Single-Fingered Reconfigurable Robotic Gripper With a Folding Mechanism for Narrow Working Spaces

Abstract

This paper proposes a novel single-fingered reconfigurable robotic gripper for grasping objects in narrow working spaces. The finger of the developed gripper realizes two configurations, namely, the insertion and grasping modes, using only a single motor. In the insertion mode, the finger assumes a thin shape such that it can insert its tip into a narrow space. The grasping mode of the finger is activated through a folding mechanism. Mode switching can be achieved in two ways: switching the mode actively by a motor, or combining passive rotation of the fingertip through contact with the support surface and active motorized construction of the claw. The latter approach is effective when it is unclear how much finger insertion is required for a specific task. The structure provides a simple control scheme. The performance of the proposed robotic gripper design and control methodology was experimentally evaluated. The minimum width of the insertion space required to grasp an object is 4 mm (1 mm, when using a strategy).

Single-Motor Robotic Gripper With Three Functional Modes for Grasping in Confined Spaces

“…A thin structure is also necessary for the grippers to be inserted into confined spaces. Several studies have developed robotic grippers with thin structures [4]- [11]. In the case of extremely confined spaces where the operation range of a manipulator with a gripper is limited, the changing position and posture of grasped objects should be performed in-hand to avoid collisions between the grasped objects and obstacles.…”

“…Accordingly, 𝜏𝜏 𝑑𝑑𝑟𝑟2 increases. Because 𝑓𝑓 𝑡𝑡𝑡𝑡𝑡𝑡 = 0 in this state, condition (11) for the translation of sprocket 1 is rewritten as 15) and ( 18) are satisfied, sprocket 1 is translated without relative rotation between sprocket 2 and the fingertip unit. Thus, the grasping mode is activated after the finger-bending mode.…”

“…The SMS mechanisms reduce the number of motors, resulting in a compact gripper design with thin fingers (the width of the finger was 40 mm in the initial state). The installation of SMS mechanism B enlarged the finger compared to the simple thin fingers used in, e.g., [4]- [11], which is disadvantageous for inserting the fingers into extremely narrow spaces. Finger downsizing could be achieved by using smallscaled parts.…”