Low Order Model Approximation of Aeroelastic/Aeroservoelastic System

In this paper, a system identification technique for low order model approximation of Aeroelastic / Aeroservoelastic system is introduced. The ORThonormal Finite Impulse Response (ORTFIR) filter is applied to approximate the Aeroelastic / Aeroservoelastic system. The advantage of using orthonormal bases in the ORTFIR filter lies in the possibility of incorporating prior knowledge of the syst em dynamics into the identification process. As a result, more accurate and simplified linear models can be ob tained with a limited number of basis functions. Two stages are considered during the estimation process. At the first stage, the physical modal information of the Aeroelastic / Aeroservoelastic system is extracted with the use of the frequency domain Polymax identification methodology and the stabilization diagram; at the seco nd stage, the extracted modal information is imported to generate the basis functions, and thereafter, a standard least square algorithm is used directly to estimate the coefficients of the ORTFIR filter. A F/A-18 AAW case study is presented to demonstrate the proposed identification technique.