, Volume 26, Issue 2, pp 319-366
Date: 21 Oct 2012

Continuous KAOS, ASM, and formal control system design across the continuous/discrete modeling interface: a simple train stopping application

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A very simple model for train stopping is used as a vehicle for investigating how the development of a control system, initially designed in the continuous domain and subsequently discretized, can be captured within a formal development process compatible with standard model based refinement methodologies. Starting with a formalized requirements analysis using KAOS, an abstract model of the continuous system is created in the ASM formalism. This requires extensions of the KAOS and ASM formalisms, capable of dealing with quantities evolving continuously over real time, which are developed. After considering how the continuous system, described as a continuous control system in the state space framework, can be discretized, a discrete control system is created in the state space framework. This is re-expressed in the ASM formalism. The rigorous results on the relationship between continuous and discrete control system models that are needed to establish provable properties of the discretization, then become the ingredients of a retrenchment between continuous and discrete ASM models, and are thus fully integrated into the formal development. The discrete ASM model can then be further refined towards implementation.

Communicated by Eerke Boiten, John Derrick and Steve Reeves
The majority of the work reported in this paper was done while Richard Banach was a visiting researcher at the Software Engineering Institute at East China Normal University. The support of ECNU is gratefully acknowledged.
Huibiao Zhu is supported by National Basic Research Program of China (No. 2011CB302904), National High Technology Research and Development Program of China (No. 2011AA010101 and No. 2012AA011205), National Natural Science Foundation of China (No. 61061130541 and No. 61021004).