Fault Detection and Prognostic Health Monitoring of Towed Array Sonars

Sonars are used to detect underwater targets and are important tools in maintaining naval superiority. Towed array sonars can operate at very low frequencies thus giving larger ranges and are capable of variable depths of operation. Towed array sonars offer long range surveillance capability and is the sensor of choice for sustained surveillance operations. Reliable operation and maintenance of towed array sonars need effective methods of health monitoring and reliability prediction. Fault detection methods for towed arrays include sensor health monitoring and analyzing their effects on beam former gain. This paper introduces certain metrics that are easily measurable in-situ and which offer insights into the health of the sonar system. These new metrics give direct measureable impact for different failure modes and offer insights into the current health of an operational towed array sonar. Hence, they can be used to build on line prognostic predictions for estimating the remaining useful life of the sonar. Simulation results are shown to demonstrate the effectiveness of the proposed metrics and detailed trial data results from different towed array trials are presented to validate them in operational scenarios.