This paper proposes a novel robotic hand design for assembly tasks. The idea is to combine two simple grippers -- an inner gripper which is used for precise alignment, and an outer gripper which is used for stable holding. Conventional robotic hands require complicated compliant mechanisms or complicated control strategy and force sensing to conduct assemble tasks, which makes them costly and difficult to pick and arrange small objects like screws or washers. Compared to the conventional hands, the proposed design provides a low-cost solution for aligning, picking up, and arranging various objects by taking advantages of the geometric constraints of the positioning fingers and gravity. It is able to deal with small screws and washers, and eliminate the position errors of cylindrical objects or objects with cylindrical holes. In the experiments, both real-world tasks and quantitative analysis are performed to validate the aligning, picking, and arrangements abilities of the design.
For the work with similar design goals, @cite_13 designed a gripper that can position and hold objects using a chuck clamping mechanism. The surface of their fingertips is carefully cut to generate tangential contact forces and push target objects to the hand center. @cite_8 designed a gripper that can twist and re-positioning objects by combining linear motors and rotational motors. @cite_12 presented the design of fingertips to cage, align, and firmly pick up small circular parts like bearings, washers, and gears. The design is later used in real-world assembly tasks in @cite_16 . More generally, @cite_0 proposed the design of finger shapes for 1DoF planar actuation, where he proposed a tool to transform the geometry contact constraints into an effector shape. @cite_18 used a self-locking underactuated mechanism mounted in parallel to actuators to firmly grasp objects. The self-locking is triggered automatically when the desired grasp is achieved. Without the self-locking mechanism, their hand design is similar to @cite_4 . @cite_7 proposed a gripper design with two shape adaptive mechanisms: A multi-finger mechanism to align objects and a granular jamming gripper to firmly hold objects.
@cite_18 @cite_4 @cite_7 @cite_8 @cite_0 @cite_16 @cite_13 @cite_12
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We describe the concept and first prototype of a novel mechatronic design of a robotic gripper, which aims at being mounted on a humanoid robot to achieve firm (i.e. locked) and robust grasps. Such grasps could ideally support complex multi-contact motions, such as ladder climbing, or manipulation of complex tools, with energy efficiency. For this purpose, we propose a solution by designing a smart self-locking underactuated mechanism mounted in parallel to actuators to be triggered automatically when the desired grasp is achieved. This design leverages adjustable power distribution between the gripper and the brake through a differential gear. The advantages of adaptive, firm grasping, and energy-saving capabilities of our gripper are experimentally demonstrated by a prototype gripper. This paper introduces the iRobot-Harvard-Yale (iHY) Hand, an underactuated hand driven by five actuators that is capable of performing a wide range of grasping and in-hand repositioning tasks. This hand was designed to address the need for a durable, inexpensive, moderately dexterous hand suitable for use on mobile robots. The primary focus of this paper will be on the novel simplified design of the iHY Hand, which was developed by choosing a set of target tasks around which the hand was optimized. Particular emphasis is placed on the development of underactuated fingers that are capable of both firm power grasps and low-stiffness fingertip grasps using only the compliant mechanics of the fingers. Experimental results demonstrate successful grasping of a wide range of target objects, the stability of fingertip grasping, and the ability to adjust the force exerted on grasped objects using high-impedance actuators and underactuated fingers. Many one-degree-of-freedom (1-DOF) grippers have been used in factories. This paper focuses on the design of the 1-DOF parts handling device for picking up small objects robustly and agilely and realizing assembly tasks. In our conventional research, we proposed a concept for the handling device, which cages an object without letting the object escape from its tips before closing them completely and then grasps the object robustly at a unique position of the tips. In this paper, we propose a method for designing the shape of the device's tips by considering not only the caging and self-alignment of the object but also the gear assembly task. We also develop the robust and agile pick-up device (RAPiD) with tips designed by the new method and present experimental results that illustrate the ability of RAPiD to handle and assemble gears. In this letter, we present a novel gripper, whose design was inspired by chuck clamping devices, for transferring heavy objects and assembling parts precisely in industrial applications. The developed gripper is lightweight (0.9 kg), can manipulate heavy payloads (over 23 kgf), and can automatically align its position and posture via a grasping motion. A fingertip design criterion is presented for the position alignment, while a control strategy is presented for the posture alignment. With one actuator, this gripper realized the above features. This letter describes the mathematical analyses and experiments used to validate these key metrics. In this study, we consider the development of a device for handling small parts for automatic product assembly in factories. Many robotic hands and one-degree-of-freedom grippers have been proposed as grasping parts; here, we focus on the shape of the tips of a handling device for picking up small parts robustly and agilely. In this research, we propose a concept for a handling device for picking up small round parts. In this concept, the handling device cages an object without letting the object escape from its tips before closing them completely and then grasps the object robustly at a unique position of the tips. Using this caging and self-alignment concept, the handling device can pick up objects robustly and agilely. In this paper, we focus on a method for designing the shape of the device's tips using the concept of caging and self-alignment of objects. We also develop the robust and agile pick-up device (RAPiD) with tips designed by the new method and present experimental results that illustrate the validity of the concept and the ability of RAPiD to handle small parts.