Friction microdynamics in the time and frequency domains: Tutorial on frictional hysteresis and resonance in precision motion systems

This paper provides an overview and tutorial on the key behaviors of mechanical friction in both the time and frequency domains to understand friction effects on precision motion control systems, and presents implications of this behavior for high-precision applications. Friction behaves differently depending on the operating regime. In the steady sliding regime, friction is a function of the relative velocity of two objects sliding against each other, and characterized by static, Coulomb and viscous terms. We observe more complex frictional behaviors as the velocity and displacement are near zero, which is the pre-sliding regime. Friction in this regime depends on the displacement of objects in contact, acting as a nonlinear hysteretic spring. In this paper, we focus on the time- and frequency-domain phenomena caused by the nonlinear hysteretic elasticity of such pre-sliding friction. Frictional microdynamic behaviors in each domain are experimentally studied with a servomotor system testbed and using the Generalized Maxwell-Slip (GMS) friction model. Friction model identification methods based on experimental observations are also discussed in both the time- and frequency-domains. We also present structures for accurate time-domain simulation of friction.