Influence of linear and nonlinear aerodynamic models on parameter identification for aircraft

The linear and nonlinear aerodynamic models are built to investigate the influence of the two models on the parameter identification results. The polynomial modeling method is used to establish the aerodynamic models while the existing dynamic model of aircraft and output error method in time domain are applied to identify aerodynamic parameters at low angles of attack. A comparison is made between linear model and nonlinear model in both mathematical and physical aspects. And the effect of the nonlinear term on the estimated parameters is analyzed. Results show that nonlinear aerodynamic model is more reliable than linear model at low angles of attack. The considerable deviation between the modeled outputs and measured data at 0–1 s is reduced by introducing the nonlinear term into the model. Moreover the differences between the identified results given by two models are mainly exhibited at the inflection points in the images of the aerodynamic coefficients.