This paper presents an original methodology for the instantaneous in-cylinder pressure waveform reconstruction in a spark-ignited internal combustion engine. The methodology is based on the existence of a linear correlation, characterized by frequency response functions, between in-cylinder pressure and engine speed signals. This correlation is experimentally verified and evaluated by simultaneous measurements of the above-mentioned quantities. The evaluation of different frequency response functions, one for each steady-state condition investigated, allows recovering the pressure waveform even under other engine running conditions (i.e., transients). In this way, during on-board operation, the pressure waveform could be recovered using only the engine speed signal, already present in current production electronic control units. In this paper the signal processing methodology and some experimental results, obtained during transient tests, are presented. The methodology could be interesting for the development of advanced engine control strategies aimed at the management of the torque generated by the engine. As an example, traction control in drive-by-wire systems could be a possible challenging application. The in-cylinder pressure reconstruction performed using the frequency response functions, in fact, allows the evaluation of the indicated torque. An important characteristic of this methodology is, furthermore, the diagnostic capability for the combustion process, that is guaranteed by the linear correlation between in-cylinder pressure and instantaneous engine speed waveforms. Also in presence of a misfiring cylinder, when the instantaneous engine speed waveform is strongly affected by the absence of combustion, the reconstructed in-cylinder pressure shows a good agreement with the measured one. The experimental tests have been conducted in a test cell using a four-cylinder production engine. It has to be noted, anyway, that the same methodology can be applied to engines with a higher number of cylinders.

Azzoni, P., Moro, D., Ponti, F., and Rizzoni, G., “Engine and Load Torque Estimation with Application to Electronic Throttle Control,” SAE Technical Paper No. 980795.
Citron, S. J., O’Higgins, J. E., and Chen, L. Y., “Cylinder by Cylinder Engine Pressure and Pressure Torque Waveform Determination Utilizing Speed Fluctuations,” SAE Technical Paper No. 890486.
, and
J. J.
, “
Nonlinear Diesel Engine Control and Cylinder Pressure Estimation
ASME J. Dyn. Syst., Meas., Control
, No. 2.
Shiao, Y., and Moskwa, J. J., “Misfire Detection and Cylinder Pressure Reconstruction for SI Engines,” SAE Technical Paper No. 940144.
Cavina, N., Ponti, F., and Rizzoni, G., “Fast Algorithm for On-Board Torque Estimation,” SAE Technical Paper No. 1999-01-0541.
Wakuri, Y., Soejima, M., Ejima, Y., Hamatake, T., and Kitahara, T., “Studies on Friction Characteristics of Reciprocating Engines,” SAE Technical Paper No. 952471.
Arsie, I., Pianese, C., Rizzo, G., Flora, R., and Serra, G., “Development and Validation of a Model for Mechanical Efficiency in a Spark Ignition Engine,” SAE Technical Paper 1999-01-0905.
Gassenfeit, E. H., and Powell, J. D., “Algorithms for Air-Fuel Ratio Estimation Using Internal Combustion Engine Cylinder Pressure,” SAE Technical Paper No. 890300.
Randolph, A., “Methods of Processing Cylinder-Pressure Transducer Signals to Maximize Data Accuracy,” Paper No. SAE 900170.
Moskwa, J., Wang, W., and Bucheger, D. J., 1998, “A New Methodology for Engine Diagnostics and Control Utilizing “Synthetic” Engine Variables: Theoretical and Experimental Results, Proceedings of the ASME, Dynamic Systems and Control Division, DSC-Vol. 64, ASME, New York.
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