AN EQUATION DECOUPLING TECHNIQUE FOR IDENTIFICATION OF UNSTABLE AIRCRAFT WITH UNSTEADY AERODYNAMIC MODELING

A simplified trailing vortex concept has been used to model unsteady a erodynamic effects onto the mathematical model for an augmented unstab le aircraft. An output error method with, and without, an equation dec oupling technique in the frequency domain has been used for the estima tion of parameters. The two approaches of estimation are compared for the cases where unsteady effects are included or excluded from the est imation model. It is shown that the incorporation of the equation deco upling technique makes the estimation algorithm robust with respect to initial guess values of the parameters. Finally, the inclusion of uns teady aerodynamics is shown to reduce the variation in the parameter e stimates due to different control input forms.