Is a Vertex at C Stable Grasping with a Multi- Fingered Robot Hand: a Behavior-based Ameter: Strategies for Recognizing Polygo- 3.2.1 Improving Accuracy 3.2 First Algorithm Reactive Algorithms for Grasping Using a Modiied Parallel Jaw Gripper

A or C B. We want to avoid having a vertex at both. In such a case, we are stuck at a local maximum, and we escape by performing a small rotation in the same direction as the previous rotation. If these additional beams are available, then the algorithm can be made entirely table driven. In fact, by moving this beam slightly further from its jaw, we can eliminate cases when there is a vertex on each side such that the line joining them is almost orthogonal to the jaws. This situation corresponds to low stability grasps. We can simulate beam 5 using either beam 1 or 2, and repositioning the gripper, assuming we have precise measurement data for the current gripper width. For this algorithm we also need to assume that there are no two edges forming a very small angle. Also it seems that this algorithm cannot be generalized to objects with rounded boundaries, since it depends on the presence of vertices. 5 Conclusion We have presented simple algorithms for nding a grasp of a thick planar object using a modiied parallel jaw gripper. These modiications are simple and obviate the need for complex vision systems. This is one of the rst attempts at producing robot manipula-tors that know how to grasp by themselves, feeling the object rst, but only suuciently in order to grasp it. We are currently in the process of constructing such a gripper, and we expect the algorithms to perform very smoothly, since the motions involved between steps will be very small. 6 Algorithm 2 State A 3 A 4 B 4 B 3 Action 0. .. . close the gripper 1 x. .. translate left and up 2. x. . translate right and up 3. . x. translate left and down 4. .. x translate right and down 5 x x. . translate up 6. . x x translate down 7 x. . x rotate clockwise 8. x x. rotate counter{clockwise 9 x. x. translate left 10. x. x translate right 11 x x. x translate parallel A 4 to right 12 x x x. translate parallel A 3 to left 13 x. x x translate parallel B 3 to right 14. x x x translate parallel B 4 to left 15 x x x x check if done (see text) 3.3 Competitiveness analysis Ideally, we would like to compare this algorithm with …