Fingertip Fiber Optical Tactile Array with Two-Level Spring Structure.

Jelizaveta Konstantinova,Kaspar Althoefer,Agostino Stilli

doi:10.3390/s17102337

Jelizaveta Konstantinova, Kaspar Althoefer + Show 1 more

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https://doi.org/10.3390/s17102337

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Abstract

Tactile perception is a feature benefiting reliable grasping and manipulation. This paper presents the design of an integrated fingertip force sensor employing an optical fiber based approach where applied forces modulate light intensity. The proposed sensor system is developed to support grasping of a broad range of objects, including those that are hard as well those that are soft. The sensor system is comprised of four sensing elements forming a tactile array integrated with the tip of a finger. We investigate the design configuration of a separate force sensing element with the aim to improve its measurement range. The force measurement of a single tactile element is based on a two-level displacement that is achieved thanks to a hybrid sensing structure made up of a stiff linear and flexible ortho-planar spring. An important outcome of this paper is a miniature tactile fingertip sensor that is capable of perceiving light contact, typically occurring during the initial stages of a grasp, as well as measuring higher forces, commonly present during tight grasps.

Highlights

The problem of tactile perception for grasping along with the development of robotic hands has been extensively studied in recent years
Exploiting the advantages of optical fibres for sensing, we focus on the use of fiber optical technologies for the estimation of applied forces commonly occurring during a grasp
In case the sensor-equipped fingers are moved in order to achieve a tighter grasp, two main scenarios of force feedback can occur: (1) for the rigid object, the contact force is increased until the dome-shaped elements are fully pressed and good contact is established; and (2) the persistent light contact along with the motion of the finger shows that the object is either deflecting or is made from a soft material [25]

Summary

Introduction

The problem of tactile perception for grasping along with the development of robotic hands has been extensively studied in recent years. Finding solutions for tactile perception is critical for the development of multi-fingered robotic hands capable of performing human-like grasping. The use of tactile technologies integrated into multi-fingered robotic hands has been implemented using various approaches. Sensing devices can be the integral part of the structure of the fingertip or can be added to the finger in the form of a thin, skin-like structure [2]. A thin sensing structure added on the fingertip, typically comprises a tactile array, such as in [3,4]. Integrating a tactile or force sensor with a fingertip provides the benefit of measuring multi-dimensional forces, force vector and moments at the point of interest [6,7,8]

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