Abstract

To directly measure the ground reaction forces (GRFs) acting on the foot, force sensors are often placed on an insole. For this purpose, the force sensors should provide both precise measurement and flexibility for the minimal discomfort. In this paper, design of an elastomer-based force sensor is proposed for the minimal hysteresis and improved precision. The sensing mechanism based on the internal pressure change of an air passage in the elastic structure. The elastomer of the sensor is designed considering several practical requirements; to minimize the hysteresis phenomena of the sensor, three materials, which are normal, room temperature vulcanization (RTV) silicone rubbers, are considered and tested. Through multiple iterations of fabrication, RTV silicone rubber, which has the least hysteresis, is chosen for elastomer of the sensor. Least-square curve fitting based on experiments is performed to compensate for the nonlinear behavior of the sensor. Basic sensor properties including operation range, repeatability and resolution are assessed through the verification experiment.