Kinematic design of a planar and spherical mechanism for the abduction of the fingers of an anthropomorphic robotic Hand

This paper presents the kinematic design of an abduction mechanism for the fingers of an anthropomorphic robotic hand. This mechanism enhances the range of feasible grasps of the underactuated hand without significantly increasing its complexity. Two architectures are investigated: one is purely planar while the other uses a spherical mechanism in conjunction with a planar linkage. The analysis of the planar mechanism between the index finger and the third finger is first assessed, in which the parameters are determined in order to satisfy the constraints on the motion ranges while minimizing the coordination error. Then, the study of the mechanism joining the third finger and the little finger is summarized, followed by the analysis of the spherical mechanism. Finally, prototypes of the fingers' abduction systems using the two proposed architectures are presented.