current measuring instrument technologies use software applications in order to determine measured quantity values. The results provided by computer programs are not to be trusted blindly. Their diversity and complexity frequently make such computer programs error-prone. Even comprehensive tests conducted by the manufacturer cannot offer a guarantee that all “errors” have been found. Therefore, it is even more important to validate the software in order to prove that it meets the demands for the application in practice and that all relevant information is displayed completely.
in order that software applications provide a very high level of correct results, several standards demand validation of the applied software:
Extract from DIN EN ISO 9001 [11] or ISO/TS 16949 [23]Chapter 7.6 “Control of monitoring and measuring equipment”
By using computer software for monitoring and measuring specified requirements, the suitability of this software for the intended use must be confirmed. This confirmation must be provided prior to initial use and, where necessary, repeated later on.
Extract from ISO 10012 [12], Chapter 6.2.2 “Software”:
Software used in the measurement processes and calculations of results shall be documented, identified and controlled to ensure suitability for continued use. Software, and any revision to it, shall be tested and/or validated prior to initial use, approved for use and archived.
The typical range of the various computer programs used for monitoring and measuring specified requirements include measurement and evaluation programs for:
- coordinate measuring machines
- measuring forms and surfaces
- measuring systems / SPC systems
- test benches
- statistical evaluations
The demands on computer programs apply to third-party software and to the corporate software. A standardized procedure is recommended for an efficient validation. The validation shall be documented by means of an individual checklist. This list shall contain a reference to the following tasks, for example:
- Compare release number on data storage medium to manual information.
- Document individual configuration and settings of the software.
- Check important functions (to be specified for each respective application) after installation is completed.
- Take measurements on calibrated reference standards and compare results to the calculated actual values and to the results of the previous version (also considering measurement uncertainty).
- Check whether all relevant information is provided.
- Compare results (e.g. obtained from multiple point measuring instrument) with more precise measuring system (e.g. coordinate measuring machine in measuring laboratory).
- In order to make an evaluation, test data shall be provided with known results. This data is loaded, recalculted and the results are compared to the results of references.
After completing the vaildation successfully:
- approve the program explicitly for use.
- Replace/update all installed systems concerned (if possible via network in order not to miss any individual system).
- inform the users concerned about the latest software version.
- sign a software maintenance contract, if possible, in order to be informed about any future upgrades (e.g. new guidelines, standards and legal regulations) automatically.
Naturally, software is not subject to wear. For this reason, no further inspections of the validated software are required while it is used. However,the software must be validated again when changes in the system environment or to any signficant charcateristics of the software, hardware or the operating system take place. Ideally, the software producer / supplier provides a certificate of qualification (expert opinion)
reference :VDA
