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. 2022 Aug:7:V007T07A047.
doi: 10.1115/detc2022-89625. Epub 2022 Nov 11.

DESIGN, ANALYSIS, AND PROTOTYPING OF A NOVEL SINGLE DEGREE-OF-FREEDOM INDEX FINGER EXOSKELETON MECHANISM

Wenda Xu  1 , Yujiong Liu  1 , Pinhas Ben-Tzvi  1
Affiliations

DESIGN, ANALYSIS, AND PROTOTYPING OF A NOVEL SINGLE DEGREE-OF-FREEDOM INDEX FINGER EXOSKELETON MECHANISM

Wenda Xu et al. Proc ASME Des Eng Tech Conf. 2022 Aug.

Abstract

This paper presents a novel index finger exoskeleton mechanism for patients who suffer from brachial plexus injuries, which takes advantage of our previously proposed rigid coupling hybrid mechanism (RCHM) concept used for robotic tail mechanisms. The core idea of this concept is to drive the (i+1)-th link using the motions of the i-th link, instead of the traditional way of transmitting motion directly from the base. This specific configuration allows designing a single degree of freedom (DOF) bending mechanism using a low-profile rack and pinion mechanism and makes the proposed exoskeleton system compact, lightweight, and portable, which are highly desired features for daily usages of exoskeleton gloves. The mechanism is optimized to mimic the grasping motions of human fingers and the sensitivity analysis of its critical design variables is then conducted to explore the performance of the optimization results. The results show that for the current design, the tip position accuracy is mainly affected by the distance between the rack and the corresponding joints. A proof-of-concept prototype was built to verify the novel mobility of the proposed mechanism and to evaluate its performance on a human finger. The index finger exoskeleton experiments demonstrate the new mechanism's ability to grasp small objects.

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Figures

Figure 1.
Figure 1.
Overview of the index finger exoskeleton
Figure 2.
Figure 2.
Example for 1 DOF of RCHMS and motion transmission between connected linkages.
Figure 3.
Figure 3.
Full view of bent index exoskeleton finger and kinematic model of the PIP joint
Figure 4.
Figure 4.
Comparison between index finger motion and index exoskeleton trajectory, and bending angles of the joints.
Figure 5.
Figure 5.
Sensitivity analysis of each design variable. The Red lines refer to the sensitivity for the x component of p and the blue lines refer to the y component.
Figure 6.
Figure 6.
Motion experiments with the index exoskeleton finger. (A) Side view of the initial position. (B) Side view of the position during the motion. (C) Side view at the end of the motion
See this image and copyright information in PMC

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