Research On Fuzzy Control Method Of UUVs Formation

In recent years,the Unmanned Underwater Vehicle(UUV)has played an increasingly important role in the exploitation and utilization of the ocean,the protection of maritime rights and the security of coastal defense.With the advancement of related technologies,the research on UUV is moving in the direction of intelligence,formation coordination,and group autonomy.Using the traditional method to control the UUVs formation,we need to rely on the dynamic and kinematic model.However,UUV works in a complex and variable underwater environment,which is influenced by ocean currents,tides,wind waves,temperature,water depth and various other uncertainty factors.The existing UUV dynamic model can hardly reflect the actual force of UUV.Meanwhile there is some deviation in acquiring UUV information including position,velocity and so on.Therefore,this thesis uses the fuzzy control method for UUVs formation which has high nonlinearity and uncertainty and is difficult to establish the dynamic model.The fuzzy rules are designed based on human understanding of UUV movement.Only at the level of the kinematic model studied the control of UUVs formation.This thesis divides UUVs formation into two processes,formation generation process and formation navigation process.Process of formation includes two basic behaviors: formation generation and obstacle avoidance.Formation navigation includes three basic behaviors: trajectory tracking,formation maintenance and formation transformation.In the process of UUVs formation generation,the formation position allocation method is used to set the target position of each UUV in advance,and a fuzzy controller is designed to control each UUV to reach its respective target position.As for the UUVs formation navigation,navigation points are interpolated and then down sampling to get a series of trajectory points,so the trajectory is tracked by a virtual UUV.A formation control method combining virtual structure and virtual leader is proposed.Formation maintenance and formation transformation are realized by using formation vector,and they are converted to trajectory tracking through generating virtual trajectory,and a fuzzy controller to control the process is designed.Finally,through the distributed control of each basic behavior in the UUVs formation generation and formation navigation,the UUVs formation is controlled.The simulation experiment is designed to verify the feasibility of the formation control method and the rationality of the corresponding fuzzy controller.