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Cartronic~The ordering concept for flexible configuration of electronic vehicle subsystems
Published September 03, 1998 by AVL List GmbH in Australia
The further development of vehicle electronic systems is characterized by demands for increasingly better safety, comfort and fuel consumption. Further development becomes necessary, for example, when legislation is made more stringent or functions that are familiar from information and entertainment electronics are integrated. All these demands have to be met under a constant pressure to keep costs down.
Car electronics have now reached a stage where they represent a factor in determining functions and values. Accompanying the growing number of electronic systems in the vehicle is the disproportionate rise in the cost of developing them. Not only that but a multitude of new functions are also emerging and, of course, the growing number of functions means increasing complexity of the electronic structures in the vehicle.
The necessary costs and development time as well as the difficulty of mastering the resultant complexity have to be balanced against the objective of implementing an improved, new scope of functions. A substantial help in resolving this conflict of objectives is to network the systems that have so far been largely autonomous, such as engine control and ABS, in a Car-Wide Web and to standardize the Web components and their interfaces. This naturally entails greater demands on the software structure and development. The software structure must therefore permit distributed development and testing of individual functions in the form of components. Components, here, is taken to mean subsystems of the electronic control system, rather than physical assemblies. The exchange of standardized information between the subsystems will make it easier to implement more and/or improved functions and to simplify the current individual systems.
An example of the utilization of such synergies for active safety in today's vehicles is the traction control system (ASC). It is only possible due to the ASC's communication with the engine management system to influence the drive torque. In the long term, systems from the areas of engine and transmission control, driving stability monitoring, comfort and communication will merge and thus decisively improve safety and comfort for vehicle users.
A networked system like this places greater demands on safety, reliability and the coordination of the subsystems. To be able to meet these criteria despite the increasing complexity, the system network must be structured systematically. The structure must define the cooperation of the subsystems and suitable interfaces between them.
The aim here is, on the one hand, to implement functionalities that extend beyond the sum of the individual system functions, and on the other to avoid mutually negative effects between the interlinked systems.
As the basis for such a network of electronic subsystems in the vehicle, BOSCH is developing an open system architecture called CARTRONIC. Here, subsystems are components with defined tasks, such as engine control or vehicle dynamics control, rather than actual control units. This open architecture can be used in all types of vehicle and control unit configurations, and allows the integration of systems from different manufacturers.
Following this introduction, section 2 explains the basic ideas of the CARTRONIC concept. Section 3 discusses the top layer of the architecture of the vehicles electronic systems. It describes the details of some of the subsystems and illustrates by way of concrete examples how they interact. Section 4 deals with the structure of the latest BOSCH engine control system for SI engines, the Motronic ME7, integrated in the Car-Wide Web. The paper finishes in section 5 with a summary and a look at future developments.