Modeling of Air-Fuel Ratio Dynamics of Gasoline Combustion Engine With ARX Network

This article deals with nonlinear modeling of air-fuel ratio (AFR) dynamics of gasoline engines during transient operation. With a collection of input-output data measured near several operating points of the commercial engine, we have identified a global model of the system. The global model structure comes out of the modeling principles based on a weighting of local linear ARX model parameters in dependency on the operating point. It was found that the studied global model has the ability to approximate nonlinear effects and varying response time as well as varying time delay of air-fuel ratio dynamics. The advantage of the local linear approach is that it is flexible to fit experimental data and provides an appropriate structure for advanced nonlinear control algorithm synthesis. Moreover, the proposed nonlinear AFR model with identified numeric values of parameters listed in this article can be used for simulation purposes and also for testing of control algorithms.