Design of Reconfigurable Actuation in Tendon-Driven Robot Hands: Analysis of Potential and Challenges

The idea to handle multiple degrees of freedom (DOF) in robot hands using fewer actuation is present since early robot hand designs exist. For that purpose, underactuated mechanisms (UMs) have become basic understanding. Some UM designs allow actuation of the complete hand with a single input. Besides many advantages of such an application, only a limited set of grasping patterns can be accomplished. In such a design, all DOF are mechanically linked. For some grips, required DOF are either not included or contradictory actuated. A UM that allows to vary the linked DOF could solve the deficit. However, to the best of our knowledge, such a mechanism has not been presented yet. This work presents a mechanism that actuates up to ten tendons with a single input. The design allows to freely choose the tendons that need to be actuated and to lock them in their state to enable preconfigurations for specific grasping patterns. Besides the implemented prototype, further principal design options for a reconfigurable mechanism are discussed regarding their challenges and potentials, based on given examples.