An Optical Torque Sensor for Robotic Applications

In this article, the design and the experimental evaluation of a torque sensor based on optoelectronic components integrated in a suitably designed plastic compliant frame are reported. The sensing principle is based on the variation of the photocurrent flowing through a PhotoDetector (PD) as a consequence of the variation of its relative position, with respect of a Light Emitting Diode (LED), caused by the deformation of the sensor frame under the effect of the torque to be measured. The sensor frame has been designed as a planar structure that shows preferential deformation along a rotation axis normal to the symmetry plane. This article reports the sensor basic working principle, the compliant frame design and verification, the calibration of the sensor, and the experimental evaluation of its sensitivity and frequency response.