Kinematics of grasping and manipulation of aB-spline surface object by a multifingered robot hand

Abstract

Kinematics of grasping and manipulation by a multifingered robotic hand where multifinger surfaces are in contact with an object is solved. The surface of the object was represented by B-spline surfaces to model objects of various shapes. The fingers were modeled by cylindrical links and a half ellipsoid fingertip. Geometric contact equations have been solved for all possible contact combinations between the finger surface and the object. The simulation system calculated joint displacements and contact locations for a given trajectory of the object. Since there are no closed form solutions for contact or intersection between these surfaces, kinematics of grasping was solved by recursive numerical calculation. The initial estimate of the contact point was obtained by approximating the B-spline surface by a polyhedron. As for the simulation of manipulation, exact contact locations were updated by solving the contact equations according to the given contact conditions such as pure rolling, twist-rolling, or slide-twist-rolling. Several examples of simulation of grasping and manipulation are presented. ©1999 John Wiley & Sons, Inc.