A fault-tolerant architecture for computer-based railway vehicle brake systems

Abstract

Abstract

In this paper a computer architecture is presented which is suitable for distributed control systems where fault tolerance is desired. The architecture is designed for implementation mainly with standard components ‘off the shelf’ (COTS). In particular there is only a comparable small device called fault-tolerant communication control (FTCC) that requires extensive redundancy. The FTCC is used to close control loops as tightly to the controlled physical device as possible, gaining from the excess computing capacity that a distributed system offers but at the same time removing the impact of increased fault intensity from an increased number of processing elements.

The architecture is preferable for applications where there is some kind of natural inherent redundancy. As a starting point, and also as a case, a state-of-the-art brake control system for railway vehicles is considered. Common computer architectures designed to handle safety-critical applications are recaptured and a feasible solution arrived at in the shape of a slightly modified distributed architecture. This revised distributed architecture is then applied and a revised brake control system is described.

The FTCC device has been implemented, but without redundancy, with standard VHDL (very high speed integrated circuit hardware description language) tools and tested in a simulator environment. Results are promising and indicate that the FTCC device has a great potential in future ‘control-by-wire’ designs.