Research On High-precision DVL System Design And Performance Simulation Modeling

Doppler Velocity Log(DVL)is a marine equipment for speed measurement and logging based on the Doppler effect.It plays a vital role in the navigation of unmanned underwater vehicles.With the rapid development of unmanned underwater vehicle technology and the continuous expansion of application scenarios,the accuracy requirements for underwater navigation are increasing,and the speed measurement accuracy of DVL is the decisive factor for its navigation performance.Therefore,high-precision DVL technology research is needed.On the basis of studying the existing DVL technology at home and abroad,this paper studies and analyzes the transmitted signal and DVL algorithm that affect the accuracy of DVL Doppler velocity measurement,and then designs and implements a high-precision DVL system.During the development of the high-precision DVL system,in order to effectively carry out the measurement accuracy performance verification,this paper also proposed an optimized seabed and stratospheric echo model,and based on this design and realized an echo used to verify the performance of the DVL Data simulator.During the development of the high-precision DVL system,in order to effectively carry out the measurement accuracy performance verification,this paper also proposed an optimized seabed and stratospheric echo model,and based on this design and realized an echo used to verify the performance of the DVL Data simulator.The specific research content and research results of this article are as follows:1.In-depth research has been conducted on the factors affecting the accuracy of DVL Doppler velocity measurement.Analyze and research factors such as the speed of sound change,installation form,and unstable motion of the aircraft that cause the DVL accuracy error,and reduce the error by real-time calculation of sound speed,compensation of installation error,design of Janus formation structure and collocation of attitude sensors.2.The transmitted signal of DVL is researched and analyzed.Time-frequency analysis of CW single-frequency rectangular pulse,LFM,HFM,two-phase pseudo-random coding and other transmission signal forms,among which CW signal and m-sequence coding signal are suitable for the transmission signal of DVL system;According to the research conclusions,the waveform design is carried out for the narrowband and broadband transmission signals of the high-precision DVL system.3.The echo signal of DVL is modeled and analyzed.When the DVL can detect the seabed,this paper constructs a seabed echo optimization model based on the scattering theory based on the fan ring seabed echo model.This optimization model is compared and analyzed with the traditional model.Compared with the traditional model,the optimization model has a smaller envelope characteristic error with the real seabed echo,especially the envelope characteristic of the broadband echo is reduced by more than 20%.4.The high-precision DVL algorithm is simulated.Based on the research of complex autocorrelation algorithm,the bottom tracking and convection tracking algorithms are designed.Aiming at the problem of ambiguity in velocity measurement,defuzzification schemes such as broadband autocorrelation and narrowband Fourier transform are proposed.Through data analysis,for the Doppler velocity measurement system that transmits narrowband signals and broadband signals,the velocity measurement error is not more than 0.2%.5.The high-precision DVL system scheme design was carried out.The high-precision DVL signal flow is designed.Designed the key modules in the signal processing module(quadrature demodulation,filtering,downsampling,uPP communication module on the FPGA side and uPP signal reception on the DSP side,seafloor ranging,bottom velocity measurement,and tropospheric velocity measurement modules)And realize,and carry on the programming realization on the actual signal processing board.6.The performance verification of the high-precision DVL system was carried out.The simulator designed by optimized seabed and stratospheric echo models sends narrowband and broadband echo data respectively.In the bottom tracking mode,the velocity measurement error is0.1490% and 0.1200%;in the convection tracking mode,the velocity measurement error They are0.2893% and 0.2218% respectively.