Development of a three dimensional scanning touch probe with high precision and low contact force

摘要

This study aims to develop a three dimensional scanning touch probe with high precision and low contact force.The overall design has two parts,mechanism design and optical path design.The mechanism design contains three parts,Zaxis system,XY-axis system,and probe mechanism.The Z-axis system applies the characteristic of the thin sheet spring to move vertically.In the design of XY-axis system,a micro-beam is employed,through which length,width,thickness of the micro-beam and corresponding dimensions of the leaf spring are designed according to the selected contact force.The freedom degree is limited to three.And the center of the mechanism is equipped with a stylus to inhibit displacement of the Z-axis.The contact between the probe and the workpiece only leads to change in the angles of Xand Y-axes,achieving the feature of 2-degree freedom.To enable rapid change for the probes,this study designs a probe mechanism,reliability of which is analyzed and validated with ANSYS software,so that the design of 3-degree freedom mechanism is completed.The sensor has a laser diode to coordinate with Position Sensor Detector (PSD) which works with the optical path designed to measure placement of Z-axis and angle placement of XY-axis.By validation through an experiment,the three dimensional scanning touch probe developed by this study has a measuring range of ±1mm×±1mm×1mm,and unidirectional repeatability of 0.6um.