Control-oriented observer for cylinder pressure estimation of SI engine using frequency response function

This paper presents a closed-loop control-oriented observer (COB) for in-cylinder pressure estimation, which utilises a one zone combustion model in the feed-forward loop and frequency response function (FRF) model in the feedback loop. The model uses the phase difference in firing frequency of crankshaft speed as a measure to update COB parameters. The update rate of control parameters in the COB is one engine cycle. The COB is found observable at the top dead centre (TDC). The applicability of the proposed model is illustrated by simulation and experimental results. Further, a comparative study using closed-loop COB, FRF, and sliding mode observer (SMO) methods, is also presented.