Sound of Touch: Active Acoustic Tactile Sensing via String Vibrations

TL;DR

This paper introduces Sound of Touch, a scalable active acoustic tactile sensing method using vibrating strings and pickups to detect contact location, force, and slip in real-time, supported by physics-based modeling.

Contribution

It presents a novel string-based tactile sensing hardware, a physics-grounded simulation tool, and a real-time inference pipeline for contact detection.

Findings

Achieves millimeter-scale contact localization

Reliable estimation of normal force

Real-time slip detection capability

Abstract

Distributed tactile sensing remains difficult to scale over large areas: dense sensor arrays increase wiring, cost, and fragility, while many alternatives provide limited coverage or miss fast interaction dynamics. We present Sound of Touch, an active acoustic tactile-sensing methodology that uses vibrating tensioned strings as sensing elements. The string is continuously excited electromagnetically, and a small number of pickups (contact microphones) observe spectral changes induced by contact. From short-duration audio signals, our system estimates contact location and normal force, and detects slip. To guide design and interpret the sensing mechanism, we derive a physics-based string-vibration simulator that predicts how contact position and force shift vibration modes. Experiments demonstrate millimeter-scale localization, reliable force estimation, and real-time slip detection. Our contributions are: (i) a lightweight, scalable string-based tactile sensing hardware concept for instrumenting extended robot surfaces; (ii) a physics-grounded simulation and analysis tool for contact-induced spectral shifts; and (iii) a real-time inference pipeline that maps vibration measurements to contact state.