Stefan Rothbauer

Component fault tree analysis resolves complexity: dependability confirmation for a railway brake system

In 2006 Siemens Transportation systems had to obtain an operating license for the brake system of a newly developed train. Therefore a safety analysis for the brake system had to be performed to show that the probability of a failure of the brakes is sufficiently small, less than specified limits. The safety analysis was performed by Siemens Corporate Technology. The probability of a failure of the brake system was calculated using hierarchical fault tree analysis. The large number of different combinations of subsystems contributing to failure scenarios was managed by a specially developed program for automatic generation of combinatorial fault trees. The most important result was the proof of the quantitative safety targets of the brake system to the regulating body.

Testing Safety Properties of Cyber-Physical Systems with Non-Intrusive Fault Injection – An Industrial Case Study

Non-intrusive, deterministic fault-injection tests provide evidence for making reliable statements about the behavior of safety-critical, real-time systems in the presence of software faults and component failures. These tests are derived from system safety requirements for the detection and handling of value and time errors. That the approach presented here works for distributed, time-triggered systems that process data cyclically and reserve resources exclusively for testing purposes has been demonstrated by an industry study confirming the feasibility of the concepts for a fail-operational electric car.