# High-Resolution Contact Localization and Three-Axis Force Estimation with a Sparse Strain-Node Tactile Interface Device

## TL;DR

This paper introduces a tactile device that can accurately detect contact points and forces using a minimal number of sensors, enabling efficient and cost-effective robotic interaction.

## Contribution

The novel SSTID device and SCDF framework enable joint contact localization and three-axis force estimation with only nine strain channels.

## Key findings

- The SSTID device achieves accurate contact localization and three-axis force estimation using nine strain channels.
- The SCDF framework, trained via a two-stage sim-to-real strategy, enables full-workspace characterization.
- The approach supports low-cost and scalable deployment of sparse tactile interfaces.

## Abstract

High-resolution contact localization and three-axis force estimation are crucial for human–robot interaction and precision manipulation, yet the sensing area is limited by channel density and wiring cost. Sparse strain readout makes joint estimation of location and three-axis force challenging due to cross-axis coupling and nonlinear responses, while dense arrays or extensive calibration increase complexity. We present a sparse strain-node tactile interface device (SSTID) whose three-module layout is optimized via particle swarm optimization to maximize informative response overlap, enabling contact localization (x,y) and three-axis force (Fx,Fy,Fz) estimation using only nine strain channels. We further propose a strain-node contact-state decoding framework (SCDF) implemented with a lightweight multilayer perceptron and trained via a two-stage sim-to-real strategy, including FEM pretraining followed by few-shot real-data adaptation. Experiments demonstrate accurate contact-state decoding with full-workspace characterization, supporting low-cost and scalable deployment of sparse tactile interfaces.