Modelling and Parameter Identiication of Harmonic Drive Systems

The unique performance features of harmonic drives, such as high gear ratios and high torque capacities in a compact geometry, justify their widespread industrial application, especially in robotics. However, harmonic drives can exhibit surprisingly more complex dynamic behavior than conventional gear transmissions. In this paper, a systematic way to capture and rationalize the dynamic behavior of the harmonic drive systems is examined. Simple and accurate models for compliance , hysteresis, and friction are proposed, and the model parameters are estimated using least{squares approximation for linear and nonlinear regression models. A statistical measure of variation is deened, by which the reliability of the estimated parameter for diierent operating condition, as well as the accuracy and integrity of the proposed model is quantiied. Finally, the model performance is assessed by a simulation verifying the experimental results on two diierent harmonic drives.