Continuous measurement of derailment quotient and wheel-rail contact position in railway vehicle using axially-asymmetric bridge circuits and orthogonal weighting functions

Instrumented wheelsets are widely used in the railway industry for the purpose of measurement of the wheel-rail interaction forces, which are crucial factors in a running safety assessment. Recently, the author proposed a new configuration of bridge circuit for measuring wheel-rail lateral force, which are categorized as “axially-asymmetric bridge circuit.” The merit of this type of bridge circuit is to reduce the measurement error associated to the lateral contact point shift. In this study, we propose a highly accurate continuous measurement method of the derailment coefficient based on “orthogonal weighting functions” that utilizes the characteristics of an axially-asymmetric bridge circuits. A continuous measurement method for the lateral contact position is also proposed utilizing the concept of the orthogonal weighting functions. The validity of the proposed method was confirmed through roller-rig tests.