Research On Coordinated Synchronization Control Of Multiple DP Ship Based On Event Trigger

With the exploration and development of marine resources and the continuous improvement of the requirements of the ship at sea. Which makes the technology of dynamic position has been developed rapidly. Multiple DPs can through the coordination between individuals together to complete a complex task, so the study of multiple DPs have a certain practical application value. However, the traditional multi-ship control strategy is based on the time planning strategy, and the resource consumption of this control strategy is relatively large, the propeller of the mechanical wear is also large. Therefore, this paper puts forward a control strategy based on event triggered, this control strategy executed only at necessary time not at periodic. But this control strategy could deal with unexpected situations in time. In this paper as the research object of multiple dynamic positioning ships, the control strategy of event triggered, respectively, centralized control and distributed control are analyzed, and when communication blocked ,this paper use the method of switch the communication topology graph to describe it and proved that the event-triggered control strategy can also achieve multiple DPs synchronous when the communication is blocked ..The main research content of this paper is as follows:Firstly, two kinds of coordinate system, which is needed by the mathematical model of the three degree of freedom motion of the ship, is established. And then based on the general expression of the Euler Lagrange system, establish the mathematical model of the three degree of freedom motion of the ship and the disturbance force(wind,wave and current). And the model is verified by simulation.Secondly, design the control system structure of multi DPs' event-triggered;select the trigger condition, and design the control flow. Using the method of switching the communication topology to describe the situation of maritime communications blocked.Thirdly, considering the reduction of propeller wear and tear, and increase the life of the propeller saving resources., use the idea of leader-follower, and the use the centralized control and distributed control strategies respectively, based on Lyapunov stability theorem to derive the nonlinear controller. Where used the two kinds of control strategy , centralized control and distributed control , desigh the global trigger function and local trigger function. The synchronous control of multiple DPs are realized. In order to avoid the event triggered systems in finite time triggered an infinitely large number of times, namely zeno behavior. In this paper, are given to demonstrate to assure the zeno behavior does not exist. The simulation experiments confirm that the event triggered control method can realize the synchronous motion of the multi vessel. At the same time, proved through analysis and simulation verification, the effect of distributed control is better than the effect of the centralized control.The communication topology of dynamic positioning ships in local event triggered control strategy under the trigger times were significantly less than that of the global control.And then taking into account the communication between the ships are blocked, etc. the DPs can not receive and send information. In the view of this situation, do a simulation for switching communication topologies of ships synchronous control. It is proved that in communication is blocked, the event triggered control still can realize the synchronous control of multiple ships.Finally, the research results of this paper summarized. And discuss the deficiencies of the paper and the need to improve.