High stiffness capacitive type torque sensor with flexure structure for cooperative industrial robots

In this paper, a capacitive type torque sensor for cooperative robot manipulators is proposed. Flexure structures are used to increase its sensitivity while maintaining the high stiffness between input and output. The sensor can measure external torque of the joint by sensing capacitance of the parallel electrode plates which are attached to the flexure structures. Symmetrically placed 4 sets of electrodes can compensate the torque ripples caused by harmonic drive gears and absorb undesired off-axis moments. The basic concept and detailed design are presented and the experimental results of the implemented sensor are shown.