Design of tendon-driven robotic fingers: Modeling and control issues

This paper reports the modeling activities related to the development of an innovative tendon-driven robotic finger, designed as the fundamental element of a new biologically-inspired artificial hand. The finger is realized in plastic material by means of 3D-printing, a production process that allows a remarkable simplification of the mechanical design. Through 3D-printing, we were able to easily implement solutions that could be very difficult, if not impossible, to obtain with conventional manufacturing. A detailed simulation model of the robotic finger has been developed with the aim not only of designing and testing suitable control strategies for the finger, but also of investigating the benefits and the flaws of particular design solutions. As a matter of fact, this approach to design and realization of robotic fingers, that fulfills the requirements in terms of compactness, integration and simplified assembly, has a significant drawback in frictional phenomena on both tendons and joints. For this reason, an adapted LuGre friction model is proposed in order to simulate and study the finger behavior.