46 drift rates and acoustic navigation signals, ensuring that the vehicle maintains an accurate sense of position. Doppler Velocity Logs offer precise velocity readings over the seabed, bolstering navigation, while roll, pitch, yaw and heading metrics ensure stability and accurate trajectory. Communication systems, often the lifeline between operators and UUVs, present their own challenges. Engineers monitor bit-error rates, signal-tonoise ratios and bandwidth to ensure effective data transmission. Latency and link stability are constantly under scrutiny to prevent interruptions. Whether through acoustic or optical signals, robust communication systems are essential for transferring telemetry and maintaining control. The payload and sensor systems require calibration checks and ongoing monitoring of data integrity. Proper management of storage capacity and active payload systems guarantees that no critical data or operational capabilities are lost during missions. Effective performance monitoring can be realised by combining real-time telemetry data with onboard logging systems. Anomaly detection algorithms flag unusual and unexpected data while fault detection, isolation and recovery systems provide automated solutions, ensuring that even when problems arise, the mission can continue or the vehicle can safely return. Large UUV monitoring The introduction of large-displacement and extra-large UUVs with increased endurance on the order of weeks to months is driving the need for higher levels of reliability and consequently more performance monitoring. This is driving a Condition-Based UUV Maintenance Monitoring and Prediction System (C-BUMMPS) architecture with onboard sensing, monitoring and processing elements, in addition to onshore testing, data analytics and maintenance activities. This uses a model-based systems engineering approach where the requirements of the analysis process were drawn from three distinct efforts. First was the stakeholder analysis, conducted to elicit the stakeholder needs and then translate them into requirements. These yielded both functional and non-functional requirements for the C-BUMMPS architecture. Next, the system operations were refined through further development of the operational situations, yielding C-BUMMPS functions that must be performed to support the operational activities. Finally, a generic UUV physical architecture was developed and underwent failure mode and detection analysis. This yielded additional functional requirements for how the C-BUMMPS might detect failures. As well as vibration analysis, the monitoring architecture covers temperature measurements – using infrared cameras where temperature sensors are not viable – together with acoustic and ultrasonic monitoring, oil analysis, and voltage and current measurements. A generic UUV physical hierarchy that can be adapted according to the specific needs and requirements of a UUV is a better approach than deriving a hierarchy for a specific UUV class, and this generic UUV physical hierarchy was derived from the Unmanned Maritime System. However, there is a challenge in using generic architecture developed for large and extra-large UUVs with the smaller Class C craft that might not have the space or resources to implement condition monitoring. At the same time, the UUV conditionbased maintenance system needs to use data from across all classes of craft to take advantage of common components and to correlate performance, degradation and failure modes across similar subsystems. The data can also be used to project estimated life cycles of components and subsystems to budget for spares and maintenance. The developed architecture consists of onboard sensing, monitoring and processing elements on the UUV, in addition to the onshore testing, data August/September 2025 | Uncrewed Systems Technology Focus | Performance monitoring The operational model of C-BUMMPS (Image courtesy of the US Naval Postgraduate School)
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