Today's cars are computers on wheels, each one containing up to 80 embedded computer systems and control units as well as around a gigabyte of software to control the car's components and technical extras, from brake assist systems and CD players to satellite navigation systems. Safety-critical software everywhere and Fraunhofer ISST has developed solutions to help getting a grip on it.
“The desire for greater comfort and safety is producing increasingly complex systems”, states Markus Hardt, an engineer at the ISST and official representative of the Fraunhofer-Gesellschaft at AUTOSAR. Their smooth interaction is becoming more and more difficult. The fact that these components often come from different suppliers with different technical standards doesn't help integration. This is where AUTOSAR (Automotive Open System Architecture), an initiative of various car-manufacturers and their suppliers founded in 2003, wants to make a difference. To enable seamless integration of the system and software components in cars, the AUTOSAR partners are developing the first ever uniform standard for automotive software.
Picture credits: Fraunhofer ISST
The German research foundation Fraunhofer-Gesellschaft is a premium member of AUTOSAR. Some of its institutes, namely the Fraunhofer Institute for Software and Systems Engineering ISST in Berlin, the Fraunhofer Institute for Open Communication Systems FOKUS in Berlin and the Fraunhofer Research Institution for Communication Systems ESK in Munich, are making their expertise available to the AUOTSAR partnership in a variety of areas, including system descriptions, diagnosis and automobile operating systems, and testing and quality assurance. They are also driving the interchangeability of software components between different vehicle platforms.
Every embedded system has to be individually adapted to suit each vehicle type – and for individual cars such customizing would normally involve a huge amount of time and effort. The fact, for instance, that a customer might not want air conditioning in his Golf GTI has to be taken into account by the developers from the word go, along with the potential effects of this decision on 80 other control units in the car. This is where the Fraunhofer ISST can help with its aXBench software, which can be used to individually combine the countless number of automobile functions for various car models and variants. The latest version of aXBench offers improved variant management, which provides developers with strategic support in designing the system architecture. As a result, the different choices made by customers can be implemented more easily.
aXBench helps engineers to compare different potential solutions, allowing them to estimate at a very early stage the expected size of the code and the time and effort needed for development and testing. “You don't get to grips with variance by retrofitting software with all the parameters you need to cover every possible configuration”, explains Markus Hardt. “On the contrary, variance has been systematically factored in right from the very start.”
Making the work of the developers of AUTOSAR software components easier is the objective of researchers at the ESK. On behalf of the BMW Group they have developed DLT (Diagnostic Log and Trace), a module with an integrated transfer protocol and storage format. This enables developers to display information on the status of their AUTOSAR software with the aid of log-and-trace data. “The DLT's uniform interfaces and its standardized transfer protocol and storage format for log-and-trace data makes system integration and software acceptance a breeze”, says Falk Langer, a scientist at the ESK.
To afford passengers the highest levels of safety and comfort, automobile control systems have to reliable. But will they function reliably in accident situations? That is ultimately a question for quality assurance, and one that can be answered with systematic testing procedures and standardized test environments. The internationally standardized testing language “TTCN-3 embedded” makes this happen: TTCN-3 embedded was designed mainly to support the car industry in testing safety-critical systems, enabling the safer, more efficient and cost-effective design of quality assurance processes for software components. Above and beyond this, the standard offers a systematic, multivendor approach to testing for automotive quality assurance.
The Assessment Studio program is another solution from the Fraunhofer FOKUS that supports developers in creating AUTOSAR-compliant applications for embedded systems. It allows developers and engineers to check their functional models for compliance with standards if they are to create safe, efficient software. In this context it is essential that the models are correct and consistent. Up till now, modelers have carried out this job manually, but as models grow ever more complex, the manual approach is becoming too error-prone and time-consuming. Assessment Studio handles this task automatically, checking the functional models and related documentation for compliance within a matter of seconds, regardless of the platform used. The program also provides the corresponding rules, such as AUTOSAR, as part of the package. As Tibor Farkas, Project Manager at the FOKUS, comments: “With our program, engineers can be certain that their applications conform with AUTOSAR.”