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Metro450 Members Publications

Identification and modeling of contact dynamics of precise direct drive stages

13 April, 2016

Authors: Michael Feldman, Yaron Zimmerman, Michael Gissin and Izhak Bucher
Source: Journal of Dynamic Systems, Measurement, and Control, 2016



The aim of this paper is to develop identification that is capable of capturing the characteristics of nonlinear tangential stiffness and friction forces arising in sub-micron motions. Using novel Hilbert transform based signal processing and making use of the intimate relations between internal elastic and friction forces, the latter can be simultaneously recovered from measured data. The experiments were performed on a stage equipped with linear motors, while being driven by slow, quasi-harmonic excitation at frequencies of 1 to 40 Hertz. The identified elastic force incorporates the inevitable nonlinear nature of the stage, exhibiting preloaded and softening stiffness, alongside some viscoelastic behavior, which appears at higher frequencies. The experimentally identified nonlinear friction forces are successfully approximated by the Dahl's model, both with dry and viscous friction. The proposed identification technique can be useful for the analysis of modeling contact dynamics between moving and sliding parts in situ. This technique can possibly develop improved closed-loop control algorithms.