The following technical report is available from http://aib.informatik.rwth-aachen.de:
Entwurf eingebetteter Software mit abstrakten Zustandsmaschinen und Business Object Notation Daniel Klünder AIB 2009-04
The ever increasing presence of information technology along with the pervasion of hardware and software into everyday life boosts the need for engineering methods and tools for the development of high quality embedded systems. This trend is further amplified by the rising complexity of such systems and their usage for safety critical tasks. However, classical software engineering methods lack support for the peculiarities of embedded systems. This thesis therefore extends these methods with support for verification and requirements that arise through interaction with the physical world.
Abstract state machines (ASMs) are used for functional modeling and extended with an abstract notion for feedback control algorithms by utilizing non-deterministic choose. For their verification this thesis presents a novel approach to model checking ASMs that directly supports them by utilizing their notion of run. The simulator CoreASM is adapted to branch into all possible successor states and integrated into the model checker [mc]square. On the one hand, this enables the approach to present counterexamples and witnesses directly as sequences of ASM states, to be easily extendable, and at the same time supports the whole CoreASM syntax. On the other hand, it suffers from the simulator's design that was built with the goals of comprehensiveness and extendibility in mind and hence is not optimized for performance in a model checker.
The Business Object Notation (BON) is used for structural modeling and extended with the representation of concurrent classes. Requirements that arise through the execution of the embedded system on a physical platform are represented in preconditions while those that arise through reactions to the physical environment are modeled in postconditions. The former is only useful for short methods.
While ASMs can easily be transformed into an implementation, timed and concurrent BON models need an extra runtime environment for a semi-automatic translation. Therefore, simple concurrent object-oriented programming (SCOOP) is implemented on a real-time operating system and extended with the runtime checking of time assertions in postconditions. Because of the unpredictability of runtimes it is only practical for soft real-time systems and improves the system's reusability at the expense of its resource usage.
For evaluating the approach an adaptive cruise control which includes two closed loop controllers, interaction with the environment via sensors and actuators, time requirements, and safety critical functions is successfully implemented.