Modeling of compliance and hysteresis with erasure property in harmonic drive by active loading

In order to understand compliance and hysteresis in harmonic drive better, an improved model considering the erasure property and a corresponding measurement method are proposed. Firstly, the polynomial fit and hereditary integral were applied to model the nonlinear stiffness and hysteresis behavior in harmonic drive. As the critical point of system energy discharge is the local torsional angle extremum, the hereditary hysteresis model was improved by replacing the global torsional angle extremum with the local extremum. Then the active loading method by a torsion bar with double motors was used to measure the hysteresis loop. Through this test data, the model parameters were identified by the least square method, and the precision of this compliance and hysteresis model was verified through experiments. Furthermore the erasure property of hysteresis in harmonic drive was captured by the improved hereditary model and this improvement was verified by a unilateral attenuating loading test. The presented work could serve as a theoretical reference to design a high precision control of harmonic drive in the electromechanical system.