Development of Universal Brake Test Data Exchange Format and Evaluation Standard 2010-01-1698
Brake system development and testing is spread over vehicle manufacturers, system and component suppliers. Test equipment from different sources, even resulting from different technology generations, different data analysis and report tools - comprising different and sometimes undocumented algorithms - lead to a difficult exchange and analysis of test results and, at the same time, contributes to unwanted test variability. Other studies regarding the test variability brought up that only a unified and unambiguous data format will allow a meaningful and comparative evaluation of these data and only standardization will reveal the actual reasons of test variability. The text at hand illustrates that a substantial part of test variability is caused by a misinterpretation of data and/or by the application of different algorithms.
In order to allow the use of standardized evaluation and analysis tools, the European Brake Noise Expert Group developed a standard data exchange format for brake tests, described in guideline VDA 305 (VDA - German Association of the Automotive Industry).
Using the same file format for various test types will create clear data bases for brake development projects. Performance, noise, and other tests will provide important information for all engineers involved in the project.
This paper describes the concept of the VDA 305 definition, comprising all kinds of test results, test data extracts and continuous data recording. It covers all kinds of brake testing - performance and noise dynamometer tests as well as vehicle tests; single brakes up to multiple brakes. There is a detailed description of all involved test material and relevant test parameters (like measuring parameters, signal types, physical units), clearly marked and unambiguous. A scalable and flexible data layout enables the user to a limitation as well as to an extension of the data processing, thus resulting in either a compact overview with substantial test results or an extensive report detailing every single brake application.
By using just one precisely defined data format it will be possible to apply unified methods of analysis and illustration. This workout suggests the use of unified report standards, based on the new data format. Only this will lead to reliable and comparative test results. An expressive example for such a standardized report is, for instance, the “sample report for disc brakes”, which is described in Annex B of the guidelines for the ISO 26867 test procedure. Comparable analyses of test results using this kind of report become clear and reliable if data input matches the VDA 305 guideline. Consequently, this paper now describes a new, unified report standard for brake noise tests (VDA 306) based on data in the VDA 305 format. This new kind of presentation is just a summary of commonly practiced evaluations, although in a unified and clearly defined method. Only by doing this, different test results can be compared in a convincing and meaningful way.