Dynamic adhesion model and adaptive sliding mode brake control system for the railway rolling stocks

Abstract

Main factor of the braking mechanism for the railway rolling stocks is the adhesion force which is a friction force occurred between rail and wheel. Mathematically, the adhesion force is a function of the slip ratio which is a relative velocity between the rail and wheel, and its magnitude depends on the condition of the rail surface and axle load. Although, the adhesion force affects considerably the performance of the traction and the braking of the rolling stocks, it is impossible to measure it in the real time. Huge amount of attention is given to the modelling of adhesion force. However, the previous proposed models show only the static relation between slip ratio and adhesion force that is induced by experimental experiences. In the current paper, novel dynamic model of the adhesion force is proposed under the assumption that the wheel slip is regarded as the irregular contact between the wheel and rail surface. Based on this proposed adhesion force model, the brake control system is designed using adaptive sliding mode control scheme to realize robust antislip brake control. In the controller design process, the running resistance and unmodelled system dynamics are considered as system uncertainty, and the weight of rolling stocks is represented as changeable parameter and adaptive law is induced using Lyapunov stability theorem. The performance of the proposed antislip brake control system using novel adhesion force model is evaluated by the computer simulation.