Detection of wheel-rail conditions for improved traction control

Novel detection techniques of wheel-rail contact condition, that exploit the dynamic properties of the conventional solid axle wheelset in response to changes at the wheel-rail interface, are studied in this paper. The main aim is to develop an ability to identify/predict adhesion limit to overcome the problem of wheel slip/slide in poor contact conditions where the adhesion is low. Two possible solutions are introduced. One of the proposed methods detects the wheel slip indirectly from the wheelset dynamic changes caused by the wheelsets operating in the unstable region of the non-linear contact characteristics as a consequence of wheel slip. The second method estimates the contact force saturation and identifies the maximum adhesion using a model based technique that involves the use of multiple Kalman filters.