Robust adaptive re-adhesion control for high speed trains

Effective re-adhesion control is plays an important role in enhancing safe and reliable operation of high speed trains (HST). This paper presents a robust adaptive re-adhesion control strategy for HST. This control algorithm developed is not only able to attenuate wheel skid timely, but also capable of utilizing available adhesion properties to maintain preferable traction/braking performance after re-adhesion, even if the rail-wheel system exhibits significant adhesion uncertainties and nonlinearities. To achieve satisfactory slip velocity tracking, an optimal seeking strategy is introduced to provide the desired slip velocity. It is shown that the proposed strategy can automatically adjust the control torque to drive the train in the way to make it operate away from slip region but closer to the neighborhood of the optimal adhesion point, such that preferable traction/braking capability is guaranteed after re-gaining adhesion. Effectiveness of the proposed re-adhesion strategy has been confirmed by theoretical analysis and numerical simulation.