Optimal Lambda Control

The Task

Test the diagnosis capabilities of a lambda-based exhaust aftertreatment control system.

The Challenge

As part of the onboard diagnostics (OBD) system, the lambda sensor output in the engine’s exhaust path underlies different diagnosis routines, which have to be validated in a HIL environment. Several chemical reactions have to be considered in a three-way-catalyst system, and the detailed simulation of all related effects drastically increases the calculation time and parameterization effort. Therefore, the dominant effects for testing OBD-relevant ECU functions must be identified, while taking into consideration the data sources available to the user to provide a real- time-capable solution that is ready for use in HIL projects.

The Solution

The three-way-catalyst simulation from ASM considers the effects correlated to the oxygen storage capacity of the aftertreatment component as well as effects based on backward reactions within the catalyst itself. Prior knowledge on the chemical reactions and relevant effects is used to develop a phenomenological modeling approach based on oxygen storage and release rates within the catalyst to generate a lambda sensor output signal that captures effects used in the diagnosis system to identify aging aftertreatment systems, for example.