Based on the working principle of the capacitive sensor, according to the requirements of deep hole diameter measuring, a capacitance probe sensor was designed, and then the design and type-selection of probe structure, cable inner structure to the capacitance probe sensor were done. At the same time, in order to overcome the measurement error caused by eccentricity, the capacitance sensor probe and inner hole of the corresponding fastener both are designed to a taper, taper positioning is relatively accurate positioning way. The design is to avoid the measurement position offset, and ensures the coaxality on the mechanical structure. The equipotential ring technology effectively overcomes the problem of edge effect of capacitance sensor, and makes the probe’s effective measurement electrode under the condition of limited long, can effectively guarantee the measure precision. By moving the capacitance probe in the hole to the different position, we will realize the deep hole diameter measurement in different cross section.
