In engine development, the ‘mapping’ task involves producing tables and models, which define an engine's operating characteristics. Complicated engines with multiple continuously variable valvetrain mechanisms, variable compression ratio or stratified direct injection become increasingly difficult and time consuming to characterise as the number of degrees of freedom rise.
‘Model Based Calibration” tools have been developed by various companies which use Design of Experiment (DoE) techniques to improve data quality and reduce testing time.
This paper describes work carried out to determine the practical advantages and limitations of different tools when applied to a high degree of freedom characterization and optimization task.
The conclusions will indicate that the model-based/DoE techniques are powerful tools in many situations but require careful application to stratified engines in particular. Defining the region of stable operation is a crucial task that is not well covered by existing tools. Possible solutions to this problem will be discussed.