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Simulated Fault Injection for Time-Triggered Safety-Critical Embedded Systems

Iban Ayestaran

Director: Ao.Univ.Prof. Dipl.-Ing. Dr.techn. Peter Puschner Universidad: Technische Universität Wien



Safety-critical systems are dependable systems that could lead to loss of life, significant property damages or damages to the environment in case of failure, such as avionic and railway systems, offshore mills or nuclear power plants. Systems of this type must satisfy strict temporal constraints in order to guarantee certain safety properties. Besides, these systems must provide a certain degree of fault-tolerance, to guarantee that they keep a safe behavior even in the presence of faults in the system.
Historically, the control of safety-critical systems used to be handled by mechanical devices. However, due to the wide spectrum of possibilities that computer systems offer, these systems are nowadays commanded by computers. The most significant progress in this field may be the fly-by-wire system developed for the latest Airbus A380, which is fully controlled by a computer system. Moreover, the increasing functionality demanded by industry has lead to a considerable complexity growth. For example, high-end cars had about 70 electronic control units (ECUs) back in 2006 , and this number raised up to 100 by the year 2011.
Therefore, tackling the complexity challenge and preserving time properties and constraints throughout the development process are key challenges in the field. With this goal, this research work presents the Platform Specific Time-Triggered Model (PS-TTM), a novel model-based development framework based on SystemC for time-triggered safety-critical embedded systems. The proposed modeling work-flow tackles the complexity challenge following the MDA process and the Y-chart paradigm, by raising the level of abstraction at the very first development stages and creating a purely functional Platform Independent Model (PIM). Once this abstract model is validated, HW-related concepts are integrated into the model and the Platform Specific Model is generated.
The work includes the PS-TTM Automatic Test Executor (PS-TTM ATE), a time-triggered testing and simulated fault injection framework for the validation of both platform independent and platform specific models of systems. The PS-TTM ATE provides a simulation environment that enables the test developers to check the behavior of the system under the considered circumstances. Besides, PS-TTM ATE includes a non-intrusive fault injection mechanism that allows testing teams to inject faults in the models during simulation, in order to evaluate the effectiveness of the fault-tolerance mechanisms implemented in them before assembling a system prototype.

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