Delay Difference Localization Algorithm Research And Implementation Based On Distributed Underwater Acoustic Network

Depending on the difference of the operating mode, distributed acoustic positioning is mainly divided into active and passive positioning. Depending on the difference of the method of positioning, you can select different positioning mathematical models, including spherical positioning mathematical model and hyperbolic positioning mathematical model.No matter what kind of mathematical model is chose, slant range depend on the of product sound speed and propagation time, the target position is estimated by solving nonlinear equations.This article describes three kinds of commonly positioning algorithm by time difference of arrival (TDOA): Chan algorithm, Fang algorithm and Taylor algorithm. In Gauss environment, when the numbers of buoy are three, Fang's algorithm is more accurate among TDOA algorithms. When the numbers of buoy are more than or equal to four,Chan algorithm is better than Fang algorithm .Because Chan algorithm can take advantage of all TDOA measurements provided by hydro-acoustic network , Therefore, Chan reduces the impact of individual large random measurement errors , and achieve better positioning results ;When TDOA measurement error is small, Chan and Taylor two algorithms are close towards the positioning accuracy, but with the increasing time delay difference errors Taylor series algorithm is superior to Chan's algorithm, When Taylor series algorithm better initial value ,Taylor series algorithm has higher positioning accuracy than Chan 's algorithm , but if Taylor algorithm initial choice is not ideal , precision of positioning algorithm will be very bad. This article summarizes a kind of collaborative algorithm based on the above several algorithms When the numbers of positioning are three, the initial value of the Taylor series expansion algorithm obtain by Fang algorithm; When the numbers of positioning are more than three,the initial value of the Taylor series expansion algorithm obtain by Chan algorithm;Collaborative algorithm has higher accuracy than any single algorithm.By derivation and analysis of the positioning error causes, the key factors affecting the positioning system are obtained. The key factors include delay estimation error of acoustic positioning system, positioning itself, positioning error caused by GPS positioning system,positioning error caused by underwater acoustic multipath channel, positioning error caused by velocity measurement and the impact of target motion. Analysis each point of the whole region positioning accuracy and reduce error. Calculate delay difference with equivalent sound speed profile. In the positioning area, positioning accuracy in the center is highest and position error is small. Position error is greater with the farther distance from the central region. Combining with the technical performance of the current situation and the target position system, underwater acoustic positioning algorithm is designed and verified. Under the Matlab environment, I realized Chan algorithm, Fang TDOA algorithm and Taylor distributed algorithms and improved the position algorithm.