A Joint Torque Sensor for Robots

Abstract

This paper describes the design of the elastic body of a new torque sensor to measure torsion moment faithfully in the presence of strong overhang and thrust forces as well as bending moments. This feature, in conjunction with high stiffness makes this sensor an ideal choice for robotic applications. The structure inherently exhibits minimum strain sensitivities and compliances to all non-torsional moments and forces such that their effect can easily be cancelled in the Wheatstone bridge circuit. On the other hand, maximum possible local strain sensitivity near the material limit, and maximum torsional stiffness are achieved through the structure 's strain concentration characteristic. Several other important design criteria are also discussed, as well. The sensor geometry is analysed and further optimized using the finite element method. The sensor was constructed, and experimental data validated the finite element model and documented the sensor's performance.