Research On Robust Estimation Method And Algorithm Of Vertical Alignment Reconstruction

Vertical alignment reconstruction plays an important role in railway maintenance.During the long-term operation of the existing railway,under the combined action of static force,dynamic force and natural environment,the geometric shape and position of the track are constantly changing,resulting in the geometric irregularity of the railway track,which reduces the operational safety and comfort.With the increase of train speed,the geometric irregularity of the line has an increasingly significant impact on driving safety and comfort.Only regular inspection and maintenance of the line can meet the requirements of safety and smoothness.To realize a robust model for the vertical alignment reconstruction of the existing railway,this paper compared the performance of various algorithms from the unit alignment to the overall alignment.The main contents are as follows:(1)The simplest parameter set and robust estimation model are proposed.Based on the 1-norm criterion and the simplest parameter set,a robust estimation model satisfying the internal continuity constraint is established.(2)Parameter estimation of the unit alignment.According to the parameter model,the straight line and vertical curve error equations are established.Classical cases are selected,and the steepest descent method,conjugate gradient method and Levenberg-Marquardt(LM)algorithm are used for comparative analysis,which lays the foundation for the selection of the overall alignment reconstruction algorithm.Through two cases with gross errors,the robustness of the 1-norm model is verified by comparing the fitting results under the 1-norm and 2-norm criteria.(3)Lagrange multiplier method and penalty function method are used to model the constraint conditions,and the robust estimation model under the constraints is realized.By comparing the parameter estimation of a vertical alignment with constraints between the two methods,it is concluded that the penalty function method is more effective than the Lagrange multiplier method.(4)Robust parameter estimation on the overall alignment with constraints.Combined with the requirements of line slope,vertical curve length,and limitation of lifting and falling amount,the penalty function method is used to model the constraints,and the robustness and efficiency of the robust estimation model under the constraints are verified by an actual engineering case.The research contents of this paper have been realized and verified in MATLAB program simulation software.The thesis includes 15 pictures,14 tables and 65 references.