Research On Coordinated Formation Control Methods For Multiple Dynamic Positioning Ships

With the development and use for the marine nature resources,the serve area has already progress gradually from the neritic area to the abyssalpelagic areas.So the request about the efficiency for the marine operations and the automation degree for developing to the ocean resources is higher.Though the development of dynamic positioning for single ship is quick,after all,the operational ability of single ship is limited.the operational time of single ship is shorter for the restriction of energy.Therefore,the complicated task is achieved by coordinating multiple ships to work collectively in practical applications.Furthermore,compared to the single ship,the coordination formation of multiple ships has many latent advantages as following.They will cover higher operational efficiency,better fault-tolerant property and stronger robustness.Consequently,the research on coordinated formation control of multiple ships has important practical application value.This thesis focuses on this topic,the coordinated formation control method for multiple ships and the robust coordinated formation control method for multiple ships which with the external disturbances are researched.The highlights of the thesis are as following.Firstly,for the coordinated formation control of multiple ships with disturbances-free,a passive coordinated formation control algorithm based on the virtual leader strategy is proposed using the passive synchronization control theory.The proposed coordinated control algorithm is designed based on the guidance-control structure.The guidance system is achieved by simulating the virtual ship and designing the controller for the corresponding operation.And then the desired position and velocity information for coordination operations of multiple ships is given.The control system is achieved by designing the universal coordinated formation controller for each operational mode of ships using the passive synchronization theory.The control force input of different operational mode is achieved through the desired information form the guidance system.Then multiple ships can form the desired formation and perform the operations collectively.Furthermore,the asymptotic stability of the whole system is analyzed using the Matrosov theorem.The simulation is carried out,and it validates the effectiveness of the proposed algorithm.The coordination operations are performed in different operational mode and the whole communication of the group of ships is needless.Secondly,for the coordinated formation control of multiple ships with the general directed unbalance communication topology,a passive coordinated formation control algorithm under the directed communication topology is proposed for multiple ships using the passivity theory.Based on the above passive coordinated formation control algorithm based on the virtual leader strategy,the control force input of the proposed algorithm is divided into two parts:the equivalent force and the coordination force.And the control input is designed using the passivity theory.Combined with the property of the directed strong connected graph,the asymptotic stability of the whole system is analyzed based on the Lyapunov stability theory.Besides,the coordinated formation controllers under the directed communication topology are designed for coordinated dynamic positioning,coordinated trajectory tracking and coordinated formation of multiple ships,respectively.And the smooth switch between different operational modes is achieved based on the hybrid system theory to satisfy the request of practical applications.Last the effectiveness of the proposed coordinated formation algorithm and the hybrid coordinated formation under multiple operational modes is validated by the simulation results.Thirdly,for the coordinated formation control of multiple ships which is in presence of the unknown constant current disturbances,a robust coordinated formation control algorithm based on the virtual leader is proposed for multiple ships using the adaptive backstepping method.In order to achieve the robust coordinated formation control,the desired position information of each ship is given by the virtual ship as the leader for the whole formation.The nonlinear controller is designed for each ship using the backstepping to guarantee these ships to form the desired formation and perform the operation collectively.Furthermore,the backstepping controller is redesigned using the adaptive control aiming at the unknown constant disturbance.The coordinated formation control is also achieved under the current disturbance by estimating the unknown disturbance.The asymptotic stability of the whole system is analyzed based on the Lyapunov stability theory.And the effectiveness of the proposed robust coordinated formation algorithm is validated by the simulation results.Lastly,for the coordinated formation control of multiple ships which is in presence of the time-varying marine environment disturbances,a robust coordinated formation control algorithm is proposed for multiple ships by combining the cross-coupling synchronization control with the backstepping sliding mode control.The proposed coordinated formation controller is designed using the cross-coupling synchronization control technology.In order to maintain the better coordination performance for multiple ships with the time-varying disturbances,the cross-coupling synchronization control is improved to accommodate the backstepping sliding mode control.Then the coordinated formation control algorithm is achieved to compensate the time-varying disturbances.The coordinated control is accomplished by defining the cross-coupling error between these ships and eliminating the mutual synchronization error.So this algorithm can be the same with the leaderless coordinated formation control.That is,all the ships are equal,and any ship doesn't need to be emphasized which ship is more important.Besides,the asymptotic stability of the whole system is analyzed based on the Lyapunov stability theory and the notation of graph.And the effectiveness of the proposed robust coordinated formation algorithm is validated by the simulation results.