Nonlinear air-fuel ratio predictive control of spark ignited engines

The aim of this paper is to present a nonlinear model-based predictive control (NMPC) for air-fuel ratio (AFR) of spark ignited (SI) engines. Complexity of NMPC implementation causes that the computational requirements on storage space and online computation time have to be considered in the controller design. Especially a limitation on computation time makes often the optimal control law too complex to be implemented and some suboptimal solution has to be provided to meet the requirements. The point of the paper is to present the controller which utilizes the simplified control problem in a warm-start technique and allows to decrease the online computational effort caused by the nonlinear predictive controller.