Design and Fabrication of a Contactless Hybrid Static Magnetostrictive Force-Torque Sensor Using Galfenol

This paper presents a novel Contactless Hybrid Static Magnetostrictive Force-Torque sensor using Galfenol. Initially, the sensor's design principles in axial force and torque measurements are described. The magneto-mechanical properties of used materials, such as B-H curves and magnetic permeabilities are measured under various mechanical preloads and magnetic fields and improved in some cases. These properties are used in finite element method. The sensor is evaluated numerically using COMSOL Multiphysics® software based on the obtained experimental results. Afterward, the sensor is fabricated based on finite element method results and experimentally tested in different electrical currents and excitation frequencies. Sensitivity, repeatability and linearity errors are presented separately in force and torque measurements in optimal operating condition of the sensor. Then, the finite element method results are verified with the experimental results. Finally, the performance characteristics of the sensor in optimal conditions are presented and it is found that the sensitivity increases while increasing the electrical current (or magnetic field) and frequency. The maximum sensitivities for axial load and torque measurements are obtained at 0.7349 mV/kgf and 2.24 mV/N.m, respectively.