Characterization of finger joints with underactuated modular structure

The characterization of flexible joints of robotic underactuated fingers allows the investigation of the finger flexion trajectories using a tendon-driven actuation. In this paper, the characterization of TPU 3D printed joints used in underactuated robotic fingers, is experimentally and numerically performed. Since the mechanical properties of 3D printed materials are uncertain, this research helps to define the characteristics of robotic fingers in terms of stiffness. The role of the stiffness for the control of fingers’ trajectories is fundamental and the obtained results are very useful for improving the method to track a certain predefined trajectory. Experimental and theoretical results evaluate the stiffness as a function of the infill density percentage of the material.