Precision object manipulation with a multifingered robot hand

This paper outlines several key issues associated with precision manipulation for robot hands. Precision manipulation is defined as the control of a grasped object using fingertip contacts alone. A set of primitive manipulation functions is defined. They are generalizable in the sense that they take parameters for different object geometry, speed, and direction of motion. A single manipulation can be performed with a number of different grasp topologies. With each manipulation there are several associated computations: 1) the trajectories of the contact points can be calculated a priori from knowledge of the desired object motion; 2) a workspace analysis is performed to determine that the manipulation is within the workspaces of all of the fingers simultaneously; and 3) task partitioning is performed to specify force- and position-controlled directions of the contact points. This partitioning controls the grasping forces on the object during the grasping and manipulation phases. The paper also describes how the primitive manipulations can be combined into complex tasks. The complex example of removing a top from a childproof bottle is presented. The manipulations were implemented on a Utah/MIT dextrous robot-hand system.