Analyzing Automotive Networks using Virtual Prototypes
Sebastian Graf, Martin Streubühr, Jürgen Teich · 2011
Even small changes in automotive networks might have harmful impact to the correctness of the functionality due to changed timing behavior. In this paper, we present an approach to investigate the functional and timing-behavior of an automotive network at a very early design stage. To reach this goal, a virtual prototype of an automotive network is created. The prototype is used as a model for a simulation. The simulation allows a detailed analysis of the timing behavior of the system. As a case-study, a possible migration from a network architecture consisting solely of CAN and LIN to a FlexRay/CAN/LIN solution was investigated. We simulated different configurations and networking topologies and analyzed the results. It could be shown that it is advantageous to move components to the FlexRay bus, but certain issues concerning the configuration of the system, especially the networking topology, should be regarded carefully. The ever-growing complexity of electrical/electronic architectures (E/E architectures) becomes a major challenge for the design and analysis of future automotive systems. Key driver are advanced driver assistance systems like adaptive cruise control with high bandwidth demands, low response time and also the need for dependable timing. This forces significant changes in the network topology and, particularly, the communication infrastructure. One possible solution is the use of the FlexRay bus which offers high-speed communication with strict determinism. But the integration of new bus systems and the mixture of time-triggered and event-triggered components cause effects that may hardly be investigated manually. Changed timing behavior may affect the functional behavior and even lead to hazardous system states. Investigating timing properties, however, requires taking functional and architectural behavior into account concurrently. Given this situation, an efficient investigation requires the modeling and analysis of virtual prototypes assisting the designer during the development of the architecture. Our approach is based on simulations. For the use in an early design time, a virtual prototype of the automotive system is needed. The required results, which are used for the analysis of timing behavior, especially the latency of control loops, are gathered during the execution of the simulation. Therefore, this work will present how the functionality can be modeled in an actor-oriented functional network. Furthermore the various possibilities for modeling the architecture in a component network are described in detail. The virtual prototype combines the functional and the component network and therefore gives the opportunity to evaluate the timing behavior in conjunction with functional behavior. After the execution of the simulation, the results, especially concerning the timing, need to be analyzed in detail. For that, methods for the evaluation and analysis of the timing behavior are presented. The whole methodology will be shown with the help of a small case-study. The main goal of this study was to find an architecture that allows a control loop to lower its response time and to integrate a more dependable functionality then in the currently used configuration. The rest of the paper is outlined as follows: Section 2 discusses related work. While the problem targeted in this paper is outlined in Section 3, the used approaches are presented afterwards. The concepts of modeling and simulation of the functional and the architectural parts are introduced in Section 4. The analysis of the automotive networks is presented in Section 5. Section 6 presents a case-study from the automotive domain while Section 7 discusses the experimental results. The work is concluded in Section 8.