Identification of a thermodynamic model for spark ignited internal combustion engines

A classical air-cycle thermodynamic combustion model for cylinder pressure in an internal combustion engine is recast into a certain state space form in which pressure evolves according to a linear time varying difference equation. Model parameter identification from observation of cylinder pressure data via maximum likelihood is shown to have a simple form which may permit on-line implementation. Experimental demonstration of the method is provided using data from a one-cylinder CFR research engine.