Abstract: Inspired by the morphology of human fingers, this paper proposes an underactuated rigid-soft coupled robotic gripper whose finger is designed as the combination of a rigid skeleton and a soft tissue. Different from the current grippers who have multi-point contact or line contact with the target objects, the proposed robotic gripper enables surface contact and leads to flexible grasping and robust holding. The actuated mechanism, which is the palm of proposed gripper, is optimized for excellent operability based on a mathematical model. Soft material selection and rigid skeleton structure of fingers are then analyzed through a series of dynamic simulations by RecurDyn and Adams. After above design process including topology analysis, actuated mechanism optimization, soft material selection and rigid skeleton analysis, the rigid-soft coupled robotic gripper is fabricated via 3D printing. Finally, the grasping and holding capabilities are validated by experiments testing the stiffness of a single finger and the impact resistance of the gripper. Experimental results show that the proposed rigid-soft coupled robotic gripper can adapt to objects with different properties (shape, size, weight and softness) and hold them steadily. It confirms the feasibility of the design procedure, as well as the compliant and dexterous grasping capabilities of proposed rigid-soft coupled gripper.

Key words: Rigid-soft coupled robotic gripper , · Parameter optimization , · Dynamic simulation , · Adaptive grasping , · Robust holding