On the Optimal Design of Underactuated Fingers Using Rolling Contact Joints

The design of underactuated fingers using rolling contact joints is addressed in this article in order to increase performance in robotic and prosthetic hands applications. Rolling contact joints have proven to be a promising alternative to revolute joints by increasing the range of motion, introducing compliance and decreasing internal friction. The conditions of optimal design for fingers using such joints are however not well stated. In order to fully exploit the potential of rolling-contact-joint based fingers, their design space is extended and performance metrics adapted to underactuated fingers are used in this letter. An optimization based on these metrics is performed over the large design space using genetic algorithms to find an optimal design. The solution obtained is then used to build a prototype and its performance is compared to that predicted by the model and to a comparative design using a realistic test bench.