Coupling Mechanisms for Multi-Fingered Robotic Hands with Skew Axes

The design of wristed, multi-fingered robotic hands for specific tasks usually leads to solutions in which the position of the joint axes have little to do with those of anthropomorphic hands. Joint axes tend to be skewed, which makes difficult the location of the physical joint along the axis. In addition, transmissions that work smoothly with parallel or perpendicular axes may not work well with skew axes. In this work, we present the optimal design of a simple five-fingered hand, consisting of a wrist joint and five fingers with a revolute joint each. This hand is designed for a two-position task and optimized first for dimensions and to avoid self-intersection. Then a transmission to couple the degrees of freedom is also optimized, in order to create an underactuated, pick-and-place hand able to create 5 contact points while being driven with single actuation.