of Flexible Aircraft

This paper describes a multi-objective flight control system design for flexible aircraft to take advantage of the availability of multi-functional distributed flight control surfaces to simultaneously gain aerodynamic efficiency, maneuver and gust load alleviation, and aeroservoelastic (ASE) mode suppression while maintaining traditional pilot command-tracking tasks. A multi-objective optimal control design is developed to establish a reference model of the closed-loop plant to achieve simultaneously the four objectives: pilot command tracking, drag optimization, maneuver load alleviation, and ASE mode suppression. An adaptive gust load alleviation control is designed to estimate the gust disturbance for the disturbance rejection using a modified least-squares gradient adaptive law method. Simulations of the gust load alleviation and drag optimization control on NASA Generic Transport Model equipped with flexible wings demonstrate the effectiveness of the multi-objective flight control method.