Design of a Noncontact Magnetostrictive Force Sensor Applied to Movable Objects

Abstract

This article proposes a noncontact magnetostrictive force sensor (NMASS) using a Permendur strip. In comparison with the use of coils in conventional magnetostrictive force sensors (MAFSs), this design employs two magnets and a Hall sensor to generate a magnetic field and detect magnetic field variations induced by applied forces, respectively. Moreover, an equivalent magnetic circuit model is developed to describe the behavior of magnetic flux in the sensor and is used for deciding the suitable magnetostrictive material parameters. Then, COMSOL simulations and experiments were conducted to verify the equivalent magnetic circuit model and the sensor’s operation. The sensor’s force sensitivity was 1.34 mG/N, and the linearity was calculated to be ±2.92% under the application of a 480 N force in the experiments. The proposed sensor exhibits the features of low power consumption, noncontact force sensing, and miniaturization. Therefore, this sensor could be applied to movable objects, e.g., tension sensing for conveyor belts, axial force detection for spindles, or additional load measurement for robot joint motors.