Each manipulation defines a basic translation or rotation of an object with either circular or rectangular cross section and can be performed with a number of different grasp configurations. Taken together, the set of primitives enables the hand to rotate or translate objects in any direction in an object-centered frame. Defining basic strategies, an analog to motor control programs, simplifies the planning requirements of a robot system. Once a high-level planner has decided that a particular object motion is required, the action is performed autonomously. Manipulations are parametrized to cope with different task requirements, including grasp force, motion distance, and speed.
Trajectories define the finger contact motions during manipulation.
A hand's workspace is generally complex and does not admit a closed-form solution. For object manipulation, allowable fingertip trajectories for all contacts must be found simultaneously. A configuration-space analysis is performed that yields the maximum object motion distance for given sized objects, as well as the initial grasping positions and wrist positions in a global frame. This information is required to position the robot arm for maximum object manipulability, that is, to move it during the reach phase of a manipulation. References Paul Michelman and Peter Allen.