A new robotic hand based on the design of fingers with spatial motions

TL;DR

This paper introduces a novel robotic hand with three under-actuated fingers capable of spatial movements, enabling complex grasping of irregularly shaped objects, especially for industrial applications involving machined workpieces.

Contribution

It extends under-actuated finger design to include spatial movements, enhancing grasping versatility without additional actuators or sensors.

Findings

Successfully models finger kinematics and stability.

Demonstrates grasping of complex shapes like cylindrical and spherical objects.

Provides CAD models and force transmission analysis.

Abstract

This article presents a new hand architecture with three under-actuated fingers. Each finger performs spatial movements to achieve more complex and varied grasping than the existing planar-movement fingers. The purpose of this hand is to grasp complex-shaped workpieces as they leave the machining centres. Among the taxonomy of grips, cylindrical and spherical grips are often used to grasp heavy objects. A combination of these two modes makes it possible to capture most of the workpieces machined with 5-axis machines. However, the change in grasping mode requires the fingers to reconfigure themselves to perform spatial movements. This solution requires the addition of two or three actuators to change the position of the fingers and requires sensors to recognize the shape of the workpiece and determine the type of grasp to be used. This article proposes to extend the notion of under-actuated fingers to spatial movements. After a presentation of the kinematics of the fingers, the problem of stability is discussed as well as the transmission of forces in this mechanism. The complete approach for calculating the stability conditions is presented from the study of Jacobian force transmission matrices. CAD representations of the hand and its behavior in spherical and cylindrical grips are presented.