Two-degree-of-freedom robust controller for an autonomous helicopter

• Published in: 2003 American Control Conference; Denver, CO; USA; 4-6 June 2003 Vol. 2; pp. 993 - 998
• Main Authors: Tanner, O., Geering, H.P.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2003
• Subjects: Aerospace control; Automatic control; Control design; Feedback; Helicopters; Motion control; Open loop systems; Robust control; Testing; Transfer functions
• ISBN: 9780780378964; 0780378962
• ISSN: 0743-1619; 2378-5861
• DOI: 10.1109/ACC.2003.1239716

The aim of this paper is to introduce a flight control configuration of an autopilot for an unmanned small helicopter under hovering flight conditions and to show the results on a helicopter test bench. The flight controller is an attitude controller with a two-degree-of-freedom structure, which is cascaded with an additional position-control loop. Two different design approaches for the two-degree-of-freedom controller based on H(infinity) theory are presented and applied to the horizontal motion of the helicopter. In the first approach, the feedback controller and the prefilter are designed by shaping the closed-loop transfer functions and by using an H-infinity optimization procedure. The second method uses the H-infinity open-loop shaping approach for the feedback design with an extended scheme for the feed-forward path. Both controller designs are tested under difficult conditions at a helicopter test bench with a wind generator and compared to a state feedback controller.