An Underactuated Tendon-Driven Gripper with Variable Stiffness for Deformable Agri-Food Objects

Grasping and manipulation of deformable objects are challenging problems in the food-processing industry. Food objects vary wildly in shape, size, mass, and stiffness. We present the design and control of an underactuated tendon-driven finger-based gripper with as key features high adaptability and variable joint stiffness. We first present a kinematic analysis of tendon routing in the context of grasp force and adjustable stiffness, as well as a control strategy to leverage these features. We then present a proof-of-concept prototype, which is validated in experiment. The results show that stable grasps can be achieved adaptively, and that grasp force and joint stiffness can be regulated independently for fragile objects.