Research On Stabilization Control And Application Of Ship Dynamic Positioning System Based On Observer

With the shortage of land resources,people have gradually shifted the battlefield for resource acquisition to the vast sea.The abundant marine resources can provide humans with many raw materials needed for production and life,such as oil,natural gas,and combustible ice.Ships are the main means of transportation for exploring marine resources,and the development of intelligent ships plays a decisive role in human exploration of marine resources.The marine environment is complex and changeable.Ship dynamic positioning technology provides technical support for ship operations and guarantees the safety of ship navigation.So,it is known as the “sacred needle of the sea”in the ocean.Therefore,more and more scholars begin to care about the control of ship dynamic positioning system.However,due to the uncertainty of the ship model and the time delay phenomenon in the propeller system,the control problem of the ship dynamic positioning system is essentially attributed to the control problem of a class of complex nonlinear time delay systems.The current mainstream ship controller design concept is to use state feedback technology.When the measured value of the motion state measurement sensor is contaminated by noise or the sensor fails,then these control algorithms are no longer applicable.Therefore,in order to improve the safety of the ship’s dynamic positioning system,the design problem of the state observer has important practical significance.This paper takes the ship’s nonlinear time-delay system in a complex ocean environment as the research object.At the same time,it uses the advanced Hamilton control theory to design its nonlinear observer for the ship’s dynamic positioning system directly from the perspective of nonlinearity,and gives infinite time and finite time adaptive robust stabilization controller based on observer.The research content of this article is mainly divided into the following three aspects:(1)The infinite-time adaptive robust stabilization control problem of ship dynamic positioning system based on observer is studied.In this paper,when building a three-degree-of-freedom time-delay system with parameters perturbation model,it is necessary to consider the interference of the ship by the marine environment,the parameter perturbation of the model,and the time lag of the propeller system.The three-degree-of-freedom dynamic positioning ship model with time delay and parameters perturbation was transformed into a port-controlled Hamilton model,and its observer system was designed on this basis.Then,using augmented technology and Lyapunov stability theory,several observer-based robust stabilization controllers and observer-based adaptive robust stabilization controllers are designed for dynamic positioning ships with time delays.Compared with the current mainstream nonlinear system approximate linearization technology and error method,this paper has obtained a less conservative result.(2)In order to improve the convergence speed and robustness of ship dynamic positioning system,and further reduce the fuel consumption of ship stabilization operation,this paper studies the adaptive robust stabilization problem of ship dynamic positioning system with time delay based on finite time observer.It is worth pointing out that when studying finite time control problems by applying the Hamilton function method,it is inevitable to use energy shaping technology.However,due to the observer-based method used in this paper,energy shaping technology cannot be applied,which poses a challenging problem for the research of this paper.By using coordinate transformation and orthogonal decomposition methods,the three-degree-of-freedom dynamic positioning ship model with time delay is transformed into a port-controlled Hamilton model,which ingeniously solves the above problems,which is an innovative point of this thesis.On this basis,the finite-time observer system is designed based on Hamilton control theory.Several observer-based finite-time stabilization controllers and observer-based finite-time adaptive robust stabilization controllers are designed for dynamic positioning ships with time-delay using augmented technology and Lyapunov stability theory.Finally,by selecting a suitable energy function,it is proved that the system can be stabilized to the equilibrium point in a finite time.(3)In order to verify the effectiveness of the controller designed in this paper,and promote the close integration of theory and practice.This paper designs a semi-physical simulation model of the ship dynamic positioning control system based on an observer,which realizes the ship’s dynamic positioning function when the ship is not equipped with a speed sensor.First,build the hardware system of the semi-physical simulation model.The semi-physical simulation model is mainly composed of the ship’s main body,main control unit,sensor system and wireless communication module.Secondly,according to the control algorithm of this article,the software part of the ship model dynamic positioning system is designed,and the data communication between the lower computer and the upper computer is realized.Finally,building a simulation platform in the MATLAB environment shows the effectiveness of the algorithm in this paper.In summary,considering the actual situation of ship navigation,this paper designs an observer-based infinite-time robust stabilization controller and an observer-based finite-time stabilization controller for the nonlinear time-delay system of ships based on the mature Hamiltonian control theory.Thereby,the safety and versatility of the ship’s dynamic positioning system are further improved,and a more effective design scheme is provided for the stabilization and control of the ship’s dynamic positioning system.