NUSense: Robust Soft Optical Tactile Sensor

TL;DR

This paper introduces NUSense, an optical tactile sensor that detects shear strain via color ink deformation in a silicone layer, offering a robust method for tactile sensing based on continuum mechanics principles.

Contribution

The work presents a novel shear strain-based optical tactile sensing principle and validates it with a camera-based sensor, expanding tactile sensing capabilities beyond pressure measurement.

Findings

Sensor effectively measures shear strain through color ink deformation.

Robustness confirmed through multiple load cycles with a robot arm.

Potential applications include force sensing and contact localization.

Abstract

While most tactile sensors rely on measuring pressure, insights from continuum mechanics suggest that measuring shear strain provides critical information for tactile sensing. In this work, we introduce an optical tactile sensing principle based on shear strain detection. A silicone rubber layer, dyed with color inks, is used to quantify the shear magnitude of the sensing layer. This principle was validated using the NUSense camera-based tactile sensor. The wide-angle camera captures the elongation of the soft pad under mechanical load, a phenomenon attributed to the Poisson effect. The physical and optical properties of the inked pad are essential and should ideally remain stable over time. We tested the robustness of the sensor by subjecting the outermost layer to multiple load cycles using a robot arm. Additionally, we discussed potential applications of this sensor in force sensing and contact localization.