As every real mechanical hand has a limited accuracy, the grasp planning process must be prepared to cope with unavoidable positioning errors. The concept of independent contact regions (ICRs) was proposed to deal with this issue by computing for each finger an ICR on the object's boundary such that each finger can be placed anywhere in its ICR to guarantee a force closure grasp. Existing methods for computing ICRs of a polygon requires that each ICR must lie on a single edge of the polygon. This constraint severely limits the size of computed ICRs, especially when the input polygon contains only small edges (e.g., when the polygon is used for representing a curve object). This paper proposes a method for computing the optimal ICRs for frictional two-fingered grasp of a polygon such that each ICR is allowed to extend across consecutive edges of the polygon. The time complexity of the method is O(n2log n), where n is the number of edges of the polygon. Implementation results using several test polygons are presented to exhibit effectiveness of the method.
