Condition Monitoring of the Communication Network in a Remotely Operated Vehicle

Abstract

The demand for Remotely Operated Vehicles (ROVs) in the offshore energy sector is likely to increase in the coming years. Maintaining these high-value assets is important to reduce unexpected downtime, which can lead to financial losses and safety hazards. This thesis focuses on developing condition monitoring concepts for the communication network of three work-class ROVs, two at the Snorre B platform and one at the Visund platform. The main components of the ROV systems are introduced, as well as maintenance and failure modes of ROV systems. Furthermore, an introduction of optical fiber cables are given. How optical fiber is used in ROV systems, the cause of fiber failure and detection of fiber failure are also discussed.

By analysing fiber loss measurements from the three ROV systems, the thesis provides insights into the reliability of fiber cables. Through a combination of data logging, filtering and plotting the fiber loss measurements, the thesis presents old data logging from 2018 and 2019, in addition to new data logging from 2024 that were logged specifically for this thesis. Six different variables are logged, and the increase in fiber signal loss among these variables helps to locate faults within the communication network. A Failure Mode, Effects, and Criticality Analysis (FMECA) highlights the potential risks associated with six critical components of the communication system and offers strategies to improve system reliability. Additionally, box plots of the old and new data logging compare and visually summarize the data by illustrating the level, spread and symmetry of the data. Outliers are identified by the box plots, and by setting predefined limits based on the Q1 quartile or lower whisker, early signs of failure can be detected and corrected.

The results of the thesis emphasize the need for a more reliable and robust logging system and preventative strategies to mitigate the risk of failure in the fiber communication network. By implementing real-time monitoring systems, operators can detect early signs of increased signal loss, preventing major breakdowns and reducing operational costs. The thesis concludes that ongoing research and improved data collection will help optimize ROV maintenance procedures and increase system reliability.