Fuzzy Logic for Control of Roll and Moment for a Flexible Wing Aircraft

Abstract

A fuzzy logic-based, multi-input/multi-output roll controller has been designed for Rockwell International's Advanced Technology Wing (ATW) aircraft model. The ATW integrates active controls with a flexible wing structure to provide wing shapes that optimize particular flight performance criteria. Because of the large variations in the dynamic model of the wing as a function of flight condition, the use of a fuzzy controller was investigated for roll rate and load alleviation control. Fuzzy rules were developed to determine the appropriate control surface deflections to achieve the desired roll rate while ensuring wing loads are within safe bounds. A novel departure of the rules from conventional control heuristics is in the modulation of damping factor according to the distance of the system state from the goal state. This damping modulation technique enables full utilization of the vehicle's acceleration capability and resulted in an improvement of the response time by a factor of two. When the wing loads are close to the bounds, control rules derived from a qualitative analysis of the plant model provide load alleviation with minimal degradation in roll performance. The resultant fuzzy controller commands six surface deflections to control the roll rate and four torsion moments. © 1991 IEEE