Active flutter suppression: non-structured and structured H∞ design

In this article a comparison of two controllers for the active suppression of flutter of a flexible remotely-piloted aerial vehicle is presented. The H∞ technique is used for both, but the first relies on the standard (non-structured) approach and the second on the structured synthesis. High-fidelity models derived from finite element modeling are used to verify the performance of the obtained controllers. Reduced-order models are used for the control synthesis, which are obtained from applying a combination of balanced and modal reduction techniques on the high-fidelity models. The results show that both controllers are similar in performance and robustness, and both are capable of suppressing flutter and extending the flight envelope well beyond the open-loop flutter speed.