This paper proposes the underwater terrain map building method based on the occupancy grids by using 3D point cloud from the polar sonar sensor system. Because it is expensive to use current 3D underwater sonar sensors, the low-cost 3D sensor systems are needed for the generalized purposes. So the polar-styled sonar sensor system was designed and implemented. It was constructed on the rotating ...

The paper discusses the use of dual stave forward-looking sonar to build a threedimensional underwater model for navigation in restricted waterways. The sonar normally provides separate horizontal and vertical images but when the information is synthesized into a single three-dimensional model it permits, in certain circumstances, the AUV to plan and carry out a trajectory where no path is othe...

Progress in the implementation of state-of-the-art signal processing schemes in sonar systems has been limited mainly by the moderate advancements made in sonar computing architectures and the lack of operational evaluation of the advanced processing schemes. Until recently, sonar computing architectures allowed only fast-Fourier-transform (FFT), vector-based processing schemes because of their...

The advances in robotics and imaging technologies have brought various imaging devices to the field of the unmanned exploration of new environments. Forward looking sonar is one of the newly emerging imaging methods employed in the exploration of underwater environments. While the video sequences produced by forward looking sonar systems are characterized by low signal-to-noise ratio, low resol...

Ultrasonic emissions of bats are directional and delimit the echo-acoustic space. Directionality is quantified by the aperture of the sonar beam. Recent work has shown that bats often widen their sonar beam when approaching movable prey or sharpen their sonar beam when navigating through cluttered habitats. Here we report how nose-emitting bats, Phyllostomus discolor, adjust their sonar beam to...

Chronic neural recordings were taken from the midbrain superior colliculus (SC) of echolocating bats while they were engaged in one of two distinct behavioral tasks: virtual target amplitude discrimination (VTAD) and real oscillating target tracking (ROTT). In the VTAD task, bats used a limited range of sonar call features to discriminate the amplitude category of echoes, whereas in the ROTT ta...

The sonar beam of an echolocating bat forms a spatial window restricting the echo information returned from the environment. Investigating the shape and orientation of the sonar beam produced by a bat as it flies and performs various behavioral tasks may yield insight into the operation of its sonar system. This paper presents recordings of vertical and horizontal cross sections of the sonar be...

There is increasing concern that human-produced ocean noise is adversely affecting marine mammals, as several recent cetacean mass strandings may have been caused by animals' interactions with naval 'mid-frequency' sonar. However, it has yet to be empirically demonstrated how sonar could induce these strandings or cause physiological effects. In controlled experimental studies, we show that mid...

Affected by the residual of time varying gain, beam patterns, angular responses, and sonar altitude variations, radiometric distortion degrades the quality of side-scan sonar images and seriously affects the application of these images. However, existing methods cannot correct distortion effectively, especially in the presence of seabed sediment variation. This study proposes a new radiometric ...