Identification and modeling of contact dynamics of precise direct drive stages

The aim of this paper is to develop identification that is capable of capturing the characteristics of nonlinear tangential elastic and friction forces arising in submicron 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 140 Hz. The identified elastic force incorporates the inevitable nonlinear nature of the stage. 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.