Analysis and Implementation of Robust Grasping Behaviors

Abstract : This thesis addresses the problem of developing automatic grasping capabilities for robotic hands. Using a 2-jointed and a 4-jointed model of the hand, we establish the geometric conditions necessary for achieving form closure grasps of cylindrical objects. We then define and show how to construct the grasping pre-image for quasi-static (friction dominated) and zero-G (inertia dominated) motions for sensorless and sensor-driven grasps with and without arm motions. The grasping pre-image is the area within which the object to be grasped must lie in order to be grasped successfully. The size and shape of this area depends upon the hand and object geometry and can be increased by employing sensor triggered actions (behaviors). while the approach does not rely on detailed modeling, it is computationally inexpensive, reliable, and easy to implement. Example behaviors were successfully implemented on the Salisbury hand and on a planar 2-fingered, 4 degree-of-freedom hand.