A low-cost, high-strength, open-source, rapid prototypeable underactuated robot gripper

Abstract

In this work, an underactuated robot gripper was designed to meet specifications for strength, cost, and ease of manufacturing with Open-Source distribution in mind. The specifications emerged from a need for inexpensive grippers that can be used on robots that help people brace and balance. The structure and transmission of the gripper is designed to bear 150 lbs-force of static tensile and compressive loads. Gripping forces that exceed the static actuator force output are achieved by a novel method of clamping the main drive tendon by detecting dynamic overshoot and applying a self-helping cable brake, relieving the main drive actuator. The geometry, stiffness, and behavior of the gripper was designed using mathematical models and tools developed in prior art for the optimal design of underactuated hands. Apart from the actuators and waterjet machining services, the materials for the gripper can be purchased in one McMaster-Carr order. The entire structure can be cut from a single sheet of 1/16" 2024 aluminum and requires one operation on a waterjet machine, which can be found in many machine shops or through online machining services. It is the intention of the author to release the design files as Open-Source in order to allow robot researchers, engineers, and enthusiasts to use this gripper in their own work.