Frequency domain identification of an aircraft LFT model

The aim of this paper is to identify an LFT model of a rigid aircraft. The highly structured aerodynamic model is first put under a standard LFT form, in which the uncertain parameters are gathered inside a full real block Δ. Time domain measurements are then translated into frequency domain ones, using a classical FFT technique. Under a rank condition which is satisfied in our aircraft application, inputs and outputs of the model perturbation Δ can be deduced from the physical aircraft inputs and outputs, so that Δ can be identified using either a Robust Least Squares method, or an output error set-membership identification technique.