Technical Brief

A Rigid Mechanism With Uniform, Variable Curvature1

[+] Author and Article Information
Kaitlin Oliver Butler, Andrew L. Orekhov, Jake Childs, Caleb Rucker

Department of Mechanical, Aerospace, and
Biomedical Engineering,
University of Tennessee,
Knoxville, TN 37996-4504

DOI: 10.1115/1.4033808Manuscript received March 1, 2016; final manuscript received March 17, 2016; published online August 1, 2016. Editor: William Durfee.

J. Med. Devices 10(3), 030953 (Aug 01, 2016) (2 pages) Paper No: MED-16-1120; doi: 10.1115/1.4033808 History: Received March 01, 2016; Revised March 17, 2016

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Burgner-Kahrs, J. , Rucker, D. C. , and Choset, H. , 2015, “ Continuum Robots for Medical Applications: A Survey,” IEEE Trans. Rob., 31(6), pp. 1261–1280. [CrossRef]
Kim, Y.-J. , Cheng, S. , Kim, S. , and Iagnemma, K. , 2014, “ A Stiffness-Adjustable Hyper-Redundant Manipulator Using a Variable Neutral-Line Mechanism for Minimally Invasive Surgery,” IEEE Trans. Rob., 30(2), pp. 382–395. [CrossRef]
Webster, R. J. , and Jones, B. A. , 2010, “ Design and Kinematic Modeling of Constant Curvature Continuum Robots: A Review,” Int. J. Rob. Res., 29(13), pp. 1661–1683. [CrossRef]
Intuitive Surgical, 2015, “ EndoWrist Instruments,” Intuitive Surgical, Inc., Sunnyvale, CA, accessed Jan. 27, 2016, http://www.intuitivesurgical.com/products/instruments/


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Fig. 5

The device prototype can resist a force of 0.5 N (hanging mass of 50 g) without significant deflection in various positions

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Fig. 4

Shown with a penny as reference to scale, the prototype is 10 mm across and 22 mm deep, a size appropriate for MIS. It consists of four modules and is approximately 30 mm long.

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Fig. 3

Stacking multiple modules of the crossed four-bar mechanism and modifying them with a module-linking bar create a single-DOF, uniform curvature arm. The pictured chain is four modules long.

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Fig. 2

The chain of mechanism modules is linked by a single, module-linking bar that forms a secondary mechanism through shared bar sections with the primary mechanism, driving the synchronous motion

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Fig. 1

A crossed four-bar mechanism forms two congruent triangles when the cross bars are of equal length and the top and bottom bars are of equal length. It maintains this congruence even when the first link is rotated, and the top and bottom are no longer parallel.



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