Understanding and Modeling the Behavior of a Harmonic Drive Gear Transmission.

摘要

As harmonic-drive transmissions find increased use and acceptance among engineers and designers, the demand for an accurate and reliable understanding of harmonic-drive operating behavior becomes great. In my research, I have performed an extensive experimental investigation of harmonic-drive properties such as stiffness, friction, and kinematic error. From my experimental results, I have confirmed that kinematic error appears primarily at frequencies that are multiples of the wave-generator rotational speed and that transmission stiffness can be highly non-linear. Additionally, measurements of static and dynamic friction demonstrated that energy dissipation in harmonic drives varies non-linearly with velocity and periodically with rotation and can escalate during system resonance. Due to the interaction of these transmission properties, dynamic response measurements showed surprisingly agitated behavior, especially around system resonance. This behavior Was rationalized in terms of the observed properties and used to develop dynamic models to describe harmonic-drive operation. From these models, I realized that non-linear frictional effects cannot be ignored in any accurate representation. Additionally, if behavior around system resonance must be replicated, both kinematic error and compliant behavior are essential.