Friction coefficient estimation using an unscented Kalman filter

Abstract

The friction coefficient between a railway wheel and rail surface is a crucial factor in maintaining high acceleration and braking performance of railway vehicles; therefore, monitoring this friction coefficient is important. Due to the difficulty in directly measuring the friction coefficient, the creep force or creepage, indirect methods using state observers are used more frequently. This paper presents an approach using an unscented kalman filter to estimate the creep force and creepage and the friction coefficient from traction motor behaviours. A scaled roller rig is designed and a series of experiments is carried out to evaluate the estimator performance.

Keywords:

• friction estimation
• Kalman filter
• traction motor