Optimal Design of Linkage-Driven Underactuated Hand for Precise Pinching and Powerful Grasping

Pinching and grasping are the key fundamental actions for manipulator to handle objects, while achieving high-quality execution of these actions has always been an intense attention in robotics field. In this letter, a novel underactuated manipulator with composed multiple-linkage mechanism is proposed, which enables both precise pinching and powerful grasping. To eliminate trajectory errors of linear pinching, the linkage mechanism is optimized by genetic algorithm based on modelling and kinematic analysis of the finger. The optimized configuration results in a vertical displacement error less than 0.3 mm and a linear deviation less than 1%. Furthermore, the envelope linkage mechanism is optimized by taking the uniformity of force distribution, which is chosen as a performance indicator. Additionally, a rotary mechanism is installed at the proximal interphalangeal of the finger to enable the manipulator to switch different grasping modes for various types of objects. Finally, the experiments on pinching small and thin objects and grasping objects with pose-varied mode demonstrated that the developed manipulator is capable of both precise pinching and powerful grasping. This work offers a promising solution for the robotic manipulator to perform multi-type object grasping tasks.