A guideline for specifying compliance in multi-fingered operations

Abstract

In this paper, we present a fundamental compliance analysis for multi-fingered hands and also provide a guideline for specifying compliance characteristics in the three-dimensional operational space of multi-fingered hands. Through the analysis of the stiffness relation between the operational space and the fingertip space of multi-fingered hands, it is shown that some of the coupling stiffness elements cannot be planned arbitrarily. Also, an independent finger-based compliance control method to achieve the given compliance characteristics is described. Conclusively, when we specify the operational stiffness matrix, the contents of the operational stiffness matrix cannot be fully achieved by influence of the grasp geometry of multi-fingered hands. The grasp positions of fingers as well as the RCC point, which are shown important factors, should be chosen to achieve the specified operational stiffness matrix for the given task. The cases of a point contact with friction and soft contact are examined as illustrative examples. It is observed that a five-fingered robotic hand is sufficient for implementation of proper three-dimensional compliance characteristics. (C) 2004 Wiley Periodicals, Inc.