Determining Force-Closure Grasps Reachable by a Given Hand

Abstract

The paper presents an approach to find contact points on an object surface that are reachable by a given hand and such that the resulting grasp satisfies the force-closure condition. This is a very common problem that still requires a practical solution. The proposed method is based on the computation of a set of independent contact regions on the object boundary such that a finger contact on each region produce a force-closure grasp, and then this set of regions is iteratively recomputed while looking for a set of contact points that are reachable by a given hand. The search is done guided by a cost function that indicates the proximity of the hand fingertips to a candidate set of grasping contact points. The approach has been implemented for the Schunk Anthropomorphic Hand and planar objects, and application examples are included to illustrate its performance.

Grasping bulky objects with two anthropomorphic hands

“…• In the main loop three points are randomly selected, one from S t and two from S f , an ID is assigned to the candidate triplet in order to verify if this combination has not been formed before (line [13][14][15][16][17][18]. Then, the distances between the fingers are computed and the condition in eq.…”

“…Many of this approaches use optimization methods to find valid hand configurations [12], [13], [14], [15], [16], or discretize the workspace of the hands in order to simplify the search of suitable poses of the fingers on the object surface [17], [18], [19], or select the best grasp using a set of grasp quality metrics [20], [21].…”

Planning manipulation movements of a dual-arm system considering obstacle removing

“…When a predetermined grasping configuration is not actually reachable for the current pose of the object it will be properly disregarded during the planning process, this may happen due to hand or arm kinematic constraints or due to collisions with fixed obstacles. The grasping configurations for each object can be obtained using different procedures (see for instance [31,32]). …”

Searching force-closure optimal grasps of articulated 2D objects with n links

“…This work does not take into account the particular device used for the grasp as it is done for rigid objects by Roa et al (2011);Gilart and Suárez (2012), so it may happen that the contact points of the optimal grasp procedure were nor reachable by a particular robotic hand. Nevertheless the approach is always useful for object fixturing in industrial applications.…”