TY - JOUR
T1 - Air-writing via Receiver Array Based Ultrasonic Source Localization
AU - Chen, Hui
AU - Ballal, Tarig
AU - Muqaibel, Ali H.
AU - Zhang, Xiangliang
AU - Al-Naffouri, Tareq Y.
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors would like to thank KAUST Visualization Core Lab for facilitating part of the experimental tests.
PY - 2020
Y1 - 2020
N2 - Air-writing systems have recently been proposed as tools for human-machine interaction where instructions can be represented using letters or digits written in the air. Different technologies have been used to realize air-writing systems. In this paper, we propose an air-writing system using acoustic waves. The proposed system consists of two components: a motion tracking component, and a text recognition component. For motion tracking, we utilize direction-of-arrival (DOA) information. An ultrasonic receiver array tracks the motion of a wearable ultrasonic transmitter by observing the change in the DOA of the signals. We propose a novel 2-D DOA estimation algorithm that can track the change in the direction of the transmitter using measured phase-differences between the receiver array elements. The proposed phase-difference projection (PDP) algorithm can provide accurate tracking with a 3-sensor receiver array. The motion tracking information is passed next for text recognition. To this end, and in order to strike the desired balance between flexibility, processing speed, and accuracy, a training-free order-restricted matching (ORM) classifier is designed. The proposed air-writing system, which combines the proposed DOA estimation and text recognition algorithms, achieves a letter classification accuracy of 96.31%. The utility, processing time, and classification accuracy are compared with four training-free classifiers and two machine learning classifiers to demonstrate the efficiency of the proposed system.
AB - Air-writing systems have recently been proposed as tools for human-machine interaction where instructions can be represented using letters or digits written in the air. Different technologies have been used to realize air-writing systems. In this paper, we propose an air-writing system using acoustic waves. The proposed system consists of two components: a motion tracking component, and a text recognition component. For motion tracking, we utilize direction-of-arrival (DOA) information. An ultrasonic receiver array tracks the motion of a wearable ultrasonic transmitter by observing the change in the DOA of the signals. We propose a novel 2-D DOA estimation algorithm that can track the change in the direction of the transmitter using measured phase-differences between the receiver array elements. The proposed phase-difference projection (PDP) algorithm can provide accurate tracking with a 3-sensor receiver array. The motion tracking information is passed next for text recognition. To this end, and in order to strike the desired balance between flexibility, processing speed, and accuracy, a training-free order-restricted matching (ORM) classifier is designed. The proposed air-writing system, which combines the proposed DOA estimation and text recognition algorithms, achieves a letter classification accuracy of 96.31%. The utility, processing time, and classification accuracy are compared with four training-free classifiers and two machine learning classifiers to demonstrate the efficiency of the proposed system.
UR - http://hdl.handle.net/10754/662701
UR - https://ieeexplore.ieee.org/document/9082625/
U2 - 10.1109/TIM.2020.2991573
DO - 10.1109/TIM.2020.2991573
M3 - Article
SN - 1557-9662
SP - 1
EP - 1
JO - IEEE Transactions on Instrumentation and Measurement
JF - IEEE Transactions on Instrumentation and Measurement
ER -