Design of a Force Sensor for Thigh Force Measurement of a Wearable Walking Robot

Abstract

We describe the design and fabrication of a three-axis force sensor with parallel plate beams (PPBs) for measuring the force of a patient’s thigh in a wearable walking robot. The thigh link three-axis force sensor is composed of Fx force sensor, Fy force sensor, Fz force sensor and a pulley, which detect the x, y and z direction forces, respectively. The threeaxis force sensor was designed using the Finite Element Method (FEM), and manufactured using strain-gages. Experiments to evaluate the characteristics of the three-axis force sensor were carried out. The results of the characteristics experiment indicate that the repeatability error and the non-linearity of the three-axis force sensor was less than 0.04%, and the results for calibration showed that the errors of the sensor was less than 0.1%. Therefore, the fabricated thigh link three-axis force sensor can be used to measure the patient’s thigh force of the wearable walking robot.