Estimation of Engine Combustion Instabilities for Transient Operation

The contribution of the paper is to propose an estimator of the combustion stability of spark-ignition engines operating in lean-burn conditions. The stability is here taken in the sense of the Coefficient of Variation of the Indicated Mean Effective Pressure. The proposed estimator of the Coefficient of Variation provides in real-time both an estimation of the expected value and of the confidence interval, based on the Bayesian theoretical framework. The estimator only needs a buffer of few measures, making it suitable for transient control. It could lead to the construction of a robust controller in learn-burn conditions, ensuring a better compromise between the engine efficiency and the prevention of combustion instabilities.