Influence of signal-to-noise ratio on the accuracy of experimental determination of wheel-rail interaction forces

Abstract

This paper analyzes the influence of the signal-to-noise ratio (SNR) on the accuracy of the experimental determination of wheel-rail interaction parameters – vertical force Q, lateral force Y, and contact point position ytk. The research was conducted on an instrumented wheelset developed from a standard wheelset, with strain gauges optimally positioned and connected into Wheatstone bridges. Experimental tests were carried out on a specialized test stand within the Laboratory for Railway Engineering and Structural Testing at the Faculty of Mechanical and Civil Engineering in Kraljevo, University of Kragujevac. The noise level in the electronic components of the measurement system and its influence on the final measurement error were analyzed based on the results of corresponding static and dynamic measurements. Using appropriate statistical analysis, it was determined that the noise level originating from the Wheatstone bridges and associated electronics causes significant dispersion of output signals, especially at lower force intensities. The results show that under lower loads (characteristic of empty vehicles) the SNR is less favorable, leading to an increase in the relative measurement errors of the aforementioned parameters. Conversely, under higher loads and critical values of the Y/Q ratio, which are of interest for assessing vehicle running stability according to relevant international standards, the SNR is significantly more favorable and measurement errors decrease. The obtained results confirm that the SNR is a key factor in the reliability of the measurement system for the experimental determination of wheel-rail interaction parameters. One of the directions for further improvement in measurement accuracy is the application of modern fiber-optic sensors, which have significantly higher resistance to electromagnetic interference and enable a more favorable SNR, thus opening a promising path toward a new generation of instrumented wheelsets with even higher measurement accuracy.