Document Type
Event
Keywords
Four-bar mechanisms, stiff-hinged mechanism, prosthetic hands, fingertips, grasp stability
Description
The purpose of this study is to analyze linkage- based prosthetic fingertips. The novel design consists of small four-bar mechanisms attached to each section of the opposing fingers replacing what would be the pulp of normal anatomical fingers. The four-bar mechanisms allow the prosthetic hand to conform to the shape of objects during grasp The goal of these prosthetic fingertips is to maximize the functionality of the hand while minimizing the number of inputs that the user has to control. This is crucial in prosthetics where the user may have limited input options, but it may also be useful in robotics.
A prosthetic hand has two functions: controlling the orientation of the artificial finger pulps and controlling their position relative to the object. We consider these two functions independently. First, we describe the small four- bar mechanisms which control the orientation of simulated pulps. The stability of the four-bar mechanisms is described as well as their advantages in contrast to a stiff- hinged single link. We then propose concepts for positioning the fingertips in two- and three-finger configurations. The focus of this paper is in the function of the four-bar fingertip mechanism; future research will address the optimal configuration of the fingertips on the hand.
The principle method used in this paper is a stability analysis via the principle of virtual work for a crossed four-bar mechanism, and, for comparison purposes, a stiff-hinged dyad. From this analysis we are able to show that four-bar fingertip mechanisms are self-stabilizing for a large range of rotation of the link on which the force is applied and a large range of directions that the force is applied. Stability is indifferent to the magnitude of the force applied to it (assuming that the force does not damage/deform the mechanism).
DOI
https://doi.org/10.5038/FRXK7696
Linkage-Based Prosthetic Fingertips: Stability Analysis
The purpose of this study is to analyze linkage- based prosthetic fingertips. The novel design consists of small four-bar mechanisms attached to each section of the opposing fingers replacing what would be the pulp of normal anatomical fingers. The four-bar mechanisms allow the prosthetic hand to conform to the shape of objects during grasp The goal of these prosthetic fingertips is to maximize the functionality of the hand while minimizing the number of inputs that the user has to control. This is crucial in prosthetics where the user may have limited input options, but it may also be useful in robotics.
A prosthetic hand has two functions: controlling the orientation of the artificial finger pulps and controlling their position relative to the object. We consider these two functions independently. First, we describe the small four- bar mechanisms which control the orientation of simulated pulps. The stability of the four-bar mechanisms is described as well as their advantages in contrast to a stiff- hinged single link. We then propose concepts for positioning the fingertips in two- and three-finger configurations. The focus of this paper is in the function of the four-bar fingertip mechanism; future research will address the optimal configuration of the fingertips on the hand.
The principle method used in this paper is a stability analysis via the principle of virtual work for a crossed four-bar mechanism, and, for comparison purposes, a stiff-hinged dyad. From this analysis we are able to show that four-bar fingertip mechanisms are self-stabilizing for a large range of rotation of the link on which the force is applied and a large range of directions that the force is applied. Stability is indifferent to the magnitude of the force applied to it (assuming that the force does not damage/deform the mechanism).