Active and semi-active control of uncertain railway wheelset

By increasing the operational speed of railway vehicles, dynamics and wear phenomena play a very important rule in the design phase of vehicle components; especially, attention should be paid to the most important part-the wheelsets. The other problems designers usually face include the field of parametric uncertainties of the wheelsets, such as geometrical and physical parameter uncertainties. It is obvious that certain barriers have to be taken in order to avoid unrequired dynamics and wear. Besides the aforementioned reasons, economy also plays a very important role in everyday operation, due to wheel damage. Recent studies show the effect of using active and semi-active control strategies on railway wheelsets. From an active control strategy, the applicability of robust H_∞ control (RLQR) is examined, where the problem is solved as a direct state feedback problem, assuming that all state variables are available directly. From semi-active control strategies, the DSAD, DESAD and CSAD methods are presented and the so-called relative velocity compensation method is also considered. For practical purposes, the simple sky-hook compensation technique is also investigated, which is very challenging in railway vehicle applications. The nonlinear dynamic behaviour of controlled active and semi-active railway wheelsets is investigated by means of a numerical integration method