Observer-based air fuel ratio control

This paper discusses the application of linear observer theory to engine control with a specific focus on observers based on exhaust measurements. The motivation for this architecture is that a direct measurement of the relevant quantity (the exhaust chemistry entering the catalyst) will typically lead to the most accurate control. A secondary motivation is the need to reduce costs. If sufficient accuracy can be obtained with the exhaust sensor providing the primary information, the cost associated with intake manifold sensors can be reduced. The basic theory is discussed and experimental results are reported that illustrate the benefits and superior performance of linear observer based control.