Modeling and Validating Distributed Embedded Real-Time Systems with VDM++

Abstract

The development of complex embedded control systems can be improved significantly by applying formal techniques from control engineering and software engineering. It is shown how these approaches can be combined to improve the design and analysis of high-tech systems, both in theory and practice. The semantics of the integration of two established rigorous techniques has been defined formally in this work. The strength of this integrated semantics is demonstrated by means of a significant industrial case study: the embedded control of a printer paper path, whereby the full development life-cycle from model to realization is covered. The resulting model-driven design approach fits the current engineering practice in industry and is both flexible and effective.

Validation Support for Distributed Real-Time Embedded Systems in VDM++

“…The approach has a formal basis, but the goal is pragmatic. Building on an existing modeling framework in VDM++ [20], we have presented a new semantically wellfounded facility for stating and checking system-level validation conjectures against traces derived from the execution of models that describe distributed real-time systems. Tool extensions have been defined formally and have been implemented to proof-of-concept level.…”

“…Our example, based on an in-car radio navigation system, was introduced in the context of performance analysis [21,12] and also as a case study in the extension of VDM++ to model timing requirements and distributed architecture [20]. The navigation system consists of several software applications running on a common distributed hardware platform.…”

“…This section contains extracts from the VDM++ model of the in-car navigation example initially presented in [20]. We focus on the system model rather than the environment model.…”

“…The approach is based on the Vienna Development Method (VDM), an established formal method which has been extended to support modeling of concurrent objectoriented systems (VDM++ [5]) and real-time and distributed systems [20]. In this paper we define new extensions to the modeling language and tools to permit the expression of system-level timing properties and support their validation against timed traces derived from the execution of scenarios on VDM++ models.…”

Getting Software Engineering out of Isolation

“…Models of digital controllers -often software-based-usually do not reference time at all and instead treat the model of the controller in terms of discrete events that trigger specific reactions from the controller; these models are based on discrete mathematical domains [6]. In order to be able to appropriately balance concerns from control engineering with software engineering and taking potential faults into account a common model that can be analysed is needed [7]. The challenge can be further extended when different systems can provide added benefits for its users by interaction with other systems.…”