Reduction of Structural Mode Interaction for FSC/Structural Design Integration

The proposed SBIR project is to carry out research into a novel way of reducing the degree of structural mode interaction between a flight control system and the airframe vibration modes. This can be a severe problem in high performance military or civil aircraft with high gain feedbacks in the system. The conventional approach to this problem is to use notch filters, but the resulting additional phase lags can give rise to difficulties in meeting the low frequency pilot handling quality requirements. The proposal describes the concept for a novel approach to the problem that could lead to a significant advance in treatment of structural mode interaction, without the adverse effects on handling qualities. The proposed work program is to conduct a theoretical evaluation using representative aircraft data, including an assessment of the robustness of the approach with data uncertainties. An initial specification and design of a laboratory test rig is planned, which would be used for a practical evaluation of the techniques in a Phase II program. The technology and algorithms resulting from research into the concept should form a product that can be exploited commercially.