Fault-tolerant variable structure control of an overactuated Dynamic Positioning vessel after thruster failures

In this paper the application of a fault-tolerant control technique for the dynamic positioning of an over-actuated offshore supply vessel to handle abrupt fault on the actuators is proposed. The fault detection is a combination of two model-based techniques: Parity Space Approach and Luenberger observer. Dynamic positioning is provided by a bench of reconfigurable discrete time variable structure controllers, selected by a logic supervisor, based on the fault isolation logic, while an extended Kalman filter is designed for wave filtering. Reported simulations for a scaled model of an offshore supply vessel show that dynamic positioning can be achieved using the proposed solution in case of actuators faults.