Research On Cooperative Formation Control Strategies Of Unmanned Surface Vehicles

As an effective tool for the exploration and development of ocean,unmanned surface vehicles(USVs)are widely used in civil and military fields,such as underwater surveying and mapping,environmental monitoring,security patrols,searching and rescuing,and scientific research exploration.Notice that,limited equipments can be loaded in a single USV,and these equipments can not meet the needs of complex tasks.However,the capacity limitation of single USV will be overcome by cooperation of multiple USVs.Meanwhile,the collaborative system composed of multiple USVs has stronger robustness,communication capability,mobility,flexibility.This thesis focuses on the research of the cooperative control of USV formation,and the main contents are as follows:1.A 3-degree-of-freedom(sway,yaw,row)motion model is established for USV systems subject to disturbances induced by wind and waves,and the interference forces and moments,which are induced by wind and waves,on hull are analyzed in detail.Note that,this thesis mainly studies the cooperative control of USV formation.In the process of cooperative control,it is necessary to constantly exchange position information and speed information of each USV.Thus,based on the established 3-degree-of-freedom(sway,yaw,row)motion model,a state vector,which contains position variables and velocity variables,is constructed.Then,a mathematical model,which is suitable for the coordinated control of USV formation systems,is derived.2.The output consensus problem of networked USV formation systems is studied.First,a 3-degree-of-freedom motion model is established for USV systems.Second,based on the motion model,an incremental state observer and an incremental predictive controller are constructed to investigate the effects of network-induced delays and packet dropouts on the systems under study.Third,a novel incremental predictive control scheme is developed to ensure that the outputs of all USVs in the formation reach consensus asymptotically.Finally,an illustrative example is given to verify the effectiveness of the proposed incremental predictive control scheme for networked USV formation systems.3.The problem of cooperative formation control of unmanned surface vehicles is investigated.According to the second-order consensus protocol with a virtual-leader,a distributed control law is derived,in which the consensus formation motion information can only be obtained by a part of USVs.Taking advantages of the shared information between adjacent multi-USVs,the USVs can control self-motion trajectory in a concerted cooperation way.Meanwhile,they can also follow the virtual-leader movement along a desired route.The error function is defined and the stability of the system is proved based on the Lyapunov stability principle.Simulation results are presented and discussed for validating the proposed control strategy.4.The problem of path tracking control of USV formation systems is studied.To make the formation move along a desired path,a network-based predictive control scheme,in which the network-induced delays and packet dropouts are taken into consideration,is proposed.Based on the estabilished model,a corresponding stability analysis is given.According to the numerical analysis,one can conclude that,under the action of the proposed control scheme,the negative influences of network induced delays and packet dropouts can be compensated effectively.In addition,the USV formation will move along a desired path.