Estimation of the railway equivalent conicity under different contact adhesion levels and with no wheelset sensorization

The running stability of a railway vehicle, which is highly relevant for operational safety, strongly depends on the shapes of the profiles of wheel and rail, which change during the progress of wear. The model-based condition monitoring of a key parameter, such as the wheelsets equivalent conicity, is one of the approaches to realize condition-based maintenance and ensure railway vehicles reliability and running safety. A constrained nonlinear estimation technique is developed in this paper concerning the monitoring of the equivalent conicity. Suitable modelling of the railway vehicle dynamics is presented for the model-based estimator synthesis to perform the equivalent conicity monitoring employing only the carbody and bogie frame measurements, taking into account the track adhesion level variation. This approach allows avoiding the wheelset sensorization affected by a harsh and vibrational environment, thus reducing the possibility to produce inaccurate measurements. Another direct consequence of this approach is the reduction of costs relative to vehicle sensorization. Moreover, the possibility to constraint the estimated vehicle states and parameters allows considering their operative acceptance limits.