Multi-Sonar Integration and the Advent of Senor Intelligence

The subsea environment represents the last major frontier of discovery on Earth. It is envisioned that exploration of the seabed, in both our deep-ocean and inshore waters, will present a multitude of potential economic opportunities. Recent interest in the everexpanding exploration for valuable economic resources, the growing importance of environmental strategies and the mounting pressure to stake territorial claims, has been the main motivation behind the increasing importance of detailed seabed mapping, and rapid advancements in sensor technology and marine survey techniques (McPhail, 2002; Nitsche et al., 2004; Desa et al., 2006; Niu et al., 2007). Over the past decade, there has been an increasing emphasis on the integration of multiple sonar sensors during marine survey operations (Wright et al., 1996; Laban, 1998; Pouliquen et al., 1999; Yoerger et al., 2000; Duxfield et al., 2004; Kirkwood et al., 2004). The synergies offered by fusing and concurrently operating multiple acoustic mapping devices in a single survey suite underpin the desire for such an operational configuration; facilitating detailed surveying of the ocean environment, while enabling the information encoded in one instrument’s dataset to be used to correct artefacts in the other. Innovative advancements in the intelligence of sensors have permitted time-critical decisions to be made based on the assessment of real-time environmental information. Inmission data evaluation and decision making allows for the optimisation of surveys, improving mission efficiency and productiveness. While low-frequency ( 200kHz) imaging sonar generates high-resolution datasets, providing greater detail and improving data analysis. High-frequency sonar systems are therefore the desired sensor systems used during seabed survey missions. However, seawater severely restricts acoustic wave propagation, reducing the range (field of view) of high-resolution sonar in particular. Consequently, high-resolution survey sensors must be deployed in close-proximity to the seabed. UUVs are ideal platforms for providing the nearseabed capability required, and often demanded, by marine survey operations (McPhail, 2002). Furthermore, recent technological advancements have allowed UUVs to provide highresolution survey capabilities for the largely unexplored deep-water environments, previously considered uneconomical or technically infeasible (Whitcomb, 2000). O pe n A cc es s D at ab as e w w w .in te ch w eb .o rg