A Multi-layered Statechart Diagram Including Mitigation Behavior

Safety critical system such as Unmanned Aerial Vehicle, Medical system, Railroad control system and so on includes software in it. It is called Embedded software. Model based testing is a recommended solution for testing embedded software. It needs a specific model that it designs test cases from, and its testing quality totally depends on the model's quality. Unlike the traditional software, the embedded software is expected to control risky situation. It means that the mitigation of risk is necessary. Therefore a model should include mitigation information for testing mitigation behaviors of embedded software. This paper proposes a diagram including both of normal behaviors and their mitigation behaviors. The mitigation behavior supports failsafe behavior, and Model based testing using the multi-layered statechart diagram results in failtsafe testing, which checks if the system mitigates risk well and doesn't go to failures at all.