Mitigate Inertia for Wrist and Forearm Towards Safe Interaction in 5-DOF Cable-Driven Robot Arm

Abstract

Demand of a lightweight robot arm for dexterously handling objects or working with low inertia has become a new challenge in robotics. This paper comes up with a novel design of a low-inertia robot arm comprising of 5 degrees of freedom (DOF) with 2 DOF at the wrist, 1 DOF at the elbow, 1 DOF at the shoulder, and 1 DOF at the base. The wrist is driven by a cable system, concurrently, all five motors actuating the robot arm locate near a shoulder center with a counterbalanced design. A novel design of a decoupling mechanism without spring components was proposed to enhance the stability of the wrist during loading heavy load. Experimental outcomes showed that our robot arm can lift 5 kg hooked at a long arm, and the accuracy in operating for the arm and the wrist reached smaller than 1 mm. This design is expected to generate a low-inertia robot arm for safe interactions and mobile applications. Our design targets to reduce the payload ratio to 1:1 with the arm weight being 5 kg and the lifetime durability of at least 6 months.