Virtual sensing gets real

As emissions regulations get more strict, emissions measurement must get more precise for onboard diagnostics, engine control, and model-based controller design.

Particulate matter and nitrogen oxides (NOx) are the most demanding pollutants for diesel engine manufactures to address. The legislation limits can be met either by in-cylinder measures like exhaust gas recirculation (EGR) and multiple fuel injections or by the use of aftertreatment devices like selective catalytic reduction (SCR) or lean NOx traps (LNT).

For onboard diagnosis as well as for control of these systems the value of the NOx raw emissions is essential. Thus, precise engine control depends on the availability of sensors that are reliable, robust, immune to noise, and have the capacity to operate in harsh off-highway environments.