| Multi-beam Sounding system plays an important role in national marine economic development and marine topographic survey,and high precision attitude is the guarantee of multi-beam high precision measurement.In actual measurement,wind,wave,ship speed variation and other factors will affect the attitude of Inertial navigation system(INS).In order to improve the accuracy of INS attitude,GNSS attitude is often used to assist.Therefore,it is of practical significance to study the influence of GNSS attitude measurement error.In this paper,the application of multi-antenna GNSS/INS combined attitude measurement in multi-beam bathymetry is studied.The main contents include GNSS attitude measurement principle,GNSS attitude measurement error analysis,four-antenna attitude measurement experiment,GNSS/INS combined attitude filtering algorithm research and GNSS/INS attitude measurement software development.The main research contents and results are as follows:(1)Based on the geometrical model of GNSS attitude measurement,the influence of baseline length and included angle on GNSS attitude measurement error is simulated and analyzed.The experiment of attitude measurement with four antennas at sea is designed.The ship attitude is calculated by using the direct attitude calculation method,the LS method and the TLS method respectively,and the results are compared with those of the high-precision HYDRINS inertial navigation system.(2)The precision error model of GNSS positioning,attitude determination and multi-beam bathymetry is constructed,and the numerical solution of nonlinear equation is realized by Newton iteration method.According to the precision requirements of GB12327-1998 Hydrographic Code and other related specifications,the error relations among GNSS positioning,attitude determination and multi-beam bathymetry are analyzed and summarized through simulation experiments.(3)Aiming at the obvious gross errors in attitude information of inertial navigation system when ships are accelerated,the gross errors removal ability of conventional Kalman filter,extended Kalman filter and robust Kalman filter of M estimation are analyzed experimentally,and Validity of the three algorithms applied to GNSS/INS loose combination attitude determination is verified.(4)GNSS/INS integrated attitude determination software is developed based on MFC framework of VS2012 platform.The software can process GNSS data with different location calculation modes.The experimental analysis is carried out based on the measured data.The accuracy of baseline calculation of attitude determination software is verified by comparing with NovAtel-IE commercial software.The experimental results show that the attitude calculation of GNSS/INS integrated attitude determination software can meet the requirements of hydrographic specification in PPK mode. |
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