Based on a feedforward controller for attenuating the unsteady aerodynamic roll moment disturbances on a UCAS delta wing platform,1 a feedback loop is added to the control system to correct the error in the controller. A black-box model for the plant is identified and used in the design of the feedforward loop. The disturbance model is identified through the same linear model identification approach. The open-loop feedforward controller is evaluated in real-time wind tunnel experiments under unsteady flow conditions in which the flow speed surges longitudinally. The wing is fixed at 15-degree angle of attack with a constant roll angle of -30 degrees. The changing roll moment due to the unsteadiness of the flow and the sideslip on the wing is predicted by surface pressure measurements from fourteen pressure sensors distributed on the upper surface of the wing. The measurements are used as a surrogate signal for the roll moment, which measure both the active flow control effect and the disturbance from the surging flow. The complete closed-loop controller is examined in real-time control cases, including sinusoidal and pseudo-random surging flows.
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