Wheel Sliding Protection system for safety in rail transport

The concept that plant safety must go hand in hand with engine excellence is increasingly entrenched. The Wheel sliding protection, the subject of the paper, is the device thanks to which the wheels are prevented from slipping and locking. Initially there is a digression about the braking system of the train and a comparison with its direct antagonist present in the automotive field: the ABS. Then there is the description of all its parts and the way in which they communicate with each other. All followed by the working principle of operation based on a detection and comparison of pulses provided by a speed sensor. We then refer to the WSP of the present day belonging to a third-generation that is daughter of the two previous ones that have however contributed to today's model and that are found into two independent devices: the low side WSP and the blocked axis detector. As far as the control system is concerned, the model proposed by Trenitalia is described and what today seems to be one of the most valid to be implemented: the Adaptive Fuzzy Sliding-Mode Control. The Trenitalia model is modeled as a first-order linear control system with linear equations. For this reason, already a priori this method of control is impossible to represent the optimal choice since many variables are not considered. In the case of Fuzzy control, for the ideal calculation of the input of the control system there is a much more complex procedure that winds between differential equations and approximations to Gaussian functions (to be able to obtain a limited approximation error) that will be omitted in this paper. After the description of the algorithm of both proposed models, graphs will be presented about the results of the simulations carried out to demonstrate what has been said about the superiority in terms of efficiency and correctness of the Fuzzy. After this part, we will refer to the problems and solutions to avoid incorrect operation of the WSP paying more attention to the speed sensor and related elements. Some devices that are independent of the device but that have the same purpose will also be presented: the low side WSP and the locked axis detector. In the final part, simulations are presented to test the correct functioning of the device and to demonstrate how its implementation on the wheels of vehicles always leads to an advantage. Ultimately, ideas for future development are presented.