In recent years, due to more and more stringent government
regulations on diesel emissions, diesel aftertreatment systems have
attracted great deal of attention from both academia and diesel
engine industries. Many different devices and approaches, such as
Urea SCR, LNT, engine control related EGR and in-cylinder post
injection, have been developed and applied to reduce nitrogen
oxides (NOx) emissions. Among those solutions, Lean
NOx Trap (LNT)-based emission reduction control system
is one of the common approaches.
The NOx storage capacity of an LNT depends on many
different factors and operating conditions. Accurate and real-time
estimation of NOx storage is quite important for
efficient system controls, particularly for enhancing system
lifespan and reducing overall fuel consumption. A more precise
modeling of NOx storage has more significant impact for
overall system performance. In this paper, we will discuss a few
linear system models, and extend the results into a new approach
for LNT NOx storage estimation by using system
identification of a nonlinear autoregressive with exogenous input
(NARX) model. Adaptation and on-line training features are also
proposed, and experimental data have been used for validation and
verification of the methodology.