Recognizing polygonal parts from width measurements

Automatic recognition of parts is an important problem in many industrial applications. One model of the problem is: Given a nite set of polygonal parts, use a set of \width" measurements taken by a parallel-jaw gripper to determine which part is present. We study the problem of computing e cient strategies (\grasp plans"), with the goal to minimize the number of measurements necessary in the worst case. We show that nding a minimum length grasp plan is NP-hard, and give a polynomial time approximation algorithm that is simple and produces a solution that is within a log factor from optimal.