A New Method for Detecting the Contact Point between a Touch Probe and a Surface

This paper deals with a newly developed touch probe which can directly detect the point between the surface of an object being measured and itself. The proposed method is based on the spherical potentiometer; that is, the probe ball is covered with a thin resistant film and four electrodes are symmetrically allocated on the upper part of the probe ball. By measuring the electric resistance between the four electrodes and the contact point, it is possible to determine where the point of contact is located on the probe ball. This paper describes the computer simulation for designing the probe, the development of the probe based on this principle, the system of measurement using the probe and a coordinate measuring machine, and an evaluation of the developed probe according to the results of experiments.