Sensors 2013, 13(3), 3501-3526; doi:10.3390/s130303501
Article

Ultrasound Indoor Positioning System Based on a Low-Power Wireless Sensor Network Providing Sub-Centimeter Accuracy

CITIC-UGR, TSTC. University of Granada, ETSIIT C/Periodista Daniel Saucedo Aranda s/n 18071,Granada, Spain
* Author to whom correspondence should be addressed.
Received: 22 January 2013; in revised form: 4 March 2013 / Accepted: 11 March 2013 / Published: 13 March 2013
(This article belongs to the Special Issue Last Trends in Acoustic Sensing)
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Abstract: This paper describes the TELIAMADE system, a new indoor positioning system based on time-of-flight (TOF) of ultrasonic signal to estimate the distance between a receiver node and a transmitter node. TELIAMADE system consists of a set of wireless nodes equipped with a radio module for communication and a module for the transmission and reception of ultrasound. The access to the ultrasonic channel is managed by applying a synchronization algorithm based on a time-division multiplexing (TDMA) scheme. The ultrasonic signal is transmitted using a carrier frequency of 40 kHz and the TOF measurement is estimated by applying a quadrature detector to the signal obtained at the A/D converter output. Low sampling frequencies of 17.78 kHz or even 12.31 kHz are possible using quadrature sampling in order to optimize memory requirements and to reduce the computational cost in signal processing. The distance is calculated from the TOF taking into account the speed of sound. An excellent accuracy in the estimation of the TOF is achieved using parabolic interpolation to detect of maximum of the signal envelope at the matched filter output. The signal phase information is also used for enhancing the TOF measurement accuracy. Experimental results show a root mean square error (rmse) less than 2 mm and a standard deviation less than 0.3 mm for pseudorange measurements in the range of distances between 2 and 6 m. The system location accuracy is also evaluated by applying multilateration. A sub-centimeter location accuracy is achieved with an average rmse of 9.6 mm.
Keywords: indoor positioning; ultrasound time-of-flight; wireless sensor network; low power

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MDPI and ACS Style

Medina, C.; Segura, J.C.; De la Torre, Á. Ultrasound Indoor Positioning System Based on a Low-Power Wireless Sensor Network Providing Sub-Centimeter Accuracy. Sensors 2013, 13, 3501-3526.

AMA Style

Medina C, Segura JC, De la Torre Á. Ultrasound Indoor Positioning System Based on a Low-Power Wireless Sensor Network Providing Sub-Centimeter Accuracy. Sensors. 2013; 13(3):3501-3526.

Chicago/Turabian Style

Medina, Carlos; Segura, José C.; De la Torre, Ángel. 2013. "Ultrasound Indoor Positioning System Based on a Low-Power Wireless Sensor Network Providing Sub-Centimeter Accuracy." Sensors 13, no. 3: 3501-3526.

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