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Research Papers

Coupled and Self-Adaptive Under-Actuated Finger With a Novel S-Coupled and Secondly Self-Adaptive Mechanism

[+] Author and Article Information
Guoxuan Li

Department of Mechanical Engineering,
Tsinghua University,
Beijing 100084, China
e-mail: ligx11@mails.tsinghua.edu.cn

Chi Zhang

Department of Mechanical Engineering,
Northwestern University,
Evanston, IL 60208
e-mail: chizhang2015@u.northwestern.edu

Wenzeng Zhang

Department of Mechanical Engineering,
Tsinghua University,
Beijing 100084, China
e-mail: wenzeng@tsinghua.edu.cn

Zhenguo Sun

Department of Mechanical Engineering,
Tsinghua University,
Beijing 100084, China
e-mail: sunzhg@tsinghua.edu.cn

Qiang Chen

Department of Mechanical Engineering,
Tsinghua University,
Beijing 100084, China
e-mail: chenq@tsinghua.edu.cn

1Corresponding author.

Contributed by the Mechanisms and Robotics Committee of ASME for publication in the JOURNAL OF MECHANISMS AND ROBOTICS. Manuscript received October 21, 2013; final manuscript received April 15, 2014; published online June 17, 2014. Assoc. Editor: Pierre M. Larochelle.

J. Mechanisms Robotics 6(4), 041010 (Jun 17, 2014) (10 pages) Paper No: JMR-13-1215; doi: 10.1115/1.4027704 History: Received October 21, 2013; Revised April 15, 2014

This paper presents a novel under-actuated (UA) finger with first coupled and secondly self-adaptive (COSA) grasping mode. COSA fingers can adaptively grasp objects with different sizes and shapes while its motions during grasping are anthropopathic. Until now there are two COSA mechanisms available and they are both direct parallel combinations of coupled mechanism and self-adaptive mechanism. These kind of direct combinations lead to complex mechanical structure and high power consumption. This paper proposes a novel single-route transmission mechanism for COSA grasping mode, S-coupled and directly self-adaptive (CDSA) mechanism for short. Compared with available COSA mechanisms, the S-CDSA mechanism has simpler structure and higher grasping force. Design of 2-joint S-CDSA finger is introduced in this paper. Force analysis for 2-joint S-CDSA finger is given. Furthermore, a 2-joint S-CDSA finger is manufactured. The force analysis and experimental results show that the novel S-CDSA mechanism is effective.

Copyright © 2014 by ASME
Topics: Grasping
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References

Figures

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Fig. 1

Grasping process of COSA mode

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Fig. 2

Classification of COSA fingers

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Fig. 3

Schematic diagram of a double-route CDSA mechanism: (1) the proximal shaft; (2) the distal shaft; (3) the first active pulley; (4) the first belt; (5) the first passive pulley; (6) the second active pulley; (7) the second belt; (8) the second passive pulley; (9) the first spring; (10) the second spring; (11) the third spring; (A) coupled mechanism; (B) directly self-adaptive mechanism. When pulley 3 and pulley 6 rotate in the same direction, after the transmissions of (A) and (B), the pulley 5 and pulley 8 will rotate in different directions. Springs are applied here to coordinate the movements of (A) and (B).

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Fig. 4

Schematic diagram of S-CDSA mechanism: (1) motor; (2) base; (4) the first gear; (6) the second gear; (7) the base shaft; (8) the third gear; (9) the fourth gear; (10) the first pulley; (11) the proximal shaft; (12) the spring; (13) the proximal phalange; (14) the belt; (15) the second pulley; (16) the distal shaft; (17) the distal phalange

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Fig. 5

Mechanism of the 2-joint S-COSA finger: (1) DC motor; (2) base; (3) main-shaft gear; (4) the 1st gear; (5) crown gear; (6) the 2nd gear; (7) base shaft; (8) the 3rd gear; (9) the 4th gear; (10) driving pulley; (11) proximal shaft; (12) torsional spring; (13) proximal phalange; (14) belt; (15) driven pulley; (16) remote shaft; (17) distal phalange

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Fig. 6

Grasping process of the 2-joint S-CDSA finger: (2) base; (4) the first gear; (6) the second gear; (7) the base shaft; (8) the third gear; (9) the fourth gear; (10) the first pulley; (11) the proximal shaft; (12) torsional spring; (13) the proximal phalange; (14) belt; (15) the second pulley; (16) the distal shaft; (17) the distal phalange; (18) object

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Fig. 14

Force analysis of the unfinished grasping state

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Fig. 13

Force analysis of the finger-tip grasping state

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Fig. 12

Relationships among f1, f2, and TM when TM ranges from 0 Nmm to 800 Nmm, θ1 remains 70 deg and θ2 remains 20 deg

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Fig. 11

Relationships among f1, f2, θ1, and θ2 when TM = 700 Nmm and k = 15Nmm/deg

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Fig. 10

Relationships among f1, f2, θ1, and θ2 when TM = 300 Nmm and k = 15 N·mm/deg

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Fig. 9

Relationships among f2, θ1, and θ2 when TM = 600 Nmm and k = 15 Nmm/deg

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Fig. 8

Relationships among f1, θ1, and θ2 when TM = 600 Nmm and k = 15 Nmm/deg

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Fig. 7

Force analysis of entire grasping state

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Fig. 15

Appearance of the 2-joint S-CDSA finger and S-CDSA mechanism

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Fig. 16

Coupled grasping process of the 2-joint S-COSA finger

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Fig. 17

CDSA grasping process

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Fig. 18

Grasping states of the 2-joint S-COSA finger

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