Design and Experiment of a Cardan-Type Self-Decoupled and Self-Powered Bending Moment and Torque Sensor

The conventional force sensors suffer from dimension coupling and energy problems. In this article, a cardan-type self-decoupled and self-powered bending moment and torque sensor were proposed, analyzed, fabricated, and tested. The sensor was mainly composed of a bending moment deforming ring, two torque deforming sheets, and a cardan. The bending moment deforming ring withstood the bending force applied on the sensor individually. The torque deforming sheets bore the torque alone. The separation of the bending moment and torque was realized by the cardan. After that, the coupled bending moment and torque acting on the sensor were decoupled and measured, respectively. Two pieces of magnetostrictive ribbons were bonded on the bending moment deforming ring and torque deforming sheets in order to realize passive and wireless detection. A theoretical analysis of the sensor was carried out. The sensor was fabricated and the experiments were conducted. The experimental results showed that the coupling force separation accuracy of the sensor was over 98%. The sensor could work without an internal power supply for an unlimited time. The sensor shows the merits of self-decoupling, working passively, and wirelessly. The sensor can be potentially used to detect the coupled force on a cutting tool of a machining center.