Powertrain Control

Accelerated Engine Mapping and Optimization

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With the increased number of subsystems in place, it was difficult to make a simple one-to-one association between actuators and performance measures; e.g., VGT duty cycle controls boost pressure and hence smoke production. The usual performance measures included fuel consumption and emission of such regulated substances as oxides of nitrogen and smoke.

 

Control Engineer's Perspective

It is important that the cross-coupling between actuators and performance measures be characterized (mapped). While such characterization is important in itself, it is but a step toward the final goal of determining setpoints for various actuators to achieve overall performance that is optimal in some sense.

 

For example, the goal might be to achieve good fuel economy while limiting the production of regulated substances.

 

Curse of Dimensionality

The traditional full-factorial method for mapping and optimization can be shown to require years worth of effort for a modern engine—a proposition impractical both from the time and cost points of view.

 

SwRI has invested internal funding resources to explore possible ways to reduce the time and cost required to optimize actuators. Along with elements of Design of Experiments (DOE), the approach recognizes and exploits time-scale separation in the engine system dynamics. Optimal settings are parameterized by “slow” system states. Preliminary results of this investigation are very promising.