ANALYTICAL AND NUMERICAL LINEARIZATION OF THE FLIGHT VEHICLE NONLINEAR DYNAMIC MODEL IN THE PRESENCE OF WIND

In this paper, nonlinear mathematical dynamic model for standard unmanned aerial vehicle, Aerosonde was developed at low velocities in the presence of wind and then its linearized model was derived using numerical and analytical-numerical methods. These linearized dynamic models and nonlinear one were simulated and compared with each other. It was shown that analytical-numerical and numerical linear models with nonlinear dynamic model confirm each other adequately. It must be mentioned that analytical-numerical linear model more accurate and closer to nonlinear model than numerical linear model, because of errors in calculating numerical linear model due to hard nonlinearities. Achieved linear models can be used for control system design purposes. Worst-case linear model was obtained for aerodynamic coefficients uncertainties. It means that these linearized models can be used for obtaining required accurate nominal linear models and uncertainties to design robust control system