A non-linear model of a complex system using variable parameters

The presented article is aimed at the analysis of precision of a non-linear mathematical model of a small turbojet engine iSTC-21v. This precision is dependent on accuracy of the model's gain approximation methods (polynomial, interpolation, Fourier, etc.), which are investigated in the article. The hypothesis of the paper is if it feasible to achieve very high level of accuracy in this approximation and if the resulting non-linear dynamic model will be more useful in control. This is important to research in order to comply with demands on control systems in aviation like safety, reliability, while maintaining simplicity. Verification of the models has been done using the measured data from a small turbojet engine in laboratory conditions.