Geometry-based finger kinematic models for joint rotation configuration and parameter estimation

Jong-Seob Won,Seonhun Lee

doi:10.1177/1729881420930576

Jong-Seob Won, Seonhun Lee

Open Access

https://doi.org/10.1177/1729881420930576

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Abstract

In this work, geometry-based finger kinematic models for joint rotation configuration are proposed. The purpose of the work is to provide an effective means of describing an individual-specific finger motion during flexion or extension movements as precisely as possible. Based on the finger’s geometric postures that are observed when fingers naturally grasp a cylindrical object with a circular cross-section, its geometric relation between each phalanx of a finger and the object is extracted, and forms of contact between them are taken into consideration to secure more degrees of freedom for representing finger motions and are parameterized in the model development. A parameter identification approach is adopted to find model parameters that can be used to describe an individual-specific grasping style. For the validation of the proposed models, a set of optical motion capture experiments is performed. From the simulation study, one can see that the models provide one of the feasible and viable solutions to imitate the human finger’s flexion and/or extension movements.

Highlights

The motion of the hand that implements object manipulation or grasp is based on the function of fingers
Finger kinematic models have widely been studied in a variety of research/ industrial sectors, such as for human fingers simulation,[1] finger motion coordination,[2,3,4] virtual hand modeling and simulation,[5,6,7,8,9] articulated human hand,[10,11] prosthetics,[12] for example
Since the finger posture is determined solely on flexion or extension motions, it is required that the models should be able to provide the angular position of each joint as they make a gesture

Summary

Introduction

The motion of the hand that implements object manipulation or grasp (prehension) is based on the function of fingers. Since the finger posture is determined solely on flexion or extension motions, it is required that the models should be able to provide the angular position of each joint as they make a gesture To cope with these needs, in our recent work,[9] a geometry-based finger kinematic model is proposed. The finger kinematic models proposed in the work can be construed as a generalized version of the previous models, which are capable of providing more degrees of freedom (DOFs) to precisely describe finger’s flexion/ extension motions for an individual-specific grasping style. It is assumed in the model that during flexion/extension motions each contact takes place at a point on the line segment which is in parallel to the groove inbetween adjacent phalanges and its length is the same as the thickness of the joint (denoted by dotted circles in the figure) As mentioned earlier, this assumption can be materialized by introducing contact angles. MCP: metacarpophalangeal. aThe conic section includes a cross-section of circle, ellipse, parabola, and hyperbola

Conic section þ triangle Numerical p1

Conclusion