IDM-Assisted Capacitive Displacement Sensor for Large-Range, High-Precision Positioning Systems

This study proposes a novel impact driver mechanism (IDM)-assisted displacement sensor based on the time-sharing-control-based measurement method and the IDM-assisted mechanism. This innovation enables traditional capacitive displacement sensors to break through their range limits and to be used for feedback control in the positioning system of precision instruments, such as scanning probe microscopes and astronomical telescopes. To allow the IDM to drive a larger mass sensor probe, a flexible isolation structure is designed based on the dynamic mass isolation principle and together form the IDM-assisted probe. The IDM-assisted probe together with the combination fixture form the IDM-assisted mechanism. Through the utilization of the time-sharing-control-based measurement method, the IDM-assisted displacement sensor achieves a large measuring range by working in synergy with the positioning system. The IDM-assisted sensor is designed and manufactured. Experimental results show that the IDM-assisted sensor can achieve displacement measurements with a resolution of 0.3 nm
$_{\mathbf{RMS}}$
and a range of 1.6 mm. The IDM-assisted sensor has been applied to the feedback control of a designed positioning system and experimental results have shown that it effectively improves the nonlinearity of the positioning system, reducing it from 10
$\% $
to 1
$\% $
.