Static Analysis of Single-Input/Multiple-Output Tendon-Driven Underactuated Mechanisms for Robotic Hands

Considering the many advantages of underactuation in anthropomorphic hands, such as lightness, ease of control and compactness, it is of interest to develop mechanisms that aim at achieving underactuation between the fingers. This paper presents several tendon-driven underactuated mechanisms that can drive four outputs from one input. These mechanisms could typically be used to drive four fingers of an underactuated hand from a single input. Among these mechanisms, some are built by combining one-input/two-output differential mechanisms, while others are fully integrated systems of pulleys. For each mechanism, a static analysis is presented. Then, a discussion based on the static analysis and experimentation on models highlights their strengths and weaknesses. Finally a new anthropomorphic hand used as an experimental platform to test these mechanisms is introduced.