Sub-Optimal Algorithms for Force Distribution in Multifingered Grippers

The work described in this paper addresses the problem of determination of the appropriate distribution of forces between the fingers of a multifingered gripper grasping an object. The system is statically indeterminate and an optimal solution for this problem is desired for force control. A fast and efficient sub-optimal method for computing the grasping forces is presented. This method is based on the superposition of finger-interaction forces on equilibrating forces. An interaction force is defined as the component of the vector difference of the finger contact forces at any two fingers along the line joining the two contact points. They are computed based on the assumption that the normals at the point of contact pass through the centroid of the contact points and are therefore independent of the actual geometry of the object. The contact interaction is modelled as a point contact. The problems associated with making the algorithm independent of the object geometry are explored.