Underwater AUV Short Baseline Positioning Technology Based On GPS Buoy

In recent years,With the development of underwater acoustic communication technology,underwater positioning technology has achieved gratifying research results.In the South-to-North Water Diversion Project,the aqueduct used to transport water is a large and unique thin-walled concrete structure,which will cause cracks due to the influence of various factors,causing the aqueduct to leak during the water transport process,which seriously affects the aqueduct The normal use function and economic benefits.In order to detect the coordinates of possible cracks in the underwater aqueduct,based on the underwater acoustic communication technology,this paper designs a GPS buoy-based underwater AUV short-baseline positioning system,and completes the system construction and testing in the pool.The specific work content is as follows:(1)Positioning system scheme design.A positioning matrix composed of 4 surface buoys with GPS function is designed.The surface buoy is connected with four hydrophones,and the positioning of its position is completed through GPS global satellite navigation.The hydrophone is used to receive the underwater acoustic signal emitted by the transducer installed on the AUV and estimate the position of the underwater AUV.Finally,the data center of the system converts the calculated position into the geodetic coordinate system to complete the crack detection.(2)Research on time delay estimation algorithm.Signal attenuation,multipath effects,and noise in the underwater environment can interfere with the normal transmission of signals and cause errors in signal delay estimation.This paper analyzes and compares the pros and cons of several weighted delay estimation algorithms,and finally chooses PATH-weighted generalized cross-correlation delay estimation as the system's timing algorithm.(3)Research on underwater acoustic positioning algorithm.Aiming at the characteristic that the speed of sound waves does not change much when propagating in shallow water,a total least square underwater positioning algorithm based on Taylor series expansion is proposed.First,on the basis of the least squares algorithm,the augmented matrix of the error vector in the positioning equation is constructed,and the singular value decomposition is performed on it to obtain the coordinates of the underwater AUV.The purpose is to reduce the error caused by the matrix disturbance tothe positioning result.Secondly,iteratively optimize the results by using Taylor series expansion algorithm.Finally,the performance of the algorithm is simulated.The results show that compared with the least squares algorithm,the algorithm proposed in this paper is less affected by the environment,has strong stability and better real-time performance.And the accuracy is significantly improved compared with the least square algorithm.(4)Pool and lake test experiment.An experimental platform for the pool was built and experiment simulations such as time measurement analysis,signal transmission attenuation analysis,positioning accuracy analysis,and array layout structure analysis were carried out.A method of eliminating outliers in positioning is proposed,which reduces the influence of inaccurate time delay estimation on positioning.Finally,a lake test experiment was carried out to verify the feasibility of the system in the project.