Cooperative Localization Of Moving Long Baseline Based On Multiple Unmanned Surface Vehicles

With the development of automation technology,sensor technology,power and energy technology,Autonomous Underwater Vehicle(AUV)with perceived and be-havioral abilities has been paid more and more attention in the field of military and civil affairs.Good localization capability is the key to achieve underwater tasks suc-cessfully.Due to the complexity and particularity of the marine environment,there is no underwater positioning system can be comparable with GPS.The underwater acoustic positioning is the main method for high accuracy positioning of AUV.Moving long baseline system is a kind of underwater acoustic positioning technology with long time,large scale and high precision.This paper focuses on the cooperative localiza-tion of moving long baseline based on multiple Unmanned Surface Vehicles(USVs).The study includes the optimal configuration of USVs,influence of system parame-ters on positioning accuracy,the model and algorithm of cooperative localization with unknown sound speed,simultaneously velocity and position estimation of AUV.The main contents of this dissertation are interpreted as below.(1)To study the moving long baseline(MLBL)positioning algorithm based on the distance measurement.According to the Kinematic model of AUV and distance measurement between AUV and USV,the positioning model of MLBL is established.By using the optimal estimation theory,the least squares(LS)and Kalman filter(KF)algorithms are analyzed.On the basis of making full use of distance measurement information,the moving horizon estimation(MHE)algorithm is proposed.Simulation results compare the positioning accuracy of these three algorithms.(2)To study the optimal configuration of USVs.With considering the noises of the position measurement of the USV and the distance measurement between the USV and AUV,we re-designed the positioning accuracy evaluation function according to the optimal estimation theory.By minimizing this evaluation function,we get the optimal configuration of USVs:optimal formation of USVs,optimal distance between AUV and USV.Simulation results verify the rationality of the optimal configuration of USVs.(3)To study the influence of system parameters on positioning accuracy.Accord-ing to the positioning accuracy evaluation function,we get the factors that affect the positioning accuracy.In the case of optimal formation,the influence of the system parameters on the positioning accuracy is analyzed,such as the number of US Vs,the depth of AUV and the parameter of distance measurement error.The relationship between the parameter of distance measurement error and the optimal distance is deduced.Simulation results verify the correctness of the theoretical analysis.(4)To study the model and algorithm of cooperative localization with unknown sound speed.Based on the distance measurement model,we establish the cooperative localization model with unknown sound speed.By analyzing the sound speed profile(SSP)model,the simplified positioning model of MLBL is obtained.The existence conditions of the position solution is analyzed.The ULS-based unscented Kalman filter(UKF)algorithm is proposed.The simulation results show that the proposed algorithm can effectively improve the positioning accuracy.(5)To study the simultaneously velocity and position estimation of AUV.In the case of unknown velocity of AUV,we propose a method to simultaneously estimate the velocity and position of AUV.According to the positioning model of MLBL,a linear/nonlinear hybrid system is established.In this system,we decompose the input and the state of the system,and propose a simultaneously input and state estimation algorithm.Simulation results verify the effectiveness of the proposed algorithm.