Test bench concept cuts changeover time: Page 5 of 6

September 27, 2017 //By Norbert Witteczek, Smart Testsolutions
Test bench concept cuts changeover time
The strong increase in the number of electronic control units in vehicles is accompanied by an increase in testing effort. In order to keep the time for the test procedures to a minimum, the measurement technology specialist Smart Test Solutions and the automotive supplier ZF Friedrichshafen AG (ZF) have developed a new generation of test benches; the development focus was on maximum flexibility in use. The system described is used for ZFs captive supply.

This enables them to react swiftly if the requirements suddenly change. There is no need for any complex tools or development environments. It is only necessary to write a comparatively simple script in a standard text editor and transfer it in file form to the test controller, which Smart Testsolutions also refer to as the process module.

Nearly all the ZF scripts were created in-house, but the company also benefits from the fact that, once programmed, modules can be re-used and test sequences can be defined independently of the operating software of the test benches. The flexibility of the test benches, of which ZF now has more than 30 in use around the world, has led to a drastic reduction in changeover times. The test benches were first employed for testing control units for an electronic traction control system. Siefert-Gäde's test equipment team only needed four weeks to convert them for testing a camera system. "In the past it would have taken us eight months," says the test bench expert.

ZF TRW has more than 30 test benches
and well over 200 subracks in use around the world.

The test bench already included most of the measuring equipment required, as the traction control system with integrated parking brake for which it was originally designed is one of the most complex modules in the portfolio of the ZF division in terms of the electronic interfaces. As the test systems have a special evaluation assembly (EVA board) for each unit under test, any necessary electrical adaptation to the I/O channels of the units under test can be performed in-house by ZF. According to Siefert-Gäde, use of the EVA board and Lua scripting permitted quick adaptation of the I/O interfaces to the camera system. He further explained that the main differences between testing camera systems and traction control systems are the complexity of communication and the difference in loads. For the camera system use is made of CAN and Automotive Ethernet, for which the company employs an additional Vector module (VN5610), whereas the ESP only involves CAN, FlexRay and LIN."

Outlook: Lightweight commands for Industry 4.0

The Lua scripting capability does not just shorten changeover times however. Thanks to the integrated Lua script interpreter the new test bench generation is also well equipped to deal with the Industry 4.0 scenarios of the future. Requiring only minimal resources, the Lua scripting language is ideal for use in small networked devices and control systems. This is why the first manufacturers are already starting to implement Lua as a basis for networked machine intelligence. The progress of industrial automation will also extend to test departments. One feasible scenario could be: The unit under test communicates with the test bench and identifies itself. The test bench then performs configuration automatically on the basis of this information.

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