Aeroservoelastic Wind Tunnel Evaluation of Preview H2 and H8 Gust Load Alleviation

Studies of preview gust load alleviation H-2 and H-8 controllers via synthesis, simulation, wind tunnel tests, and test/simulation correlation are presented in this paper. University of Washington active aeroservoelastic wind tunnel model design, construction, and testing capabilities are used. The test article is a flexible half wing-body-tail model with active control surfaces of two ailerons and an elevator. The model moves in a combination of rigid-body and elastic motions. The commands of gust vanes are used both to generate gusts and to provide real-time preview gust encounter information. A discrete-time linear-time-invariant output feedback system is augmented with various preview lengths of information. The experimental results show that gust loads are reduced with gust preview information compared to feedback-only control and are halved with the fullest gust preview information compared to the open-loop case. The wind tunnel results validated the simulations and added insights to the performance of preview H-2 and H-8 control implementation. The closed-loop analysis quantified the margins and robustness of the systems and correlated with the time history of both simulations and experiments. This paper presents preview gust load alleviation robust control test results, not available so far, in a realistic experimental setting.