Robust frequency identification of oscillatory electromechanical systems

The paper deals with identification of electromechanical systems with oscillatory dynamics. Swept sine signal is chosen for excitation of the system and time-varying observer is used for estimation of its frequency response. Practical implementation issues for various mechanical configurations typical for industrial applications are analyzed and concept of frequency-separated semi-closed loop identification is proposed. Adaptive algorithm which suppresses nonlinearities of the system due to mechanical friction and estimates actual quality of measurement is derived. The identification method is demonstrated on an example of two-mass oscillatory system with nonlinear load-side friction characteristics.