| This dissertation addresses some of the fundamental issues in multifingered cooperative manipulation. The problems investigated were stimulated by the need to devise a motion and force allocation planner for the four fingered DIGITS system.;In motion planning, the emphasis has been on determining finger trajectories that generate smooth object motion in free space. A screw motion has been prescribed to be followed between two configurations of the object, in order to obtain simultaneous rotary and translatory motion. The effect of the joint motion limits on the path following capability of the fingers has been analyzed. It has been shown that knowledge of the direction of the surface normal at the contact point, coupled with the use of a spherical fingertip can be used to circumvent some contact uncertainty problems.;The geometry of the force system in the multi-point contact situation has been investigated using screw theory. Conditions for which the system is underspecified have been identified. An efficient solution to the minimum norm solution, the equilibrating forces, has been presented. It has been shown that the pairs of equal and opposite forces acting along the lines joining points of contact can be used to span the space of the homogeneous solutions of the underconstrained problem.;Techniques to selectively superpose the interaction forces to orient the net contact forces in desired directions have been developed. This leads to the development of a closed form solution to the optimum grasp problem in three dimensions. It has been shown that the local minimum of the maximum friction angle is characterized by a polynomial which can be symbolically enumerated. Solutions to the minimum friction angle problem can be obtained from the roots of the polynomial.;The DIGITS system is instrumented to obtain six axis contact force data from the fingertip. Efficient, stable closed form algorithms have been developed to compute the location of the contact point based on the six axis force data for cylindrical and spherical fingertip geometry. It has been shown that for fingertip surfaces made of piecewise ellipsoids, as opposed to a single ellipsoid, the solution may be non-unique. The conditions for such non-uniqueness to occur have been identified.;A simulation of the DIGITS system was implemented on a Symbolics 3650 running Genera 7.2. The modelling package, SuperSketch is used to generate the modelling primitives and rendering. |
