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Proceedings Paper

Development of a physical model of the human elbow joint using polyacrylonitrile fibers
Author(s): Roger V. Gonzalez; Jeffrey L. Thielman
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Paper Abstract

A physical model of the human elbow joint was designed using the polymer fiber polyacrylonitrile (PAN), developed at the University of New Mexico. The elbow model uses six PAN fiber bundles, as artificial muscles, to create the forces needed for elbow movement. These six fiber bundles were designed to imitate the major muscles that cross the human elbow joint. Four distinct movement tasks (elbow flexion/extension and forearm pronation/supination) were designed into the physical mode. Several steps were taken to meet this objective. First, the mechanical properties of the PAN fibers were characterized using the techniques developed by A. V. Hill, and compared with his results. The results show that the fiber mechanical properties have similarities to human muscle properties, and thus permitting a realistic elbow model to be developed. Second, a method of encasing the individual bundles of fibers was developed. The encasing lengthens and shortens with the fibers, prevents fluid leakage, and does not deteriorate given the acid and base fluid components. Third, a method of supplying and removing the activating fluids was developed. This system is chemically resistant, provides a method for controlling inlet and exit fluid flow, and allows for complete fluid exchange in less than 5 seconds. Finally, a microcontroller was incorporated to provide joint position and velocity control based on joint potentiometers and provide real-time feedback of joint positions. Using these components, a human elbow joint system was developed that allows movement in two degrees of freedom. Due to the characteristics of the PAN fiber bundles, the elbow joint was slower and weaker than originally designed. System improvements relate closely to increasing fiber bundle force and decreasing the reaction time constant.

Paper Details

Date Published: 20 July 1998
PDF: 7 pages
Proc. SPIE 3324, Smart Structures and Materials 1998: Smart Materials Technologies, (20 July 1998); doi: 10.1117/12.316861
Show Author Affiliations
Roger V. Gonzalez, LeTourneau Univ. (United States)
Jeffrey L. Thielman, LeTourneau Univ. and Hewlett-Packard Co. (United States)


Published in SPIE Proceedings Vol. 3324:
Smart Structures and Materials 1998: Smart Materials Technologies
Manfred R. Wuttig, Editor(s)

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