Grasping control of rolling manipulations with deformable fingertips

This paper deals with the problem of stable grasping in rolling manipulations with soft deformable fingertips in two-dimensional space and without the effect of gravity. Two rolling distance models for the soft-area contact motion and their effect on contact kinematics are considered. The modeling of contact forces in soft-area contacts is discussed and an analysis of a stable grasp is made. A simple feedback controller for stabilizing the grasp is proposed and tested in simulation. The control law is based on the object´s equilibrium conditions and is designed so that it drives the system at rest by achieving a desired value for the normal contact forces and appropriate tangential forces to balance the moments created by the contact offset.