Drive-Based Identification of Transfer Function Between External Load and Motor Torque on Electromechanical Axes

Drive-internal signals of electromechanical axes offer great potential for higher-level machine monitoring. In addition to fault diagnosis of the mechanical and electrical subsystems, those signals can be used for estimating time-variant external loads. Therefore, it is an essential prerequisite to determine the transfer function between load torque and servomotor. Almost all available methods have in common that the required models are either identified using external measurement and excitation sources or limited in their accuracy. The paper presents an alternative approach by providing the required excitation by the servomotor itself and use only available signals of the drive system. The experimental results on a single-axis test rig prove the functionality of the proposed method.