Neural Virtual Sensors - Estimation of Combustion Quality in SI Engines using the Spark Plug

We propose two virtual sensors which estimate the location of the pressure peak and the air-fuel ratio from measurements of the ionization current across the spark plug gap. The location of pressure peak virtual sensor produces estimates on a cycle-by-cycle basis for each of the cylinders. These estimates are twice as good as estimates obtained from a linear model. The air-fuel ratio virtual sensor uses the universal exhaust gas oxygen sensor as reference; it produces estimates that are ten times better than estimates obtained from a linear model. 1 Introduction To optimize the performance and reduce the emission levels of an internal spark ignited (SI) combustion engine one needs measurements of the combustion process quality. These measurements are, e.g., the air-fuel ratio (AFR) and the location of the pressure peak (LPP). The AFR can be used in a feedback control loop as shown in several papers, see [1] and references therein. To achieve optimal performance of the three-way Als..