Research On Fault Tolerant Control Method Of Control Reconfiguration For Vessel Positioning After Sensor Failures

Dynamic positioning ships are mostly engaged in a higher risk of marine engineeringworks, it has a very strict requirements in positioning accuracy and control stability. As thesensor is the most important device to obtain information in dynamic positioning system, oncethe sensor fails, it will seriously impact the control system’s follow-up monitoring and control.So how to make the dynamic positioning ships achieve or close to the desired controlobjectives on the situation of sensors fault or failure has became a significant research.According to the failure of sensors in ship’s positioning process, this paper proposed a SVMsensor fault diagnosis method based on data analysis and a control reconstruction method offault-tolerant.For fault diagnosis method, this paper mainly use the software method in the case ofnone sensor hardware redundancy. In this paper, support vector machines is used to diagnosissensor fault, for sensor fault types, the multi-classification problem is converted into multiplebinary classification problem by using the binomial tree method, which simplify the designcomplexity of multiclass SVM. This paper used the ship positioning process sensor fault data,Simulated the SVM sensor fault diagnosis in Matlab environment, the simulation resultsdemonstrate the effectiveness of the method.The fault-tolerant method used in this paper is the control reconfiguration fault-tolerantmethod, belongs to an active fault-tolerant control method. The solution of the reconstructionproblem trying to make the smallest changes to the control loop, so that the nominal controllerremain unchanged in the control loop, this control strategy avoid the re-design of thecontroller itself, reducing the complexity of the design. According to the characteristics ofship control, this paper design a sliding mode observer-based virtual sensor to enhance theperformance of fault tolerant by combining the robust sliding mode observer and the virtualsensor.Finally, the fault diagnosis module and the virtual sensor part are used together, constitutea complete fault-tolerant control system. Using the establishment of ship motion model andenvironmental interference model, simulation and analysis the ship positioning process whengyrocompass and DGPS was failure. Simulations included cases of sensor fault-free, fault ofbias, fault of impact and fault of output value constant. The simulation results validate thecontrol reconfiguration fault-tolerant approach has a certain degree of fault tolerance to sensorfault happened in the ship positioning process. In summary, the Fault-tolerant method proposed in this paper is workable,it enhance ship control systems’s performance in faulttolerant, ensure the safety of the ship positioning process,obtain both theoretical and practicalsignificance.