ASAM MCD-2 CERP is an extension of the ISO OTX standard (ISO 13209), which defines functions to describe calibration parameter dependencies. The current version covers the use-case of calibration parameter checking. The standard may be extended in the future to include the use-case of calibration parameter calculation. Tools, which cover such use-cases, are broadly named "Calibration Expert Systems".
The standard is an attempt to solve the problem of the steadily growing number of calibration parameters in ECU software and their variants. What turns out as an even bigger problem is that the parameter dependencies and variants become increasingly more enmeshed and complex. Ensuring that there are no contradictions and violations of (written or unwritten) rules within the calibration data set of an ECU becomes a task that can not be handled via reviews and the calibration expert's "attention" alone any longer. Some OEMs and ECU supplier companies started to develop in-house tools, which allow to automate the task of calibration parameter checking.
ASAM MCD-2 CERP provides a standardized way for defining calibration parameter dependency rules. The standard has functions for access to database information (according to ASAM MCD-2 MC), calibration runtime data (values, units) and the product model exchange file. Additionally, sophisticated check functions and procedures are defined to compare and validate data. The standard includes a product model that describes properties and features of the system, which are not calibration parameters in the ECU, such as the number of cylinders or the emission law to which the vehicle has to comply with. Since OTX can be considered as a programming language that is Turing-complete, it is possible to write arbitrary check routines including branches, loops, conditions and mathematical calculations. This allows software engineers and calibration experts to write check scripts that formalize empiric calibration knowledge and relevant information about the control loop, software and hardware design. This expert knowledge is then used to validate calibration data. The result of a check routine consists of a status, messages and the severity of detected problems.
The standard allows that calibration parameter checking rules can be expressed in a formalized language, their execution can be automated and can be freely exchanged between the OEM, its ECU suppliers and other involved parties in the ECU development process. Issues with calibration parameters can be found early on in the development process, saving significant time and money.