Fault-tolerant Control Of Ship Course Switching Based On Limited State Output

In the context of the national vigorous promotion of the Silk Road Economic Belt and the 21 st Century Maritime Silk Road and the development strategy of shifting from a large maritime power to a strong maritime power,vigorous development of maritime transportation plays an important role.As an important carrier of world maritime trade,ships play an indispensable role in maritime transportation.Ship motion control has always been a popular research direction in the field of navigation science and technology,which has attracted wide attention from experts and scholars.As we all know,ships face complex sea conditions and meteorological conditions in the process of sea navigation and transportation,and with the continuous development and progress of science and industry,ships are developing in the direction of specialization,intelligence and enlargement.Once the ship’s actuators malfunction failed or partially failed,the control system will not operate normally,which will lead to the delay of normal ship production plan or ship accidents.The delay of ship arrival deadline will bring economic loss,and the consequences of ship accident(such as collision,grounding,etc.)will be incalculable.In addition,in nautical practice,the actuators of the ship control system are susceptible to physical and environmental constraints,most notably the limited operating range of the ship’s actuators.When the actuators of the control system are not able to execute the commands required by the ship controller signals well,the most direct result will be to cause system vibration and even lead to control system instability.Based on the above,it is of practical significance to study the fault-tolerant control of ship heading switching with restricted state output.This thesis firstly designs a fault-tolerant controller for ship heading switching based on the output constraint.Considering the output error constraint problem of the course keeping control system,the Barrier Lyapunov Function(BLF)and multi-state output constraint priming are used to deal with the output error constraint problem of the course keeping control system and constrain the course error within the dynamic range,secondly,for the ship actuator failure problem,by setting the monitoring function and Secondly,for the ship actuator failure problem,the actuator failure monitoring and the ability to switch from the failed actuator to the healthy actuator in the case of uncertain failure mode are realized,which can guarantee the boundedness of the tracking error and the stability of the system.Subsequently,the backstepping method and Lyapunov stability theory are used to convert the heading error by constructing an error conversion function by combining the prescribed performance function and the switching fault-tolerant control method.Combining the prescribed performance function with the barrier Lyapunov function effectively limits the transient performance of the ship heading error,ensures the steadystate tracking performance,and limits the heading error of the system to the predefined stability boundary,and estimates the uncertainty term of the mathematical model of ship motion to design a ship adaptive switching fault-tolerant heading controller.Once the ship actuator fails,it will automatically switch to the next healthy actuator,thus ensuring the stability of the system.Through theoretical analysis,it is proved that the course keeping control system is effective and stable under the action of fault-tolerant controller.Finally,taking a container ship with two propellers and two rudders as the simulation object,and the Matlab simulation experiments are conducted to simulate the abovedesigned ship heading-keeping controller respectively.