![]() ![]() Thereafter, active FL strategies that analyze the related fault parameters after executing purposive actuator control are proposed to provide precise fault location. By matching fault features with those of estimated fault parameters, suspected faulty sections are located. Selective features of defined fault parameters are assorted as necessary conditions against different faulty actuators and synthesized in a fault tree subsequently to state the sufficiency towards possible abnormal parts. In this paper, faults occurring on the propulsion and attitude control systems of a torpedo-shaped AUV are analyzed and located while fault features may induce confusions for conventional fault localization (FL). To ensure the mission implementation of Autonomous Underwater Vehicles (AUVs), faults occurring on actuators should be detected and located promptly therefore, reliable control strategies and inputs can be effectively provided. We show that a statistical anomaly detector correctly identifies the strike and effectively highlights it as unexpected behavior for the operator to review. This event is a good example for recent work aimed at detecting faults and performance anomalies onboard in realtime so that operators can be notified. We also provide a damage report - although Tethys was able to complete her mission after the strike, she did not get away without a scratch. We discuss the motion of the vehicle during the strike, its control response after being released by the shark, and the environmental properties it measured near the time of the strike. The operators did not know about the strike until recovering the vehicle normally at the end of the deployment, when the tooth fragments and apparent bite diameter provided sufficient information to identify the shark species. Tethys survived the attack and continued her mission measuring ocean properties in that area for another week. Thirteen minutes after sunrise on September 30, 2013,16.5 m deep in northern Monterey Bay, a white shark (Car-charodon carcharias) struck the MBARI long-range autonomous underwater vehicle (LRAUV) Tethys and left bite grooves in the pressure vessel and tooth fragments embedded in the aft fairing. ![]()
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