Optical Sensor for Angular Position Measurements Embedded in Robotic Finger Joints

This paper presents the modeling and the design of an innovative angular position sensor able to be easily integrated into miniaturized robotic joints (a joint is mm large with a diameter of mm). The sensor working principle is based on the modulation of the light radiant power flux that goes from an InfraRed light emitting diode (IR LED) to a photodiode (PD) through a thickness-varying canal integrated into the joint itself. The LED and the PD are fixed on one of the links that compose the robotic joint, while the canal is integrated into the other link. A model for the interaction between the optoelectronic components is presented, validated, and used to design a robotic joint with the embedded angular sensor. The robotic joint has been characterized and use to implement a complete robotic finger with four embedded angular sensors. The tendon-driven robotic finger has been calibrated and experimentally tested.