Haptic Edge Detection Through Shear.

Jonathan Platkiewicz,Hod Lipson,Vincent Hayward

doi:10.1038/srep23551

Jonathan Platkiewicz, Hod Lipson + Show 1 more

Open Access

https://doi.org/10.1038/srep23551

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Abstract

Most tactile sensors are based on the assumption that touch depends on measuring pressure. However, the pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium. Currently, there is no consensus as to which components of strain are most informative for tactile sensing. Here, we propose that shape-related tactile information is more suitably recovered from shear strain than normal strain. Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals.

Highlights

Most tactile sensors are based on the assumption that touch depends on measuring pressure
The pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium
Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed

Summary

Introduction

Most tactile sensors are based on the assumption that touch depends on measuring pressure. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals. These discrepancies, often attributed to the complexities of skin mechanics, may be a reflection of the fact that at the length-scale of the mechanoreceptors, the www.nature.com/scientificreports/

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