Modeling of Torsional Compliance and Hysteresis Behaviors in Harmonic Drives

Nonlinear torsional compliance and hysteresis are associated with harmonic drives, and their accurate modeling is crucial for improving performance of the control system of harmonic drive-based devices such as robot joints. In this paper, a new approach is taken to model the torsional compliance and hysteresis behavior in harmonic drives. The proposed model is derived by modeling the compliance behavior of the flexspline and the wave generator instead of modeling the individual behaviors of the overall harmonic drive transmission. The hysteresis loss is captured by taking the wave generator torsional compliance into account. The proposed model is validated through numerical simulations and subsequently with experimental data.