Technical Brief

An underactuated PASA finger capable of perfectly linear motion with compensatory displacement

[+] Author and Article Information
Eric Zheng

Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China

Wenzeng Zhang

Associate Professor, Member of ASME, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China

1Corresponding author.

ASME doi:10.1115/1.4041786 History: Received September 03, 2018; Revised October 12, 2018


This paper presents a novel design for a robotic end effector. In particular, the design features a multi-fingered underactuated gripper capable of performing parallel and self-adaptive (PASA) grasping. The unique use of an eccentric cam fixed to a modified four-bar linkage mechanism allows the finger to compensate for the typical gap distance found during parallel pinching, improving the ability to grasp objects against surfaces and in tight spaces. A static analysis is performed on the design to determine the equilibrium conditions necessary for a successful grasp using this design in both the parallel and self-adaptive modes. The mechanics of a four-bar mechanism are used to determine the grasp velocity and positioning of the hand in both grasp modes. Experimental results with a finger prototype confirm the desired closing trajectory.

Copyright (c) 2018 by ASME
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