Linear Controller Design for an Equivalent Dynamic Model of a Typical Ducted Fan Air Vehicle in Hover, Using Frequency Response Identification

In this paper, firstly a linear model of the ducted fan air vehicle is is derived from the non-linear dynamic model of the system, using frequency response analysis. A power spectral density analysis is is performed to evaluate the input-output responses in hover flight and also to derive the transfer functions based on the coherence criterion. Then, to evaluate the accuracy of the identified transfer functions, ram-step responses of the derived transfer functions are are compared with those of the a-nonlinear system. Attitude controllers are are_also designed usingby utilizing the identified transfer functions, and—andadditionally, the effect of saturation existence in the closed-loop identification process is is assessed.