Research On High-precise Inertial Surveying And Parameter Estimating Based On Smoothing And Filtering

With the rapid development of inertial technology,Inertial Navigation Systems(INS)have become feasible and popular approaches in inertial surveying applications.This paper studied several typical problems in high-precise inertial surveying applications based on the application background of railway track surveying.The main research and results are as follows:This paper researched on the fast and high-precise surveying method of geometric parameters of railway track without GNSS signal,and proposed a filtering and smoothing algorithm for track surveying based on IMU/odometer/landmark integration.By merging system errors with the same propagation characteristics,an observable system model was established,and the equivalent errors can be estimated and compensated together.This method solved the coupling problems between system errors under the condition of poor carrier mobility.By utilizing the optimal smoothing algorithm,we can get high-precise measurement of the track with few observation updates.Based on covariance analysis,the analytical relationship between railway track syrveying accyracy and equivalent gyro drifts was established.The simulation and experimental results show that the accuracy of the proposed algorithm for railway track surveying can reach 1mm(1?)when using medium precision gyroscopes while control points of the track control network position observations were provided by total station in about every 60 m interval.Compared with the traditional method,the precision of the new approach is equivalent,and the work efficiency can be improved remarkably.In order to overcome the requirement of high-precise control points,this paper proposed a railway track irregularity measurement approach using the INS combined with the Zero Velocity Updates(ZUPT)technique and sub-decimeter scale landmarks.The equations for calculating track irregularity parameters from absolute position errors were deduced.Based on covariance analysis,the analytical relationships among the track irregularity measurements with the drifts of inertial sensors,the initial attitude errors and the observations of velocity and position were established.Simulations and experimental results show that the relative accuracy for 30 m chord of the proposed approach for track irregularity surveying can reach approximately 1mm(1?)with medium precision INS while velocity observations are provided by ZUPT technique at about every 60 m intervals.This accuracy can meet the most stringent requirements of millimeter scale medium wavelength track irregularity surveying for railway lines.Furthermore,this approach reduces the requirement of high-precise landmarks which can lighten the maintenance burden of control points and improve the work efficiency of railway track irregularity measurements.A fast track surveying approach based on the Extended Kalman Filtering(EKF)and smoothing algorithm was researched,which solved the measurement of railway track under large initial azimuth error.The experimental results show that the proposed extended Kalman filtering and smoothing algorithm can achieve a high-precise accuracy of track irregularith paramenters without initial fine alignment,and the measurement accuracy is approximate to 1mm(1?),which effectively improves the quickness and flexibility of railway track surveying.The calibraction method for the error parameters of INS/odometer integration was proposed based on ZUPT technique.Considering that the positioning accuracy of ZUPT-aided INS is precise,taking use of the position provided by ZUPT-aided INS method to replace the landmarks for the calibraction of odometer error parameters.The simulation and experimental results show that the calibration method can effectively estimate the scale factor of odometer and the installation error between INS and odometer.The results are in good agreement with the method of using high-precise landmarks.