A Virtual 2D Tactile Array for Soft Actuators Using Acoustic Sensing

TL;DR

This paper introduces a novel acoustic sensing-based virtual 2D tactile array for soft actuators, capable of high-resolution contact detection, shape recognition, and localization, using embedded audio components and machine learning.

Contribution

It presents a new acoustic tactile sensing method integrated into soft actuators, enabling detailed contact and shape detection with high spatial resolution and accuracy.

Findings

Localization error of 1.67 mm in x-direction and 0.0 mm in y-direction

Detection of single-pin contacts with 0.17 N force accuracy

88% classification rate for Braille letter recognition

Abstract

We create a virtual 2D tactile array for soft pneumatic actuators using embedded audio components. We detect contact-specific changes in sound modulation to infer tactile information. We evaluate different sound representations and learning methods to detect even small contact variations. We demonstrate the acoustic tactile sensor array by the example of a PneuFlex actuator and use a Braille display to individually control the contact of 29x4 pins with the actuator's 90x10 mm palmar surface. Evaluating the spatial resolution, the acoustic sensor localizes edges in x- and y-direction with a root-mean-square regression error of 1.67 mm and 0.0 mm, respectively. Even light contacts of a single Braille pin with a lifting force of 0.17 N are measured with high accuracy. Finally, we demonstrate the sensor's sensitivity to complex contact shapes by successfully reading the 26 letters of the Braille alphabet from a single display cell with a classification rate of 88%.