Real-time wheel–rail friction coefficient estimation and its application

The friction coefficient at the wheel–rail interface is crucial for the traction, braking and guidance of the railway vehicle. Real-time knowledge of the friction coefficient could reduce wheel–rail damages as well as improve the vehicle running performance. The friction coefficient is very difficult to be directly measured; hence an indirect measurement method using an unscented Kalman filter was proposed in this paper. A re-adhesion controller was also developed. The method was assessed in a Simpack-Simulink co-simulation environment. The friction coefficient estimation method was found to be accurate, and the re-adhesion controller improved the vehicle braking performance as well as reduced the wheel–rail damage.