Research On Cooperative Localization Method For Multiple UUVs

This thesis aims to solve the problem that UUVs with poor navigation ability cannot effectively self-position themselves in response to the needs of multi-UUV underwater cooperative operation.On this basis,it aims to improve the positioning accuracy of multiUUV cooperative formations for underwater targets.Firstly,the research on the multi-UUV cooperative navigation and positioning method is completed.Taking the single-pilot master-slave structure as the research object,the basic principle of multi-UUV cooperative navigation and positioning is analyzed,and the UUV kinematic model and measurement model are established.Design an EKF cooperative navigation and positioning algorithm based on the standard Kalman filter algorithm.Then,considering the constraints of underwater acoustic communication,the EKF algorithm is improved based on state compensation,that is,the DEKF algorithm.The EKF was compared with the dead reckoning,the simulation results showed that the average value of the EKF positioning error was smaller than that of the dead reckoning,which could effectively correct the UUV’s own positioning error;The EKF and DEKF were compared and analyzed,and the simulation results showed that DEKF can effectively compensate the system state estimation error under the communication delay,and the positioning accuracy is improved compared with the EKF algorithm.Secondly,based on the research on multi-UUV cooperative navigation and positioning,the research on underwater target positioning method is carried out.First of all,the signal receiving model of the hydrophone array mounted on UUV is established by taking the uniform linear and circular array as an example.Taking linear array azimuth estimation as an example,the performance of conventional beamforming azimuth estimation and MUSIC algorithm are compared,and it is concluded that MUSIC can distinguish the target azimuth more clearly than conventional beamforming.Then,a multi-UUV cooperative detection system is designed,and each UUV is regarded as a node,and the underwater single-node DOA estimation is carried out based on MUSIC.Next,the formation mode of multi-UUV cooperative detection is studied,and two typical unobservable paths that should be avoided in the process of multi-UUV cooperative detection are obtained.In the end,the multi-UUV node co-location algorithm is designed,and the simulation experiment is carried out.The simulation results show that selecting the appropriate formation and signal-to-noise ratio can effectively improve the target positioning accuracy.Finally,the cooperative positioning lake test is carried out to verify the cooperative navigation and target positioning method.Using the test ship to simulate UUV,the collaborative test platform is first built,and then the collaborative positioning test plan is designed,and the test is carried out according to the experimental steps.The test shows that the system can correct the positioning error of the slave ship carrying low-precision navigation equipment through the DEKF cooperative navigation and positioning algorithm,and improve the self-positioning accuracy of the slave ship;the multi-node cooperative positioning algorithm can effectively locate the fixed-point target.