Research On Detection Method Of Pipline And Characteristic Position Based On Inertial Navigation

Pipeline transportation is widely used in the transportation of flammable,explosive and toxic substances such as oil and gas due to its economic,fast and reliable properties.In the process of pipeline transportation,due to the influence of natural environment,human factors,material corrosion and other factors,there will be corrosion,cracks,oil stealing holes and other defects.Therefore,the regular detection of the pipeline,and its integrity analysis is the guarantee of the safe and stable operation of the pipeline,has an important role in preventing the occurrence of major accidents.The pipeline geographic coordinate positioning system based on inertial navigation technology can be carried on the pipeline detector and work at the same time.Combined with the defect detection function of the pipeline detector,the pipeline defect and feature position can be accurately located.In the off-line solution process of pipeline inertial mapping,the measurement data can not only solve the trajectory of the whole pipeline,but also contain a lot of valuable information waiting to be mined.This paper studies the basic theory of inertial navigation and the principle and related algorithm of pipeline geographic coordinate inertial mapping based on strapdown inertial navigation technology,studies the data offline solution preprocessing process,and on this basis,deduces the attitude correction model and inertial navigation system speed correction model combined with odometer and positioning point information,and gives the correction method.The external positioning points are introduced to correct the track error of pipeline geographic coordinates.Two methods of trajectory error correction for pipeline geographic coordinate inertial surveying and mapping are proposed,which are suitable for different engineering practice.The first method is the fast solution method.The linear correction principle of longitude and latitude error is used to correct the trajectory,and the bidirectional linear correction is used to eliminate the mutation of the trajectory at the positioning point.The second method is the pose and velocity correction method of the inertial navigation system in which the three-axis error of the geographic coordinate system at the positioning point is projected on the carrier coordinate system.The data is gradually corrected off-line through piecewise reverse correction and forward iterative solution.Combined with the actual needs of the project,the characteristics of pipe elbow and weld are identified and located.On the MATLAB platform,the algorithm of pipeline geographic coordinate positioning point correction and pipeline characteristic position recognition and positioning is programmed,and the pipeline geographic coordinate inertial mapping data calculation and correction are completed.Combined with the detector,the pipeline defect and characteristic position recognition and positioning are realized.The test and data solution results show that the inertial navigation system mounted on the detector in the pipeline can modify the pipeline inertial mapping trajectory in sections according to the positioning point information received by the detector,which can interrupt the error accumulation of the inertial navigation system during long-time operation,and can accurately identify and locate the characteristic position of the pipeline combined with the solution information.Using the measurement data of KVH1775 inertial measurement unit to solve,the trajectory linear correction algorithm can quickly correct the trajectory deviated from the positioning point;the position and attitude segmented iterative correction algorithm combines the positioning point and mileage wheel information to correct the attitude and speed of each sampling point of the inertial measurement unit,and recalculates after correcting the position,attitude and speed,so as to realize the pipeline inertial mapping trajectory segment by segment The results show that the two correction methods have good correction effect on the trajectory deviated from the positioning point in the experiment.By using the MPU6500 experimental data,the elbow characteristics can be accurately identified,and the elbow direction,angle,arc length and other information can be provided.In the actual engineering data,the pipeline weld feature recognition and location algorithm can effectively screen and identify the pipeline weld feature,and combine with the modified coordinates of the positioning point to carry out more accurate geographic coordinate positioning.