Lateral Flight Dynamic Controller for Flexible BWB Aircraft

Two different approaches for design of lateral control augmentation system for large blended-wing-body aircraft (BWB) with flexible structure are presented and asses in this paper. The most challenging issue is handling of rigid-body dynamics and flexible modes coupling. First, a more classical approach is employed giving rise to separate flight dynamics controller (H2 optimal, with sufficient roll-off) and an active damper for most prominent lateral flexible modes on top of that (mixed-sensitivity H∞ design). This approach proves successful and has obvious advantages related to the design process complexity, or implementation and testing issues. On the other hand, there is always a risk of potentially significant performance loss compared to a fully integrated design. For this reason, fully integrated design is also presented in the form of a fixed-order MIMO H∞ optimal FCS controller, obtained by means of direct non-convex non-smooth optimization package HIFOO. Performance of both approaches is assessed.