Cost-Effective Technologies for Fabrication of PiezoCrystal Vector Velocity Sensors

Arrays of vector velocity sensors provide major system gains over legacy arrays of omnidirectional hydrophones in bottom moored and submarine/unmanned undersea vehicle (UUV) towed applications. For example, the left-right ambiguity of legacy devices is eliminated and an array sensitivity null can be steered at a noisy source of interference making much quieter targets detectable. The exceptionally sensitive, compact accelerometers made possible by the new relaxor piezocrystals are the key enabler for this performance enhancement. Since these sensors are only millimeters in size and are required in large numbers, a major technical hurdle for this technology is to devise cost-effective ways to manufacture the vector sensor. A cost model, relating the component and touch labor costs, is needed for the various design options. Once the dominant cost drivers have been identified, approaches to reducing costs, either through reducing component or labor costs, are essential if the Navy is to benefit from the new technology. A variety of accelerometer designs are under development for these vector velocity sensors, for example, cantilevered-beams, shear-mode, and pressure-gradient devices. While acoustic performance is the primary driver in the choice of device configuration, cost will ultimately determine the acquisition choice.