Detection and tracking of vessels is important in confined areas such as marine parks or harbors. Nowadays, the presence of ships can be accurately monitored either by radar or via AIS system, while small vessels, which have weak radar signature, may be easily missed. The paper presents the detection and localization algorithms optimized for small-and mid-sized boats and based on data either from a single underwater sensor station of four hydrophones, or from data fusion between two hydrophone volumetric arrays. Each platform hosts a sparse tetrahedral array of broadband hydrophones and pan, tilt, compass and depth sensors. Both acoustic and non-acoustic data from the two stations are transferred to shore, where they are stored and processed on a PC. The basis of localization algorithm is the cross-correlation between pairs of hydrophones along time (crosscorrelogram). The wavevector estimation of a vessel from each tetrahedron is achieved through Least Mean Square method. Adequate data association algorithms allow the fusion of estimates obtained from each array in order to provide precise and robust tracking of each vessel. At-sea results demonstrate the system capability for detecting and localizing small vessels in a shallow-water harbor environment. [Work partially funded by EU within ARGOMARINE Project]Published by
The typical 70 mm diameter towed array was developed for blue-water detection at long range and low frequencies in the 1960s. Since then, there has been a need for towed arrays that are lighter and less expensive, especially since the maturing field of autonomous vehicles has expanded the potential of such arrays. The marriage of AUVs and lightweight towed arrays is a natural progression in the development of littoral autonomous sensing networks for applications such Anti-Submarine Warfare, marine mammals, or ambient noise measurements. In August 2007, NURC began to design and build a new thin diameter (31 mm) high-frequency (up to 20 kHz) nested towed array for ASW purposes. An engineering at-sea trial of the array towed by OEX AUV was performed beginning of November 2007. The flow noise level of the array while towed and the potential influence of the AUV self-noise on the acoustic array were also measured. This paper will first describe the array design, its acquisition system and its integration on the OEX AUV. Then, the results obtained from the data analysis are presented. It is shown that the SLITA array has performance that will make it easily fit requirements of the applications previously mentioned.
Search and rescue missions are complex operations. A disaster scenario is generally unstructured, time-varying and unpredictable. This poses several challenges for the successful deployment of unmanned technology. The variety of operational scenarios and tasks lead to the need for multiple robots of different types, domains and sizes. A priori planning of the optimal set of assets to be deployed and the definition of their mission objectives are generally not feasible as information only becomes available during mission. The ICARUS project responds to this challenge by developing a heterogeneous team composed by different and complementary robots, dynamically cooperating as an interoperable team. This chapter describes our approach to multi-robot interoperability, understood as the ability of multiple robots to operate together, in synergy, enabling multiple teams to share data, intelligence and resources, which is the ultimate objective of ICARUS project. It also includes the analysis of the relevant standardization initiatives in multi-robot multi-domain systems, our implementation of an interoperability framework and several examples of multi-robot cooperation of the ICARUS robots in realistic search and rescue missions.
The development of maritime unmanned tools for search and rescue operations is not a trivial task. A great part of maritime unmanned systems developed did not target such application, being more focused on environmental monitoring, surveillance or defence. In opposition to these applications, search and rescue operations need to take into account relevant issues such as the presence of people or other vessels on the water. Building upon user requirements and overall integrated components for assisted rescue and unmanned search operations (ICARUS) system architecture, this chapter addresses the development of unmanned maritime systems. It starts with an overview of the approach where a twotier solution was adopted to address safety issues and then proceeds to detail each of the developed technologies.
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