Citation: Han, S.; Choi, M-S.; Shin,
Y-W.; Jang, G-R.; Lee, D-H.; Cho, J.;
Park, J-H.; Bae, J-H. Screwdriving
Gripper That Mimics Human
Two-Handed Assembly Tasks.
Robotics 2022, 11, 18. https://
doi.org/10.3390/robotics11010018
Academic Editors: Yuansong Qiao
and Seamus Gordon
Received: 31 December 2021
Accepted: 25 January 2022
Published: 27 January 2022
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Article
Screwdriving Gripper That Mimics Human Two-Handed
Assembly Tasks
Sangchul Han
†
, Myoung-Su Choi
†
, Yong-Woo Shin , Ga-Ram Jang, Dong-Hyuk Lee , Jungsan Cho,
Jae-Han Park and Ji-Hun Bae *
Robotics R&D Department, Korea Institute of Industrial Technology, Ansan 15588, Korea;
bomber21@kitech.re.kr (S.H.); choims@kitech.re.kr (M.-S.C.); syw10@kitech.re.kr (Y.-W.S.);
river.j@kitech.re.kr (G.-R.J.); donghyuk@kitech.re.kr (D.-H.L.); chojs@kitech.re.kr (J.C.);
hans1024@kitech.re.kr (J.-H.P.)
* Correspondence: joseph@kitech.re.kr
† These authors contributed equally to this work.
Abstract:
Conventional assembly methods using robots need to change end-effectors or operate two
robot arms for assembly. In this study, we propose a screwdriving gripper that can perform the tasks
required for the assembly using a single robot arm. The proposed screwdriving gripper mimics a
human-two-handed operation and has three features: (1) it performs pick-and-place, peg-in-hole, and
screwdriving tasks required for assembly with a single gripper; (2) it uses a flexible link that complies
with the contact force in the environment; and (3) it employs the same joints as the pronation and
supination of the wrist, which help the manipulator to create a path. We propose a new gripper
with 3 fingers and 12 degrees of freedom to implement these features; this gripper is composed of
grasping and screwdriving parts. The grasping part has two fingers with a roll-yaw-pitch-pitch joint
configuration. Its pitch joint implements wrist pronation and supination. The screwdriving part
includes one finger with a roll-pitch-pitch joint configuration and a flexible link that can comply with
the environment; this facilitates compliance based on the direction of the external force. The end of
the screwdriving finger has a motor with a hex key attached, and an insert tip is attached to the back
of the motor. A prototype of the proposed screwdriving gripper is manufactured, and a strategy for
assembly using a prototype is proposed. The features of the proposed gripper are verified through
screwdriving task experiments using a cooperative robotic arm. The experiments showed that the
screwdriving gripper can perform tasks required for the assembly such as pick and place, peg-in-hole,
and screwdriving.
Keywords: gripper; assembly task; screwdriving; assembly robot
1. Introduction
Automation in conventional mass production processes can be achieved by dividing
tasks and applying specialized robots to each task. This method was the only practical one
when the capabilities of the robot were limited. However, with improvements in the ability
of the robot, methods that can increase the efficiency of work by performing multiple tasks
together with a single robot are being devised. Cell production, in which a small number of
workers perform multiple tasks simultaneously in the same space, is an example of such a
method. Further, cell production is effective for different types of small batch productions;
cell production using a robot is expected to help automate tasks that are currently difficult
to automate owing to economic limitations.
Furniture assembly is a representative example of such tasks, and it includes various
elements of general assembly tasks such as pick-and-place, peg-in-hole, and screwdriv-
ing tasks. It is considerably inefficient to automate such assembly tasks using multiple
specialized robots for each task; thus, research on this topic is in the nascent stages.
Knepper et al. [
1
] presented a mobile-platform-type multirobot system (IKEAbot) and
a new type of gripper for furniture assembly involving the assembly of brittle and small
Robotics 2022, 11, 18. https://doi.org/10.3390/robotics11010018 https://www.mdpi.com/journal/robotics
