A thorough study of the OSEK/VDX standard. The history of the standard, its motivations and benefits, general architecture, as well as potential improvements for real-time embedded applications are discussed in this report.
In the past, the development of automotive systems has been primarily concerned with the design and integration of mechanical and electrical assemblies. In recent times, however, automotive manufacturers have faced increasing demands to deliver large amounts of complex embedded software. This software must now support the electronic control units that are increasingly replacing the traditional electromechanical systems and point-to-point wiring harnesses. This trend has become a crucial competitive factor for manufacturers since safety critical systems have stringent quality requirements and the cost of car recall programs is enormous. As a result, many manufacturers are developing their own software design environment, in order to keep full control over this crucial investment. This software design model creates two costly supplier-dependencies in the production chain. First, the ECU supplier has invested a large amount of money in an embedded software that is tightly integrated with the CPU architecture.
This makes it very difficult to switch CPU suppliers or reuse the software in newer versions of the product. Second, the car manufacturer will also have invested a lot in application software that is integrated into a proprietary layer from the ECU supplier, making the move to another supplier extremely expensive. The demand for more powerful and extensive features from the electronics systems in the car further contributes to the increasing complexity of embedded automotive software. In response to this emerging need, both the individual ECUs and the links between them are becoming increasingly complex. For example, the driver display system needs to receive messages from any malfunctioning component within the electronics systems.
All these challenges prompted the creation of the OSEK/VDX standard in the German and French automotive markets. This standard provides an open-ended architecture for distributed control units in vehicles and is subdivided into three layers. These are the Communication (COM), Operating System (OS), and Network Management (NM) layers. The COM layer is responsible for data exchange within and between control units; the OS layer allows the real-time execution of ECU software and acts as a base for the other modules; and the NM layer handles network configuration and monitoring. With the establishment of this standard, the automotive industry has enjoyed many benefits, including easier software portability, improved reliability, scalability and a significant lowering in redevelopment costs. The standard also offers enough functional advantages for use in other reliable real-time applications including manufacturing, household appliances, and intelligent transportation systems. This report will discuss the history of the standard, its motivations and benefits, general architecture, as well as potential improvements for real-time embedded applications.
Introduction
The OSEK/VDX standard refers to a combination of standards that were originally developed by two separate consortia and then later merged. The first group, OSEK, was founded in 1993 as a collaborative development effort of a group of German automotive companies, namely BMW, Bosch, Daimler Benz (now Daimler Chrysler), Opel, Siemens, Volkswagen, and the University of Karlsruhe, Germany. The name OSEK was derived from the German phrase “Offene Systeme und deren Schnittstellen fur die Elektronik im Kraftfahrzeug”, which effectively translates to “Open Systems and the Corresponding Interfaces for Automotive Electronics” [1]. OSEK's original objective was to address the high recurring costs in the development and redesign of Electronic Control Unit (ECU) software, as well as to improve the poor compatibility between these applications [2].
The VDX group, which draws its name from the acronym Vehicle Distributed eXecutive, was a similar initiative in the French automotive industry, led by the French companies PSA and Renault. VDX eventually merged with OSEK in 1994 and the two standards bodies declared their harmonized OSEK/VDX standard in October of 1995. Since then, numerous companies have joined the OSEK/VDX effort from different sectors of embedded systems development, including key players Hewlett-Packard, Motorola, NEC, and Texas Instruments [2].
Since the automotive industry created OSEK/VDX for its own market, the standard continues to be predominantly employed in automotive embedded applications. Such applications especially include controls in the vehicle's body function, air-bag deployment, chassis integration, and power-train systems. Today, the OSEK/VDX standard has significantly penetrated the technological sector of the automotive industry, so much so that many automotive manufacturers demand an OSEK Operating System (OS) as a mandatory component for controller software that is received from suppliers. Moreover, a set of OSEK certification requirements have been developed by the standards body, which must be met by any vendor who uses the OSEK/VDX trademark. This certification process ensures that different implementations of the standard conform to the specifications and that they are portable and interoperable with other OSEK/VDX tools. However, although the OSEK/VDX standard was originally targeted as a standard open architecture for automotive Electronic Control Units (ECU) in vehicles, the generic applicability of the resulting standard does not limit its usage to the automotive environment. More and more, this standard is being implemented in many stand-alone and networked devices, including those in the manufacturing environment, household appliances, intelligent transportation system devices, and more [3].
