Abstract:

This paper applies reference governor (RG) design to the problem of preventing excessive wheel-slip in railway vehicles with pneumatic brakes. The RG minimizes the difference between the desired and implemented deceleration set-point such that the system state remains inside a constraint admissible positive invariant set where wheel-slip is maintained below a prescribed level. This problem is complicated by the non-linear slip-dynamics and hysteresis in the pneumatic brake which results in a non-convex invariant set. The RG is evaluated in numerical simulations where we observe that the governor produces non-linear integral-action that has the beneficial properties of fast transient response and offset-free tracking while being robust to delays from hysteresis and uncertainty on the slip dynamics.