Crosstalk calibration for torque sensor using actual sensing frame

Accurate load sensing is crucial to robots' performance of various tasks undertaken to assist workers. Most of the research on load sensing by robot manipulators has focused on improving force/torque sensor hardware. Torque sensors suffer from crosstalk, which cannot be compensated, not even through calibration. Thus, for minimization of crosstalk, torque sensors require precise machining and a complicated structure, which often increase costs. This paper proposes an alternative, novel calibration method. In this scheme, first, the compliance matrix of the torque sensor is obtained from sampling data, and then the location and scale of the actual sensing frame, in which crosstalk-free load sensing occurs, can be estimated. Using the proposed calibration method, the external load acting on the end-effector can be sensed accurately, even with relatively low-quality torque sensors. Experimental results show that measurement accuracy was significantly improved with the proposed method.