| The long baseline positioning system(LBL),for its sound positioning performance,is widely utilized in such high-precision work as target positioning,structure installation,and damage detection.In underwater target positioning,as LBL is mainly used to track the target position in a real-time and exact manner,high-precision calculation has been focused on.In practical engineering projects,as the last component,the software platform need calculate basic positioning,addressing such problems as multi-path effect,range ambiguity,and sound speed error.In such context,this thesis,from the software perspective,focuses on design and achievement of the positioning method,correction technology,and display and control software on upper computer in a practical engineering project.The thesis compared both basic geometric localization methods and optimized ones which make use of redundant measurements.The former included spherical intersection and hyperbolical intersection,and for the later we mainly discussed linear least square method and Gauss-Newton iteration method.Next we analyzed the factors influencing the localization result such as time measurement,array calibration and sound speed error.In order to show the quantitative result,we simulated the positioning error for the whole detection coverage in the condition of different factors.For sound speed error,the thesis compares several typical theories and proposes ray-tracing method according to their simulations.Based on the simulation,we adopted buoy long baseline system(GPS Intelligent Buoy Systems,GIB)to reduce the array calibration and confirm the array position in real-time,synchronous clock used to get one-way sound propagation time between target and receiver.After that,apart from effective signal process the LBL system we promoted ‘Three Pulses Coding Signal with Frequency Hopping’ in order to add new criterion to a common expert system for multi-path effect restraint as well as lessen the maximum number of cycles for range ambiguity.Finally we introduced Kalman Filter to realize further correction.The software is implemented by CVI/labwindows.We tried to modularize the design and use interface to complete the data transfer.The main mission of the software includes the control of hardware system,the serial port communication between hardware and software,the network data upload to control center,target position calculation and modification,target route display and data storage in the computer.As option we allowed the user to choose the way of sound speed correction.And an array of optional components can be set up for working area of different size,especially for 4 components the user can choose which component is needed.Also the software offered some auxiliary functions such as graph zooming.Multithread technology and Active X played important roles in the software development,realizing the interaction response between user and surface,communication in real-time and calculation at the same time.According to the test result,the LBL software achieved all of the requirements,gave results within acceptable error range and kept operating in good state,which can be applied to engineering. |
