underwater target imaging using acoustic waves is possible by employing the method used in synthetic aperture radars. in recent years, synthetic aperture sonar has been the subject of several researches. wherein imaging of underwater moving target is required, inverse synthetic aperture sonar (isas) idea can be used but specifications and limitations of underwater channel should be considered. ...

adapts beamforming tools developed for passive sonar and seismological applications for use in AE source localization and signal discrimination analyses. Instead of relying on the relatively weak P-wave, this method uses the energy-rich Rayleigh wave and requires only a small array of 4–8 sensors. Tests on an in-service reinforced concrete structure demonstrate that the azimuth of an artificial...

The paper describes several approaches and experimental results for learning a map of an indoor environment, using a combination of odometry, sonar range sensors, and vision. The aim of the presented research work is consistent real-time map-learning in indoor-environments with low-cost sensors and limited computational resources and without installations in the environment itself. Therefore, w...

We present work towards building a fused sensing system for a small Autonomous Surface Vessel (ASV). We present a technique to estimate the extrinsic calibration of a forward facing monocular camera by using existing range sensors on the vessel along with a some improvements on segmenting the water surface in the camera images. We demonstrate our techniques in field experiments and apply the ob...

Autonomous underwater vehicles (AUVs) are typically used to “actively” probe the ocean, using sensors that are mounted on a vehicle that moves through the water column. A more challenging task is to use an AUV to position a bottom-mounted stationary platform, such as a passive sonar that requires a large aperture. This paper describes the development of a passive sonar, which was mounted as a p...

We present initial progress on so-called extended visual servoing, an integrated approach of controlling mobile robots equipped with multiple sensors. Our approach to sensor fusion uses the mathematical framework of visual servoing for a higher dimensional feature space that incorporates other sensors in addition to vision (which still plays a central role). Analysis and simulation on a planar ...

Utilization of non-destructive and non-invasive methods for the real-time underwater remote sensing is one of the challenging and desired tasks in the maritime security and safety as well as the harbour surveillance. Our aim was to develop and verify advanced electromagnetic sensors for a seabed objects detection and inspection. The seabed is a complex environment often covered with the sand, d...

Autonomous robots can use a variety of sensors, such as sonar, laser range finders, and bump sensors, to sense their environments. Visual information from an onboard camera can provide particularly rich sensor data. However, processing all the pixels in every image, even with simple operations, can be computationally taxing for robots equipped with cameras of reasonable resolution and frame rat...

Double pulse coding is used to give sonar sensors a distinctive 'voice', allowing several to operate concurrently in the same acoustic space. This paper describes the use of random spacing between the two pulses to overcome interference problems arising when the same spacing.occurs between targets or ··is used by another •·•··•.. sensor. Results demonstrate the robustness ·of this method in com...

Anti-submarine warfare(ASW) is a critical challenge for maintaining a fleet presence in hostile areas. Technology advancement has allowed submarines to evade standard sonar detection. A viable alternative is to place magnetic or acoustic sensors in close proximity to possible underwater pathways of submarines. This approach may require deploying large-scale underwater sensor networks to form 3-...