Development of Strain-Deformation Expansion Mechanism with Flexure Hinges for high precision and high sensitivity torque sensing

This paper proposes a strain-deformation expansion mechanism with flexure hinges for joint torque sensing. By the torque sensing mechanism, the small strain-deformation on a joint used for torque sensing can be expanded while the sensor stiffness will not be reduced but will be heightened. For the mechanism, a novel flexure hinge with two overlap semicircular notches, where there are no friction and gap which are often existing in a rotational hinge, is proposed for preforming high-precision sensing. In this paper, the force sensing principle is addressed by analyzing the deformation of the sensing mechanism and the forces acting on the sensor theoretically. Then, the sensitivity of the sensing mechanism are defined, and a design method for realizing the sensing mechanism with high sensitivity is discussed. Lastly, some experiments with robot finger are performed to show the basic characteristics and the effectiveness of the proposed joint torque sensing mechanism.