Fault Tolerant Control For Dynamic Positioning System Of Ships With Actuator Fault

It is the first time that "Expanding the Economic Space of the Blue" has been listed into "the 13th Five-year Plan",and it has been made clear that the development of marine science and technology should focus on making breakthrough of marine areas with safety and environmental protection in deep-water,which provides the guaidance for the improvement of deep-water equipment and technology.Due to the risk of deepwater operations,much higher requirements on the safety and reliability of the deep-water equipment and technology have been put forward.The International Maritime Organization and The Classification Societies have already made provision that high-level secure Dynamic Position System(DPS)should guarantee that any system which supports DPS will not be suffered to lose the position when there is a single failure.Actuator faults are inevitable in harsh environment.The study of fault tolerant control of the ship's DPS will effectively improve the reliability and the safety of the DPS.At the same time,the redundant configuration of the actuator of the high level dynamic positioning system provides the hardware foundation for the fault tolerant control.In this paper,a mathematical model of ship's DPS with actuator fault is established.And based on the model obtained,the paper studies the detection and the isolation of the actuators's fault under the assumptions that the yaw angle is small and the perturbation boundary is known.Meanwhile,based on the information obtained,the fault tolerant control is implemented by using the control law reconfiguration method.Then,considering the non-linear characteristics of the ship's DPS,a hybrid fault tolerant controller is proposed while the passive fault tolerant control and active fault tolerant control are combined together with the assumption that the disturbance boundary is known.The method not only overcomes delay constraint problems which rely on reconstruction by the fault-tolerant control of fault diagnosis subsystem solely,but also improves the dynamic positioning vessel tolerant control performance.Finally,the complex problems about fault detection and isolation are avoided through designing a sliding mode observer to estimate the fault and compensate the disturbance in real time and making compensation for fault and disturb in real time based on the designed adaptive fault tolerant controller when the characteristics of the unknown external disturbance are taken into consideration and the discrete structure of the switch between passive and active fault tolerant control is addressed.Finally,referring to the parameters of a marine vessel,simulations of the designed ship's DPS fault diagnosis and fault tolerant control are carried out respectively in Matlab/Simulink environment.The simulation results verify the validity of the designed method.