Model-Based Testing of Embedded Systems Exemplified for the Automotive Domain

The purpose of this chapter is to introduce the test methods applied for embedded systems addressing selected problems in the automotive domain. Model-based test approaches are reviewed and categorized. Weak points are identified and a novel test method is proposed. It is called model-in-the-loop for embedded system test (MiLEST) and is realized in MATLAB®/Simulink®/Stateflow® environment. Its main contribution refers to functional black-box testing based on the system and test models. It is contrasted with the test methods currently applied in the industry that form dedicated solutions, usually specialized in a concrete testing context. The developed signal-feature-oriented paradigm developed herewith allows the abstract description of signals and their properties. It addresses the problem of missing reference signal flows and allows for a systematic and automatic test data selection. Processing of both discrete and continuous signals is possible, so that the hybrid behavior of embedded systems can be handled.

Architecture Description Languages for the Automotive Domain

The embedded electronic architecture of a modern vehicle is a distributed system composed of several tenths of nodes. The development of these systems relies on a cooperative process involving several partners (carmakers and several suppliers). In such highly competitive domain, three main factors have to be taken into account: the design and production costs, the performance, comfort, and quality of driving, and several stringent safety requirements. In order to fulfill these requirements in such a context, it is vital for the different stakeholders to master the effects of the different sources of complexity. One way to reach this goal is to provide them with a common modeling language capable of representing the system at all its design steps and a common reference architecture in terms of components and organization. This chapter illustrates this approach. It focuses on EAST-ADL, an architecture description language dedicated to the automotive domain. Its links to the reference architecture defined by the AUTOSAR consortium are given. The chapter focuses especially on the ability offered by EAST-ADL to support the validation and verification (V&V) activities in order to fulfill the safety requirements.

Abstract and Concrete Data Type Optimizations at the UML and C/C++ Level for Dynamic Embedded Software

An embedded system is a special-purpose system that performs predefined tasks, usually with very specific requirements. Since the system is dedicated to a specific task, design engineers can optimize it by exploiting very specialized knowledge, deriving an optimally customized system. Low energy consumption and high performance are both valid optimization targets to increase the value and mobility of the final system. Traditionally, conceptual embedded software models are built irrespectively of the underlying hardware platform, whereas embedded-system specialists typically start their optimization crusade from the executable code. This practice results in suboptimal implementations on the embedded platform because at the source-code level not all the inefficiencies introduced at the modelling level can be removed. In this book chapter, we describe both novel UML transformations at the modelling level and C/C++ transformations at the software implementation level. The transformations at both design abstraction levels target the data types of dynamic embedded software applications and provide optimizations guided by the relevant cost factors. Using a real life case study, we show how our transformations result in significant improvement in memory footprint, performance and energy consumption with respect to the initial implementation. Moreover, thanks to our holistic approach, we are able to identify new and non-trivial solutions that could hardly be found with the traditional design methods.

UML as Front-End Language for Embedded Systems Design

This chapter covers the use of UML as a modeling language for embedded systems design. It introduces the UML language, presenting the history of its definition, its main diagrams and characteristics. Using a case study, we show that using the standard UML with its limitations one is not able to model many important characteristics of embedded systems. For that reason, UML provides extension mechanisms that enable one to extend the language for a given domain, through the definition of profiles covering domain-specific applications. Several profiles have been proposed for the embedded systems domain, and some of those that have been standardized by OMG are presented here. A case study is also used to present MARTE, a new profile specifically proposed for the embedded system domain, enabling designers to model aspects like performance and schedulability. This chapter also presents a discussion about the effort to generate code from UML diagrams and analyses the open issues to the successful use of UML in the whole embedded system design flow.

SystemC Platform Modeling for Behavioral Simulation and Performance Estimation of Embedded Systems

Currently, embedded systems make use of large, multiprocessing systems on chip integrating complex application software running on the different processors in close interaction with the application-specific hardware. These systems demand new modeling, simulation, and performance estimation tools and methodologies for system architecture evaluation and design exploration. Recently approved as IEEE 1666 standard, SystemC has proven to be a powerful language for system modeling and simulation. In this chapter, SCoPE, a SystemC framework for platform modeling, SW source-code behavioral simulation and performance estimation of embedded systems is presented. Using SCoPE, the application SW running on the different processors of the platform can be simulated efficiently in close interaction with the rest of the platform components. In this way, fast and sufficiently accurate performance metrics are obtained for design-space exploration.

Separation of Concerns in Model-Based Development of Distributed Real-Time Systems

Software is increasingly being used to enable new features in systems in multiple domains. These domains include automotive, avionics, telecomunication, and industrial automation. Because the user of these systems is not aware of the presence of the software, this type of software is known as embedded software. More importantly, such a software, and the whole system in general, must satisfy not only logical functional requirements but also parafunctional (a.k.a. nonfunctional) properties such as timeliness, security, and reliability. Traditional development languages and tools provide powerful abstractions such as functions, classes, and objects to build a functional structure that reduces complexity and enables software reuse. However, the software elements responsible for the parafunctional behaviors are frequently scattered across the functional structure. This scattering prevents the easy identification of these elements and their independent manipulation/reuse to achieve a specific parafunctional behavior. As a result, the complexity of parafunctional behaviors cannot be reduced and even worse, the construction of those behaviors can corrupt the functional structure of the software. In this chapter, we propose a model-based framework for designing embedded real-time systems to enable a decomposition structure that reduces the complexity of both functional and parafunctional aspects of the software. This decomposition enables the separation of the functional and parafunctional aspects of the system into semantic dimensions (e.g., event-flow, timing, deployment, fault-tolerant) that can be represented, manipulated, and modified independent of one another from an end-user point of view. The realizations of these dimensions, however, do interact on the target platform since they consume common resources and impose constraints. These interactions can be captured during model construction and resource demands mediated during platform deployment. The use of semantic dimensions results in three significant benefits. First of all, it preserves the independence of the functional structure from parafunctional behaviors. Secondly, it enables the user to manipulate different parafunctional concerns (e.g., timeliness, reliability) independent of one another. Lastly, it enables the reuse of compositions along any dimension from other systems. The second core abstraction in our modeling approach is an entity called a coupler. A coupler expresses a particular relationship between two or more components, and can also be used recursively. Couplers enable the hierarchical decomposition of functional as well as parafunctional aspects. Aided by semantic dimensions and multiple coupler types, our framework enables the auto-generation of glue code to produce a fully deployable system. Our framework can also construct a detailed timing and resource model. This model in turn is used to optimize the usage of a given hardware configuration, or synthesize a configuration to suit a given software model. Our framework is implemented in a tool (de Niz, Bhatia & Rajkumar 2006) called SysWeaver that had been used to generate glue code and analyze the timing behavior of avionics, automotive, and software-radio pilot systems.

Concern Separation for Adaptive QoS Modeling in Distrbuted Real-Time Embedded Systems

The development of distributed real-time and embedded (DRE) systems is often challenging due to conflicting quality-of-service (QoS) constraints that must be explored as trade-offs among a series of alternative design decisions. The ability to model a set of possible design alternatives—and to analyze and simulate the execution of the representative model—helps derive the correct set of QoS parameters needed to satisfy DRE system requirements. QoS adaptation is accomplished via rules that specify how to modify application or middleware behavior in response to changes in resource availability. This chapter presents a model-driven approach for generating QoS adaptation rules in DRE systems. This approach creates high-level graphical models representing QoS adaptation policies. The models are constructed using a domain-specific modeling language—the adaptive quality modeling language (AQML)—which assists in separating common concerns of a DRE system via different modeling views. The chapter motivates the need for model transformations to address crosscutting and scalability concerns within models. In addition, a case study is presented based on bandwidth adaptation in video streaming of unmanned aerial vehicles.

Model-Driven Design and ASM-Based Validation of Embedded Systems

In the embedded system and System-on-Chip (SoC) design area, the increasing technological complexity coupled with requests for more performance and shorter time to market have caused a high interest for new methods, languages and tools capable of operating at higher levels of abstraction than the conventional system level. This chapter presents a model-driven and tool-assisted development process of SoCs, which is based on high-level UML design of system components, guarantees SystemC code generation from graphical models, and allows validation of system behaviors on formal models automatically derived from UML models. An environment for system design and analysis is also presented, which is based on a UML profile for SystemC and the Abstract State Machine formal method.

Using Timed Automata for Modeling the Clocks of Distributed Embedded Systems

Model checking is a widely used technique for the formal verification of computer systems. However, the suitability of model checking strongly depends on the capacity of the system designer to specify a model that captures the real behaviour of the system under verification. For the case of real-time systems, this means being able to realistically specify not only the functional aspects, but also the temporal behaviour of the system. This chapter is dedicated to modeling clocks in distributed embedded systems using the timed automata formalism. The different types of computer clocks that may be used in a distributed embedded system and their effects on the temporal behaviour of the system are introduced, together with a systematic presentation of how the behaviour of each kind of clock can be modeled. The modeling is particularized for the UPPAAL model checker, although it can be easily adapted to other model checkers based on the theory of timed automata.

High-Level Design Space Exploration of Embedded Systems Using the Model-Driven Engineering and Aspect-Oriented Design Approaches

Modern embedded systems have increased their functionality by using a large amount and diversity of hardware and software components. Realizing the expected system functionality is a complex task. Such complexity must be managed in order to decrease time-to-market and increase system quality. This chapter presents a method for high-level design space exploration (DSE) of embedded systems that uses model-driven engineering (MDE) and aspect-oriented design (AOD) approaches. The modelling style and the abstraction level open new design automation and optimization opportunities, thus improving the overall results. Furthermore, the proposed method achieves better reusability, complexity management, and design automation by exploiting both MDE and AOD approaches. Preliminary results regarding the use of the proposed method are presented.