A new method to measure the distance between backs of the wheel flanges based on wavelet analysis denoising

The distance between backs of the wheel flanges is key parameter that influences the wheel-rail contact. This parameter will change with the change of the flange thickness of wheelsets. The measuring system based on the laser displacement sensors is proposed to measure this parameter on line. The measuring results are improved by the wavelet analysis. The RMSE of the manual measurement and the wavelet analysis are 0.33, and 0.22, respectively. The changing range of manual measurement is much larger than the measuring system because of the difference between every operator's measuring standard. That shows the measuring system has the better repeatability and reliability. These results show that the system based on the laser displacement sensors can meet with the measuring requirement on line.