Control-Oriented Finger Kinematic Model: Geometry-Based Approach

Abstract

This paper proposes a novel finger kinematic model for human hand configurations, which applies to the realization of a naturalistic human finger motion for robotic finger systems and artificial hands. The proposed finger model is derived based on the geometry of a hand shape grasping a virtual cylindrical object. The model is capable of describing the natural rotation configuration of the joints of a long finger with three degrees of freedom by a single parameter, i.e., the radius of a cylindrical object. Experimental validation of the model shows that it can simulate closely naturalistic human finger movements. With the use of the proposed model, discussions were made on how to achieve multifinger coordination that makes task-specific hand movements or a posture for specific hand actions. Due to the simplicity of the model to define joints angle configuration in a long finger by a single parameter, the combination of the proposed model and the multifinger coordination concept discussed can be seen as an inclusive framework in human-like hand systems design and control. This paper is the first step toward exploring future novel combined design–control strategies for the development of under-actuated prosthetic and powered orthotic devices for the naturalistic motion that are based on both Cartesian space trajectory tracking and joint angle coordination.