A Study of the Input-Output Hysteresis of the Magnetostrictive Torque Sensor with Phase-Sensitive-Detection

Abstract

A mechanism of the input-output hysteresis is analyzed for the magnetostrictive shaft torque sensor with phase-sensitive-detection technique. The origin of the hysteresis is the magnetic hysteresis between the applied torque and the permeability of the magnetostrictive shaft material, hence, the impedance of the pickup coil coupled to the shaft surface. The shape of the input-output hysteresis, which is the hysteresis of the output voltage converted from the impedance of the pickup coil by the phase-sensitive-detector, changes with excitation condition. Under a certain excitation condition, the input-output hysteresis becomes zero for the torque sensors constituted with a class of steel shafts.