A multi-model and multi-objective approach to the design of helicopter flight control laws

Abstract

This study addresses the design of a full-authority Attitude Command-Attitude Hold flight control system for the Bo-105 helicopter. The usual PID-based arrangement is replaced by a single 6th-order dynamic controller. The proposed design methodology combines multi-model and multi-objective approaches within the framework of structured H¥ software tools. Owing to the multi-model approach, only two sets of gains are sufficient to cover the entire speed range between hover and maximum velocity. In addition, ?-analysis tools can be used in conjunction with this approach to improve robustness against parametric uncertainties. Simultaneously, the multi-objective approach facilitates the design process and establishes connections between the tuning parameters and handling qualities. The performance of the resulting flight control system is investigated in this study, and evaluated against the attitude quickness, bandwidth and inter-axis coupling criteria, as defined by ADS-33. The resulting design achieves Level 1 performance in most cases. Besides, the merits and limitations of the proposed methodology are discussed in this paper.