Demonstration of Spiral Wavefront Navigation on an Unmanned Underwater Vehicle

In Lab Demonstration of an Underwater Acoustic Spiral Source

“…For synchronization and CIR estimate, a single linear chirp signal between 40 and 50 kHz, with 100 ms of duration, windowed with cosine squared shoulders for 50% of the signal duration [6], was emitted in the four quadrants. Figure 8, shows on the left side the acquired signals, from top to bottom: the synchronization signal, the signal received in the TC4033 hydrophone, and the signal received in the TC4032 hydrophone; and on the right side a zoom of the estimated CIR obtained by cross-correlating the synchronization signals with the signal received in the TC4033 (blue) and in the TC4032 (orange).…”

“…Also in 2012, a different Phased-Spiral source using a radially polarized piezoceramic hollow cylinder, divided in four selective excitation zones, that forms two dipoles with phase biased in quadrature [11]. Later, a reference source was included in the same package (BTech BT-SW1..6) [12], and was employed in the work of the spiral wavefront sonar [13] and in the work of the UUV spiral wavefront navigation [6]. In 2018, Lu et al developed a Phased-Spiral source using 8 longitudinal vibrating elements that vibrate due to multiple piezoelectric ceramic hollow cylinders [14].…”

“…In the Spiral Sonar work [13], a receiving calibration is proposed where the deterministic phase errors are corrected through a polynomial regression. In [6] the spiral source BTech BT-SW06 was characterized, showing the phase errors at different directions.…”

“…Typically, these techniques rely on measuring the time of flight (TOF) of the acoustic signal to perform localization, using multiple omnidirectional hydrophones or/and projectors. Localization solutions based on novel transducers as (i) vector acoustic sensors, which allows to measure the direction of arrival, and (ii) spiral acoustic sources, which generates a spiral acoustic field, have been presented in [3] and [4][5][6] respectively, as promising solutions.…”

“…This underwater localization has the advantage of only needing a single source/hydrophone pair to determine the direction (azimuth or altitude depending on the spiral source orientation). In addition, it has the advantage that does not depend on the TOF to calculate source direction [6].…”