Research On High-frequency Wheel-rail Force Measurement Method Based On All-phase Filter

The measurement of wheel–rail force is the basis for studying vehicle dynamics.As the most commonly used wheel–rail force measurement technology,the instrumented wheelset uses the wheelset as a sensor to measure the wheel–rail force by measuring the strain at a limited point on the wheelset plate and converting it into an electric bridge output.The conventional dynamic test is processed by a low–pass filter when using the instrumented wheelset to measure,and can only analyze the low–frequency wheel–rail force.With the complexity of the train operating environment,under the influence of local wheel damage,wheel polygonal wear,rail joints,rail corrugation and external impact,the wheel–rail force often has obvious high–frequency characteristics.Expanding the measurement frequency of wheel–rail force and accurately measuring the wheel–rail force is of great significance to the safety and stability of train operation.The higher wheel–rail force frequency may cause the wheelset to produce modal resonance,so that the strain signal is amplified at the resonance frequency,and the strain frequency response curve peaks at high frequency,which has obvious interference to the accurate measurement of the wheel–rail force.Aiming at the shortcoming that the instrumented wheelset was only suitable for low–frequency wheel–rail force measurement,the wheelset was taken as the research object,and an all–phase filter was designed to correct the interference caused by modal resonance,so that the plate strain was related to the wheel–rail force.The rail force maintained a linear relationship,the measurement range of the force measuring wheelset was expanded,and the force measuring wheelset method can measure the high frequency wheel–rail force.The specific research contents were as follows:Based on the continuous measurement principle of the instrumented wheelset,the order of harmonic output by bridges under different methods was analyzed.And a wheelset finite element model was established to analyze the strain distribution law of the plate under static load.The harmonic orders and components of the vertical measuring bridge and the horizontal measuring bridge output under the national standard bridge method with different radii were studied to find the optimal cloth radius.Through harmonic response analysis,the strain response output of the web at different angles in the frequency range of 0 to 1000 Hz was analyzed,and the frequency response curve of the force measuring wheelset was obtained.Combined with wheelset modal analysis,the influence of wheelset modal resonance on strain frequency response curve was studied.The effect of resonance on the main frequency and main harmonic components of the group bridge signal was further analyzed.Combined with the natural frequency of the wheelset and the amplitude–frequency characteristics of the strain signal of the group bridge,a filter method was proposed to eliminate the influence of the peak generated by the resonance on the output of the group bridge.An all–phase filter was designed to filter the group bridge signal.The influence of parameters such as the number of sampling points and window function on the performance of the filter was studied,and the parameters to achieve the optimal performance of the filter were found.The wheelset was simulated and loaded in the time domain,and the time–domain variation and frequency characteristics of the wheelset strain under the action of different proportions of vertical force and lateral force were obtained.The calculated wheel–rail force value before and after filtering was compared with the actual wheel–rail force value,and it was verified that the filtered strain signal can accurately calculate the wheel–rail force value and reduce the resonance error.