Supervisory Control of Line Breakage for Thruster-Assisted Position Mooring System
Chapter, Conference object, Peer reviewed
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Original versionBlanke, Mogens; Galeazzi, Roberto [Eds.] 10th IFAC Conference on Manoeuvring and Control of Marine Craft (MCMC 2015) IFAC-PapersOnLine, Elsevier, 2015
Thruster-assisted position mooring (TAPM) is an energy-efficient and reliable stationkeeping method for deep water structures. Mooring line breakage can significantly influence the control system, and ultimately reduce the reliability and safety during operation and production. Therefore, line break detection is a crucial issue for TAPM systems. Tension measurement units are useful tools to detect line failures. However, these units increase the building cost of the system, and in a large portion of existing units in operation line tension sensors are not installed. This paper presents a fault-tolerant control scheme based on estimator-based supervisory control methodology to detect and isolate a line failure with only position measurements. After detecting a line break, a supervisor switches automatically a new controller into the feedback loop to keep the vessel within the safety region. Numerical simulations are conducted to verify the performance of the proposed technique, for a turret-based mooring system.