A Sliding Mode Observer for a Typical Diesel Engine Particulate Aftertreatment System

A differential-algebraic system model for a typical diesel engine particulate aftertreatment system, which consists of exhaust pipes, a fuel burner for active soot regeneration control and a diesel particulate filter (DPF), is introduced. The model is developed based on control volume method and has features of nonlinear and high-index. The model is realized using a singularly perturbed sliding manifold (SPSM) approach, and system parameters are verified using experimental data. The stability and observability of linearized model are discussed. The original system model is transformed into a normal control form for which a sliding mode observer (SMO) is designed. An example application of the SMO on the aftertreatment system is demonstrated and results are compared with that of a Luenberger-like pole placement observer.