A Novel Position Sensor With a Conical Iron Core

Abstract

A novel position sensor for pneumatic and hydraulic cylinder applications is presented in this paper. The solid iron core conical in shape surrounded by axisymmetric coils is an essential part of the proposed position sensor. The axisymmetric coils are used for excitation and voltage measurements. The conical solid iron core is annealed to homogenize the magnetic properties and to increase the permeability of the conical solid iron core. This improves the performance of the position sensor in terms of sensitivity and linearity. Analytical and finite element analyses are utilized along with measurements in order to analyze the performance of the position sensor. The position sensor performs measurements of excitation coil inductance and pick-up coil voltages. Various frequencies are considered for the analysis and for the measurements. The measurement results show that the maximum linearity error is about 4% for the manufactured sensor, and is calculated to have a maximum value of 1% for the theoretical model. The achievable resolution of the proposed sensor is about 0.4 mm.