Designing robot grippers: optimal edge contacts for part alignment

Abstract

Although parallel-jaw grippers play a vital role in automated manufacturing, gripper surfaces are still designed by trialand-error. This paper presents an algorithmic approach to designing gripper jaws that mechanically align parts in the vertical (gravitational) plane. We consider optimal edge contacts, based on modular trapezoidal segments that maximize contact between the gripper and the part at its desired final orientation. Given the n-sided 2D projection of an extruded convex polygonal part, mechanical properties such as friction and center of mass, and initial and desired final orientations, we present an O(n 3 log n) numerical algorithm to design optimal gripper jaws. We also present an O(n log n) algorithm to compute tolerance classes for these jaws, and report on an online implemented version of the algorithm and physical experiments with the jaws it designed. This paper extends earlier results that generated optimal point contacts [M. T. Zhang and K. Goldberg, "Gripper point contacts for part alignment," IEEE Trans. Robot. Autom. 18(6), 902-910 (2002)].

Task and Context Sensitive Gripper Design Learning Using Dynamic Grasp Simulation

“…Aligning objects enables more secure grasps and by that enables more accurate placement. Gripper jaw design for object alignment was investigated in [14][15][16][17]. In [16] they define a modular gripper surface based on trapezoidal segments for which they present an algorithm that can optimize the gripper design such that a specific alignment of the object is obtained when it is grasped from the top.…”

Optimizing grippers for compensating pose uncertainties by dynamic simulation

“…The gripper jaw design for the purpose of secure grasping and object alignment has also been studied extensively in [8]- [10]. In [10] a parameterization of a modular gripper surface is introduced, and an optimization algorithm to achieve specific object alignment is presented. In [2], the convex-hull based finger shapes are investigated in terms of alignment.…”

Finger design automation for industrial robot grippers: A review

“…Completing the presented design process in Fig. 2, which consists of an iterative trial and error procedure, may take several weeks for an expert, while the agile market demands a quick design process (Zhang and Goldberg, 2007). As a result, automated finger design is of the highest importance for the robotic industry in order to comply with agile manufacturing (Velasco and Newman, 1998).…”