Train Speed Measurement Approach Based on Wheel-axle Creep Rate Detection

Abstract

Objective In urban rail transit systems, train velocity measuring and positioning technology offers critical information to many applications such as train autonomous driving, collision avoidance, dispatching and directing. The architecture and function of the train control systems are increasingly complex, and the continuous level-up of the operation efficiency and the services requires higher performance for train velocity measuring and positioning, so that the ability of the ATP (automatic train protection) measuring velocity and positioning in different scenarios needs to be improved. Method A train velocity measurement approach based on wheel-axle creep rate detection is proposed. First, the architecture of the train velocity measurement and localization system is introduced and the technical process of train velocity measurement based on wheel-axle creep rate is explained. Then the wheel-axle creep theory is explained and the velocity measurement error of the Doppler radar sensor is modeled to obtain the radar maximum reference velocity, which is used to calculate the wheel-axle creep. Different compensation for the odometer velocity is applied based on different wheel-axle creep status. Finally, the velocity measurement approach proposed is verified using the experimental data sets. Result & Conclusion The experimental results show that most of the time the wheel-axle is in a low creep state during the train braking stage. The velocity obtained by less compensation for the odometer velocity is much lower than the maximum velocity calculated by the existing ATP. This approach remarkably improves the velocity measurement accuracy under the premise of safety when the train minimal velocity is identical.

Keywords

• urban rail transit
• automatic train protection
• train velocity measurement
• odometer
• doppler radar
• wheel-axle creep detection