Design Innovation Paper

Design and Testing of a Highly Reconfigurable Fixture With Lockable Robotic Arms

[+] Author and Article Information
Shengnan Lu

Robotics Institute,
Beihang University,
Beijing 100191, China;
PMAR Robotics,
University of Genoa,
Genoa 16145, Italy
e-mail: lvshengnan5@gmail.com

Zeshan Ahmad

PMAR Robotics,
University of Genoa,
Genoa 16145, Italy
e-mail: zeshan@dimec.unige.it

Matteo Zoppi

PMAR Robotics,
University of Genoa,
Genoa 16145, Italy
e-mail: zoppi@dimec.unige.it

Xilun Ding

Robotics Institute,
Beihang University,
Beijing 100191, China
e-mail: xlding@buaa.edu.cn

Dimiter Zlatanov

PMAR Robotics,
University of Genoa,
Genoa 16145, Italy
e-mail: zlatanov@dimec.unige.it

Rezia Molfino

PMAR Robotics,
University of Genoa,
Genoa 16145, Italy
e-mail: molfino@dimec.unige.it

Contributed by the Design Innovation and Devices of ASME for publication in the JOURNAL OF MECHANICAL DESIGN. Manuscript received June 13, 2015; final manuscript received February 23, 2016; published online June 16, 2016. Assoc. Editor: David Myszka.

J. Mech. Des 138(8), 085001 (Jun 16, 2016) (8 pages) Paper No: MD-15-1418; doi: 10.1115/1.4033037 History: Received June 13, 2015; Revised February 23, 2016

The paper describes an innovative fixture created within the AUTORECON project of the European Commission's 7th Framework Program. The fixture is designed to respond to the automotive industry's needs of high modularity and full flexibility, by allowing the secure multishape grasping of a very wide range of (often large and heavy) metal workpieces typical for car-assembly operations. The fixture is used as an end-effector of an industrial robot, which in turn acts in cooperation with other machines, such as other robots performing machining or other processes on the part. The fixturing device is both a highly reconfigurable structure and a robotic mechanism: moving as a programmable robot to reconfigure and acting as a supporting structure once a hold on the part has been established. This dual functioning has been made possible by the development of a key component, a stepless lockable revolute joint, described herein. In order to get a readily modifiable system, all parts of the fixture are designed as modules. Prototypes of the main parts and the whole fixture have been fabricated and experiments validating the design are reported.

Copyright © 2016 by ASME
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Fig. 1

The new fixture acting as the gripper of an industrial robot

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Fig. 2

Working procedure of the reconfigurable fixture

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Fig. 3

Concept A: A lockable joint design using a cone collet

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Fig. 4

Mechanical principle of concept B

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Fig. 5

Concept C: A lockable joint with a hydraulic clamping sleeve

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Fig. 6

Structure of the lockable joint

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Fig. 7

Schematic of the driving system

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Fig. 8

Design of the lockable joint

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Fig. 9

Structure of the arm: (a) upper arm and (b) forearm

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Fig. 10

(a) Static analysis of the forearm. (b) The arm prototype.

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Fig. 11

Structure of the reconfigurable fixture

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Fig. 12

Reconfigurable fixture prototype

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Fig. 13

Testing of the 800 N·m lockable joint

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Fig. 14

Experimental setup for stiffness measurement

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Fig. 15

Same force applied in different configurations: (a) α = 120 deg, (b) α = 90 deg, and (c) α = 70 deg

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Fig. 16

Forces applied along different lines: (a) along the rotating axis of the end-effector, (b) perpendicular to the forearm, and (c) along the forearm

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Fig. 17

Grasping of workpieces



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