Synthesizing grasp configurations with specified contact regions

Abstract

This paper presents a new method to solve the configuration problem on robotic hands: determine how a hand should be configured so as to grasp a given object in a specific way, characterized by a number of hand-object contacts to be satisfied. In contrast to previous algorithms given for the same purpose, the one presented here allows specifing such contacts between free-form regions on the hand and object surfaces, and always returns a solution whenever one exists. The method is based on formulating the problem as a system of polynomial equations of special form, and then exploiting this form to isolate the solutions, using a numerical technique based on linear relaxations. The approach is general, in the sense that it can be applied to any grasping mechanism involving lower-pair joints, and it can accommodate as many hand-object contacts as required. Experiments are included that illustrate the performance of the method in the particular case of the Schunk Anthropomorphic hand.

An Open-Source Toolbox for Motion Analysis of Closed-Chain Mechanisms

“…The example in Fig. 3 is simple, but the tools have proved successful in analysing the C-spaces of general 6R robots and Stewart platforms [16], multiloop molecules [17], robot hands with contact constraints [20], or complex multi-loop linkages like the one in Fig. 3.…”

Dexterous grasping under shape uncertainty

“…More recently, hand kinematics has been taken into account when estimating the feasible hand configuration for realizing the grasping points [11,12]. A drawback of this approach is that the valid hand configuration to realize the contacts may not be found.…”

“…For K P , we set it inversely proportional to the variance of the p i , i.e., f cov (p i ) in Eq. (12). The variance of the desired position is along the normal direction f ω (p i ) (Eq.…”

“…(12), and generate grasps with different level of uncertainties. The obtained grasps are ranked according to the sum of uncertainty on each grasping point and the first three grasps with the largest score are selected for implementation on the real robotic hand.…”

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]). …”