AUV Cooperative Navigation Method Based On Nonlinear Filtering

Autonomous underwater vehicle(AUV)is an important tool for Human's development of the marine environment.With the deepening of exploration activities,the application of a single AUV can no longer meet the actual requirements.Multi-AUVs cooperation which has many advantages in underwater navigation has obtained more and more attention.Due to the complex and ever-changing underwater environment,the high-precision navigation of multi-AUVs is the most important issue to be solved urgently.In this paper,nonlinear filter method,which fully considers the limited conditions of underwater navigation,has been studied for autonomous underwater vehicle co-navigation technology.Firstly,the technical challenges faced by AUV cooperative navigation algorithms have been analyzed.A reasonable cooperative navigation scheme based on the limited conditions of high-precision cooperative navigation has been proposed,including the modeling of multi-AUV collaborative navigation system,the observability of the system model Analysis,the AUV co-navigation structure,communication,etc.,to lay the foundation for the following AUV collaborative navigation technology.Then,this paper studies the AUV cooperative navigation method based on distributed nonlinear Kalman filter.Due to the disadvantages of centralized processing,which can not be applied in real time,has huge amount of calculation and poor fault tolerance,AUV navigation method based on distributed structure is proposed.Under the ideal condition of communication,cooperative navigation method based on Extended Kalman filter(EKF)and Unscented Kalman Filter(UKF)is proposed aiming at the AUV nonlinear system,and the two methods are compared and analyzed by simulation.Then,the AUV collaborative navigation method based on distributed nonlinear information filtering has been explored.Considering the serious delay of co-navigation and the limitation of communication bandwidth under the complex underwater environment,this dissertation applies information filtering with unique advantages in distributed structure,and proposes a distributed non-linear information filtering method for AUV collaborative navigation.Firstly,Extended Information Filter(EIF)and Unscented Information Filter(UIF)are derived in detail.Based on these methods,the key steps of AUV cooperative navigation based on EIF and UIF are given.These methods use the advantages of Information Filter(IF)which has simple structure and can be decoupled easily.They retain the key historical information of high precision AUV in information vector and information matrix,and transmits the key historical information asynchronously.The methods fully consider the problem of communication delay and minimizes the channel bandwidth limitation,and tracks the information correlation between sever-client AUVs in low-precision AUV filtering algorithm,which meets the practical application conditions of cooperative navigation.Afterwards,based on the distributed EIF and UIF,the simulation is carried out to verify the superiority of the proposed cooperative navigation algorithm.Finally,aiming at the abnormal noise interference in underwater communication,AUV co-navigation method based on robust UIF has been proposed.Considering the serious influence of exceptional measurement noise on the state estimation of information filtering in underwater environment,this paper applies the M estimation method to deal with the abnormal noise problem,The key steps of collaborative navigation method based on robust UIF are given.By setting reasonable simulation conditions and adding noise outliers,the reliability of the proposed robust information filter is verified.