Airbags, anti-lock brakes (ABS), electronic stability control (ESC), adaptive cruise control (ACC) and a host of other drive aids are increasingly common as standard equipment, meaning more electronic features per car, and more people relying on those features. How do the suppliers of such systems make sure that their products perform? Robust design and manufacturing processes, testing and an increasing trend towards system integration. Simulation, as it almost universally accepted, is the most efficient way to test in the early phases of development. Not only can models evaluate almost all configurations, scenarios and failure modes, they help to eliminate unsuitable designs at the earliest possible stage. Simulation is constantly increasing because the tools are getting better, giving the oportunity to save time and run through all conceivable failure modes. It may take months to build a simulation model, but once it is available, one can generate sweeps of independent parameters and let the simulator work on running all those combinations overnight. The results are only as good as the model and although accrued skills, knowledge and experience are a sound basis to work from, validation is still required. Simulations do not always reduce the timescale of the test program but will certainly increase overall efficiency. Most suppliers believe that whole vehicle testing is particularly important for two key areas of testing: electromagnetic compatibility (EMC) and noise, vibration and harshness (NVH). Given the increasing electrical and electronic content of vehicles - especially so in the case of hybrids - there are increased risks form electromagnetic interference. Modelling will highlight most of the problem areas but untill complete complete prototypes are made available, the behaviour of the systems is not certain; EMC remains an area where here can be surprises. NVH can also cause problems, especially if the data files used in the simulations are obsolete once the first prototype is delivered. Environmental tests are a mixture of laboratory and real world conditions, but as simulation takes ever more responsibility, full vehicle testing is reduced. Test tracks are still an important part of the program and with carefully designed durability cycles can produce the effect of 150000 real world miles on just 30000 miles on the track. Highly accelerated life testing (HALT) chambers may be used to identify the limit of any electromechanical system, using extremes of temperature and vibration. For durability testing, the ECU undergoes several vibration tests. Yaw rate sensors, an essential component of ESC systems, need to be carefully mounted to avoid distortion of their output signals so mounting brackets and housings must have very carefully designed mass, stiffness and natural frequency. Electrical connectors are a risk item but better mounting and sealing methods have reduced their susceptibility to water ingress and failure under vibration. These can be rated up to IP67 level; resistant to water under pressure. For first generation, there are clearly risks involved, including fail safes and redundancies. Such architectures require particularly close cooperation with the OEMs. Thereafter, the experience and knowledge will make second generations and established product and therefore even more reliable. It is also likely that the cost reduction programmes of OEM will drive suppliers to integrate their systems even further.


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    Titel :

    Testing: Electronic complexities. A real test for electronics in combination


    Weitere Titelangaben:

    Testen: Elektronische Komplexität. Prüfung gegenseiter Abhängigkeit elektronischer Systeme


    Beteiligte:

    Erschienen in:

    Automotive Engineer ; Nov ; 30-32


    Erscheinungsdatum :

    2006


    Format / Umfang :

    3 Seiten, 5 Bilder



    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch





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