Research On Positioning Method Of Marine Coordinate Measuring System

For "digital,intelligent,and fine" shipbuilding,the acquisition of high-precision3 D coordinate information at key points is a vital part of ensuring the ship construction accuracy,which plays an important role in the stages of compartment closure,berth outfitting and dock outfitting,etc.However,due to the poor environment and numerous interference sources of the ship construction site,it is difficult for traditional positioning methods to obtain high-precision 3D coordinate information under this condition,which seriously affects the accuracy of ship construction.Therefore,it is of great significance to carry out the 3D information measurement and positioning method research under the disturbance environment which is suitable for ship construction site in improving the ship construction technology level,ensuring the construction quality,and reducing the construction period.This topic "Research on Positioning Method of Marine Coordinate Measuring System" focuses on the requirements of ship construction measurement and positioning tasks in a complex interference environment,aiming at the three typical construction stages of cabin closure,berth outfitting,and dock outfitting,based on the laser scanning network measurement and positioning system,though studying the positioning error characteristics of the system at different stages,at last proposes the measurement and positioning methods suitable for different construction stages.This topic breaks through a series of key technologies such as the integrated rapid calibration method,anti-random vibration interference positioning method and anti-ship sway interference positioning method,and achieves high-efficiency and high-precision positioning under complex environmental interference at last.The main research content of the paper is as follows:At first,a positioning scheme is designed for the marine coordinate measuring system,and the principle of beam adjustment is studied.Based on the principle,the positioning error distribution law of this method under the condition of no interference is analyzed.Then the interference conditions of different construction stages are analyzed and quantified,and the positioning error characteristics of the positioning method based on the principle of beam adjustment under different interference conditions are theoretically studied.The simulation experiment results show that,random vibration interference during the closing phase of the cabin will cause random fluctuations in the positioning results;Continuous vibration interference during the berth outfitting phase will cause the parameters of the transmitter to change;The hull sway interference in the dock outfitting stage will cause periodic changes in the positioning results;As a result,the positioning error increases to different degrees compared with the condition without interference.Secondly,to solve the problems of complex calibration methods and low calibration efficiency for transmitter,an integrated calibration method for transmitter parameters is proposed.By studying the principle of parameter calibration of the transmitter,the quantitative relationship between the constraint conditions and the calibration parameters is determined.On this basis,the calibration methods based on the distance constraint and the position constraint are respectively proposed,which realizes the integrated calibration of the parameters of the transmitter;The calibration parameters can be solved quickly based on the Levenberg-Marquardt calibration algorithm.The results of simulation experiments show that the two proposed calibration methods can achieve the integrated calibration of transmitter parameters.The calibration method based on position constraint has higher calibration accuracy than the calibration method based on distance constraint,and it guarantees the accuracy of parameter calibration compared with the traditional method,which verifies the effectiveness of the proposed integrated calibration method for transmitter parameters.Thirdly,in view of the problem that marine coordinate measuring system is easily affected by the random vibration in the cabin closing stage which causes a low positioning accuracy,a positioning method against random vibration interference is proposed.A positioning model based on factor graphs is constructed,and the specific implementation methods of key nodes in the positioning model are studied.On this basis,a weight function equation is set up to deal with the random vibration interference,and a high-precision positioning of the proposed method is realized.The positioning effect of the proposed method is theoretically analyzed.The simulation experiment results show that under the condition of random vibration interference,the proposed positioning method reduces the positioning error by 27% compared with the traditional positioning method,which verifies the effectiveness of the anti-random vibration interference positioning method.Fourthly,in order to solve the problem that the marine coordinate measuring system cannot accurately measure and position under the condition of hull sway interference,an anti-hull sway interference positioning method based on inertial navigation system is proposed.A fast calibration method of coordinate system based on fixed-axis rotation is designed,which realizes the fast calibration of the coordinate system of the transmitter and the coordinate system of the inertial navigation system;By continuously reconstructing the relative pose relationship between the coordinate systems,the point to be measured is realized in the navigation coordinate system;Software and hardware synchronization schemes are designed to ensure the time synchronization of the two systems.The simulation experiment results show that the positioning error of the proposed positioning method reached 0.76 mm under the condition of hull rolling interference,which verifies the effectiveness of the proposed positioning method.Finally,in order to verify the actual performance of the methods proposed in this paper,the principle prototype of the marine coordinate measuring system has been built to carry out the transmitter parameter calibration method verification experiment,the anti-random vibration interference positioning method verification experiment,and the anti-ship sway interference positioning method verification experiment.The experimental results show that,compared with the traditional calibration method,the proposed locationconstrained transmitter parameter integrated rapid calibration method has a higher calibration efficiency under the condition of similar calibration accuracy;Compared with the traditional positioning method,the positioning error of the proposed anti-random vibration interference positioning method is reduced by 24%,and the distance measurement error of the proposed anti-ship-swaying positioning method is reduced by 53%.