Published online by Cambridge University Press: 04 July 2016
This paper describes the results of a study focusing on the possibility of identifying nonlinear helicopter models in the time domain. In recent years, identification techniques working mainly in the frequency domain were applied to estimate the parameters in helicopter models. Recently, the time domain identification method of the DLR was improved to allow the identification of fully nonlinear models. To investigate the applicability of this method to helicopters, a nonlinear derivative model with explicit equations for the individual blade flapping angles was formulated. In comparison to the linear derivative models nonlinear models are physically more realistic and are not restricted by small perturbation assumptions. Although a large number of unknowns had to be determined, a nonlinear model was successfully identified.