SAU-RFC hand: a novel self-adaptive underactuated robot hand with rigid-flexible coupling fingers

Abstract

In this paper, a novel self-adaptive underactuated robot hand with rigid-flexible coupling fingers (SAU-RFC hand) is proposed. The seven degrees of freedom (DOFs) SAU-RFC hand is driven by four servomotors, consists of three fingers, including two side-turning (ST) fingers and one non-side-turning finger. Specially, the ST fingers can perform synchronous reverse rotation laterally with each other. Each finger with three joints and two DOFs introduces a flexible structure, and the inner part of the proximal phalanx that makes most of the contact with the object is replaced by a flexible belt. The fingers can generate flexion/extension under the pull of the flexible belt, and the middle and distal phalanxes are mechanically coupled through a four-bar linkage. In particular, the flexible belt in the inner direction of the finger will deform, while it will not deform in the outer direction since the outer is a rigid structure. The flexible belt not only plays the role of transmitting power but also has the effect of uniformizing the contact force. Due to the rigid-flexible finger structure, the developed robot hand has a higher self-adaptive grasping ability for objects with different shapes, sizes, and hardness. In addition, the kinematic and kinetic analyses of SAU-RFC hand are performed. A contact force distribution model is established for the flexible belt, which demonstrates its effect of promoting uniform force distribution theoretically. In the end, experiments are conducted on different objects to verify the performance of SAU-RFC hand.

A one-DOF compliant gripper mechanism with four identical twofold-symmetric Bricard linkages

“…Compared with the existing grippers that can grasp objects with complex shapes, such as five-fingered humanoid robotic hand [7], underactuated robotic hand [18], SAU-RFC hand [19], etc., the compliant gripper proposed in this paper has the advantages of compact structure, single degree of freedom and low manufacturing cost, and owns lower stiffness due to the usage of compliant joints.…”

“…Hota and Kumar [18] present a study on the effect of design parameters of an underactuated hand on its grasp performance. Su et al [19] proposed a novel self-adaptive underactuated robot hand with rigid-flexible coupling fingers. Furthermore, Marwan et al [20] presented a comprehensive review devoted to the techniques related to reaching and grasping objects in different workplaces.…”

Anthropomorphic Soft Hand: Dexterity, Sensing, and Machine Learning

“…This is primarily attributed to the limited dexterity of soft actuators, which typically function as the fingers in soft hands. Most soft actuators have pre-defined motion trajectories, resulting in fixed trajectories for the fingers and overlapping motion limited to a singular point [72][73][74]. This paradox has spurred research into specific operational processes and the design of more dexterous hands, which are intelligent, multipurpose mechanical structures designed for a variety of tasks [4,6,20,75].…”

Special issue on recent advances in field and service robotics: handling harsh environments and cooperation

“…To improve the grasping capacity of robots, a new self-adaptive underactuated robot hand with rigidflexible coupling fingers is designed, as reported in Su, Wang et al [6]. The robotic hand, driven by four servomotors, consists of three fingers with seven degrees of freedom.…”