Research Papers

A Genderless Coupling Mechanism With Six-Degrees-of-Freedom Misalignment Capability for Modular Self-Reconfigurable Robots

[+] Author and Article Information
Wael Saab

Robotics and Mechatronics Laboratory,
Department of Mechanical Engineering,
Virginia Tech,
Randolph Hall, Room 8,
460 Old Turner Street,
Blacksburg, VA 24061
e-mail: waelsaab@vt.edu

Pinhas Ben-Tzvi

Robotics and Mechatronics Laboratory,
Department of Mechanical Engineering,
Virginia Tech,
Goodwin Hall, Room 465,
635 Prices Fork Road,
Blacksburg, VA 24061
e-mail: bentzvi@vt.edu

Manuscript received December 9, 2015; final manuscript received June 6, 2016; published online September 9, 2016. Assoc. Editor: Satyandra K. Gupta.

J. Mechanisms Robotics 8(6), 061014 (Sep 09, 2016) (9 pages) Paper No: JMR-15-1335; doi: 10.1115/1.4034014 History: Received December 09, 2015; Revised June 06, 2016

This paper presents the design and integration of a genderless coupling mechanism for modular self-reconfigurable mobile robots. Modular self-reconfigurable mobile robotic systems consist of a number of self-sufficient modules that interconnect via coupling mechanisms and adopt different configurations to modify locomotion and/or manipulation capabilities. Coupling mechanisms are a critical element of these robotic systems. This paper focuses on a docking mechanism called GHEFT: a Genderless, High-strength, Efficient, Fail-safe, and high misalignment Tolerant coupling mechanism that aids self-reconfiguration. GHEFT provides a high strength and energy efficient connection using nonback drivable actuation with optimized clamping profiles that tolerate translational and angular misalignments. It also enables engagement/disengagement without gender restrictions in the presence of one-sided malfunction. The detailed design of the proposed mechanism is presented, including optimization of the clamping profile geometries. Experimental validation of misalignment tolerances and achievable clamping forces and torques is performed to demonstrate the strength, efficiency, and fail-safe capabilities of the proposed mechanism, and these results are compared to reported results of some of the existing coupling mechanisms.

Copyright © 2016 by ASME
Topics: Robots , Design , Torque , Simulation
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Fig. 1

Schematic diagram of GHEFT

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Fig. 2

(a) Isometric view of clamping profiles. (b) Side view of two docked coupling mechanisms.

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Fig. 3

(a) Serial configuration of N + 1 modular STORM robots with integrated GHEFT mechanisms. (b) Close-up view of integrated GHEFT mechanism.

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Fig. 4

Free body diagram of engaged coupling mechanisms split at the contact point between the cam and its followers

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Fig. 5

Constant lead cam groove profile and parameters

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Fig. 6

6DOF misalignment tolerance experiments: (a) along X, (b) along Y, (c) along Z, (d) about Roll β, (e) about Pitch γ, (f) about Yaw α

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Fig. 7

(a) H-grooved clamping profiles showing peaks, local minima/maxima and concave surfaces, (b) side view of engaging clamping profiles misaligned in X-direction, (c) design parameters of clamping profiles in fully open configuration

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Fig. 8

(a) Dynamic simulation showing x-axis misalignment test. (b) Simulation results of the docked configuration.

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Fig. 11

Energy required to establish and maintain a connection for varied loading conditions acting on the clamping profiles

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Fig. 10

Relationship between measured clamping force, relative rotational torque, and percent actuation torque

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Fig. 9

Assembled prototype of GHEFT. (a) Front isometric view. (b) Back Isometric.




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