A Forward Array Looking Wide Band Phased Sonar For Autonomous Vehicles (AUV)

~ b s t r a c t Basic to the success of almost all AUV missions is the ability of a vehicle to detect and in many cases m, not just turn away from, an obstacle dead ahead. This requirement is made considerably more challenging when an AUV operates in shallow water because boundary reverberation will degrade acoustic sensor performance. Sensors currently available for forward mounting into an AUV either do not have adequate directional discrimination to allow for shallow water operation or they operate at a frequency so high that detection range and (as a result) forward speed are severely limited. A forward-looking phased array sonar that operates over a wide frequency range (50200 kHz) can detect obstacles at long ranges and provide fairly precise images of objects at short ranges. For specialized missions, this sonar would operate in concert with specialized mission sensors to provide performance gains in search, detection, classification, and vehicle control. NUWC is currently working with Raytheon, Submarine Signal Division, to demonstrate a wideband (50-200 kHz) phased array sonar for small underwater submersibles. By the end of Ey92, a 12 x 12 inch, 1600 element receive array, operating at 30% sparseness (500 individual element channels) will be fabricated and tested. During the course of this effort, new technology has been developed that configures single sheets of polyvinylidene diflouride polymer (PVDF) into densely populated arrays of independent acoustic sensors. This technology provides unprecedented flexibility in the design of acoustic receive arrays, making it feasible and affordable to configure acoustic receivers for specialized applications. The NUWC array is being configured to a plane surface, but this technology makes application of complex phased arrays to a curved surface a practical option.