Improved Proximity, Contact, and Force Sensing via Optimization of Elastomer-Air Interface Geometry

TL;DR

This paper introduces an optimized elastomer-air interface design for a fingertip-mounted optical sensor that seamlessly integrates proximity, contact, and force sensing for robotic manipulation, enhancing measurement accuracy and operational range.

Contribution

The authors present a novel sensor design that improves invariance, signal-to-noise ratio, and multi-regime operation by optimizing the elastomer-air boundary and leveraging time-of-flight technology.

Findings

Seamless transition between distance and force measurement modes.

Enhanced invariance to object reflectivity and noise.

Open hardware and software for easy replication.

Abstract

We describe a single fingertip-mounted sensing system for robot manipulation that provides proximity (pre-touch), contact detection (touch), and force sensing (post-touch). The sensor system consists of optical time-of-flight range measurement modules covered in a clear elastomer. Because the elastomer is clear, the sensor can detect and range nearby objects, as well as measure deformations caused by objects that are in contact with the sensor and thereby estimate the applied force. We examine how this sensor design can be improved with respect to invariance to object reflectivity, signal-to-noise ratio, and continuous operation when switching between the distance and force measurement regimes. By harnessing time-of-flight technology and optimizing the elastomer-air boundary to control the emitted light's path, we develop a sensor that is able to seamlessly transition between measuring distances of up to 50mm and contact forces of up to 10 newtons. Furthermore, we provide all hardware design files and software sources, and offer thorough instructions on how to manufacture the sensor from inexpensive, commercially available components.