Air-Writing Character Recognition with Ultrasonic Transceivers
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AuthorSáez Mingorance, Borja; Méndez Gómez, Javier; Mauro, Gianfranco; Castillo Morales, María Encarnación; Pegalajar Cuéllar, Manuel; Morales Santos, Diego Pedro
UltrasoundAir-writingGesture recognitionDeep learning
Saez-Mingorance, B.; Mendez-Gomez, J.; Mauro, G.; Castillo-Morales, E.; Pegalajar-Cuellar, M.; Morales-Santos, D.P. Air-Writing Character Recognition with Ultrasonic Transceivers. Sensors 2021, 21, 6700. https://doi.org/10.3390/s21206700
SponsorshipProject “SEMULIN” (German project number 19A20012D); German Federal Ministry for Economic Affairs and Energy (BMWi); Project P20-00265 funded by the “Junta de Andalucia” of Spain
The interfaces between users and systems are evolving into a more natural communication, including user gestures as part of the interaction, where air-writing is an emerging application for this purpose. The aim of this work is to propose a new air-writing system based on only one array of ultrasonic transceivers. This track will be obtained based on the pairwise distance of the hand marker with each transceiver. After acquiring the track, different deep learning algorithms, such as long short-term memory (LSTM), convolutional neural networks (CNN), convolutional autoencoder (ConvAutoencoder), and convolutional LSTM have been evaluated for character recognition. It has been shown how these algorithms provide high accuracy, where the best result is extracted from the ConvLSTM, with 99.51% accuracy and 71.01 milliseconds of latency. Real data were used in this work to evaluate the proposed system in a real scenario to demonstrate its high performance regarding data acquisition and classification.