Stepping motion analysis of surface acoustic wave motor toward nanometer resolution positioning system

A mechanical model of a surface acoustic wave (SAW) motor's stepping motions ranging under 100 nanometers was constructed. The SAW motor had a compliance structure in its movable part to utilize nanometer vibration of SAW for friction drive. The compliance, however, resulted in the two-degree-of-freedom vibration behavior of the movable part. Based on the mechanical model, the system identification was carried out by means of FFT analyses and decay fittings to experimental data. The simulation with the identified model qualitatively represented the experimental results. For more accurate simulations, additional nonlinear effects should be implied to the model.