Sub-Resolution mmWave FMCW Radar-based Touch Localization using Deep Learning

TL;DR

This paper presents a deep learning approach using mmWave radar sensors to achieve sub-resolution touch localization, significantly reducing error compared to traditional methods and enabling real-time implementation.

Contribution

The paper introduces a novel deep learning-based method for mmWave radar touch localization that overcomes inherent resolution limitations and achieves subresolution accuracy.

Findings

2-3x reduction in positioning error compared to conventional methods

Real-time inference capability on general-purpose processors

Successful demonstration of subresolution error performance

Abstract

Touchscreen-based interaction on display devices are ubiquitous nowadays. However, capacitive touch screens, the core technology that enables its widespread use, are prohibitively expensive to be used in large displays because the cost increases proportionally with the screen area. In this paper, we propose a millimeter wave (mmWave) radar-based solution to achieve subresolution error performance using a network of four mmWave radar sensors. Unfortunately, achieving this is non-trivial due to inherent range resolution limitations of mmWave radars, since the target (human hand, finger etc.) is 'distributed' in space. We overcome this using a deep learning-based approach, wherein we train a deep convolutional neural network (CNN) on range-FFT (range vs power profile)-based features against ground truth (GT) positions obtained using a capacitive touch screen. To emulate the clutter characteristics encountered in radar-based positioning of human fingers, we use a metallic finger mounted on a metallic robot arm as the target. Using this setup, we demonstrate subresolution position error performance. Compared to conventional signal processing (CSP)-based approaches, we achieve a 2-3x reduction in positioning error using the CNN. Furthermore, we observe that the inference time performance and CNN model size support real-time integration of our approach on general purpose processor-based computing platforms.