ABSTRACT

This paper outlines geometric and algorithmic issues common to various types of nonprehensile manipula­ tion and gives some results for planar dynamic manip­ ulation.

Nonprehensile manipulation is manipulation without a form-or force-closure grasp. Examples include push­ ing, throwing, juggling, tapping, batting, and rolling (Mason [24]; Higuchi [11]; Buhler and Koditschek [6]; Erdmann [8]; Huang et al [12]; Zumel and Erd­ mann [40]; Aiyama et al. [1]; Trinkle and Zeng [37]). In each of these examples, the robot takes advantage of the natural task dynamics to help control the mo­ tion of the part. Nonprehensile manipulation occupies the majority of the manipulation spectrum, compris­ ing everything between situations where the robot ex­ erts complete control to situations where the natural dynamics exert complete control. During a baseball throw, the ball is at first held firmly in the hand, then is allowed to roll off the fingers, and finally follows a free-flight trajectory determined by gravity and air re­ sistance. The nonprehensile manipulation problem is to arrange the rolling motion on the fingers such that the release state will allow the ball to reach the goal state.