Robust Fault Tolerant Control For Course Keeping Of Vessels

It is an essential national development strategy to exploit,utilize and protect the seas and oceans,and build China into a maritime power.The Belt and Road initiative was proposed by China to build a "Silk Road Economic Belt" and "maritime Silk Road".The transport of cargoes on water is particularly important under the background of the Belt and Road initiative arid the construction of a maritime power.As the main carrier of cargo transportation by waterways,ships will suffer complex hydrologic and meteorological conditions during navigation,and with the development of the times and the progress of science and technology,large scale,complexity and specialization of ships have become a trend.Once faults occur on the ship’s equipment,it cannot be operated normally,this situation may lead to problems of the whole ship,and then lead to the delay of normal ship schedule or the occurrence of ship accidents.The consequences of ship accidents cannot be estimated.Therefore,it is necessary to judge the faults that may occur in the operation of the ship,and carry out fault-tolerant control for the faults,so that it can maintain normal operation or ensure the overall safety in the case of reducing some ship performance.In this paper,the closed-loop gain shaping algorithm is used to design the PID controller,then the nonlinear feedback and decoration(NFAD)technology based on power function was applied to the course keeping control of ships,the wind and wave interference and the characteristics of steering gear were added to the simulation to make the simulation closer to the ship reality.The accuracy of the ship model was verified by comparing the data of cycle simulation and sea trial test.The nonlinear feedback technology based on power function is added to carry out the simulation of course keeping control of ships for the purpose of optimizing the effect of the control.The simulation test of course keeping control is carried out by building a motion model with the parameters of "Yukun" ship,a practice ship of Dalian Maritime University.The experimental results are analyzed to verify the effectiveness of the NFAD technology and the improvement of the control performance.Considering the faults those may occur on the sensors or actuators,these faults can be divided to several kinds,such as instantaneous fault,short-term fault and long-term fault on common sensors and actuators faults in ship course keeping.The fault diagnosis and isolation technology were considered to judge if the faults occurred or not.The fault diagnosis and isolation were designed on the basis of no need to redesign the controller to insure the robustness of the entire system,so the ship can achieve the expected operation effect in case of sensor or actuator fault.The simulation results proved the validity of the fault diagnosis and isolation method,which can prevent the ship from losing control due to the possible faults in the course keeping.