A Study On Underwater Terrain Matching Aided Navigation Technology Of AUV

Underwater terrain matching navigation (UTMN) is an independent and all-weathernavigation mode using terrain matching technology to gain precise positioning of underwater,which plays an important role on the navigation of underwater vehicle for long period of timesubmerged. For the precise navigational positioning of Automous underwater vehicle (AUV),with multibeam echo sounder (MBES) as the measuring means, underwater terrain matchingnavigational positioning method is thoroughly investigated with real sea test data. The mainwork is as follows:(1) The principle, model and suitable method of UTMN are investigated. Thecomposition of UTMN system is probed into in theory, which is divided into basic navigationunit, depth measuring unit and terrain matching unit. According to which, the principle ofUTMN is analysed. The model of UTMN is analysed, including state space model and digitalterrain model, follow which the factors influence the performance of terrain matchingnavigation are educed. The difference between land and underwater terrain navigation iscompared, from which the advantage of using MBES for UTMN is discussed, and the methodsuitable for UTMN with MBES are analysed in theory.(2) The method for modeling of local high-accuracy underwater digital terrain isinvestigated. The composition and principle of MBES measuring system is introduced andthe parameter of the MBES used in this paper is presentd. The principle of post-processing ofMBES data is analysed and the flow of it is presented. Aim at the filtering of MBES data, asingle ping filtering based on dynamic clustering is proposed. After space homing and gridingare applied to the filtered data, the local high-accuracy underwater digital terrain model(UDTM) is made.(3) The real-time characteristics extraction and construction of matching unit ofunderwater are investigated. Real-time underwater terrain matching model of single beamand multibeam are established, and a beam selection mode for multi measuring beams basedon adaptive of terrain characteristic is proposed. For the interpolation of terrain, on theanalysis of terrain interpolation model, a bilinear method based on fractal compensation isproposed, which has good adaptability for different terrain characteristic. For the improvement of interpolation accuracy and efficiency, a method for storage of large terrainbased on mixing resolution is proposed, form which a fast interpolation strategy based onindex is proposed. The interpolation time decreases rapidly.(4) The terrain matching positioning method based on correlation is investigated. Basedon the correlation principle and the surface terrain characteristic get by multibeam echosounder, a method based on maximal likelihood estimation (MLE) is proposed for underwaterterrain matching positioning. The UTMN model for MLE is presented, for the false peaks interrain matching, a method based on Fischer criterion is proposed for false peak elimination,which is effective for the false peak elimination appeard in the terrain matching. Positioningtest based on MLE with real MBES data is carried out.(5) The UTMN of AUV bsed on information fusion is investigated. From the perspectiveof information fusion, the terrain matching technology is integrated with the basic navigationsystem, the association model of terrain matching navigation and the validity flow of terrainmatching positioning with nearest neighbour (NN) are presented, from which a continuousnavigational positioning mode base on association reliability is proposed. The UTMN modelbased on Bayes estimation is presented and particle filter is used for near optimal resolvationof Bayes estimation problem, and an improved particle filter is proposed for path tracking ofunderwaer terrain matching. The factors that influence the UTMN accuracy are analysed. Atlast, the UTMN system construction of AUV is presented from the modularization view. Forthe UTMN of AUV, a navigation strategy with two models is proposed and simulations arecarried out with MBES data.This paper investigated the principle, method and implementation steps of UTMN ofAUV, and the play back mode simulation is carried out with real MBES data. The resultsshow that the method proposed in this paper has good accuracy and adaptability for terraincharacteristic, which can be used for position correction of underwater navigation for longperiod of time submerged. The proposed method is proved effective, reliable and practical.