Magnetic and Mechanical Modeling of a Soft Three-Axis Force Sensor

This paper describes the modeling of a soft three-axis force sensor. The sensor has a cylindrical cantilever beam made of silicone rubber that compresses and bends when normal and tangential forces are applied. The displacement of the beam's end is calculated by measuring the change of the magnetic field emitted by a permanent magnet embedded in the soft beam, at fixed points in space. Spring theory and bending theory are used to calculate the normal and tangential force components. The normal forces calculated by the proposed model and the measured values have an error less than 5% validating the analogy of the sensor to a soft cantilever beam under compression and bending. The proposed mathematical model is simple and faster than a finite-element model, and accurately represents the non-linear behavior of the sensor's physical effects to applied loads.