A novel 6-DOF force/torque sensor for COBOTs and its calibration method

This paper intends to design a 6-DOF force/torque sensor along with its readout circuit for collaborative robots (Cobots) working environment. There are two major technologies to develop by this paper. The first technology is the capability of sensing contact forces and torques by a newly-designed six degrees-of-freedom (DOF) force/torque sensor at a fast speed to facilitate feedback control towards anti-collision for the Cobots with wide measurement range, precision, with a smaller size and lower costs. For the force/torque sensor structure, the finite element method (FEM) is established. The sensor is designed and optimized based on finite element analysis (FEA) while “maximum likelihood estimation (MLE)” is utilized to increase accuracy in estimation of force/torque by using appropriate statistical model. The second technology is the anti-collision control. If the collision occurs, the Cobot has an ability to response safely and instantaneously. The proposed control scheme and assisting 6-DOF sensor are capable of performing Cobots anti-collision in welding, grinding, polishing, assembling, etc. with high precision.

Introduction

The act of measuring of force/torque is supreme in Cobots applications such as welding, polishing, grinding, assembling, holding objects or interaction between human and Cobots. While the most important approaches of torque/momentum measured dimension relate to resistive or/and piezoresistive strain gauge schemes, some of the contemporary approaches relate to principles such as infrared (IR) light, magnetoelastic, optical and SAW method stand for the surface acoustic wave method.