Estimation of Within Cycle Dynamics of an SI Gasoline Engine Using Equivalent Cycle Reconstruction

In this paper, a novel method is presented for estimating the repetitive high frequency within cycle dynamics of spark ignition (SI) gasoline engines using equivalent cycles of data reconstructed from low rate uniformly time-sampled measurements. The process of equivalent cycle reconstruction using phase information of samples obviates the need for extra sampling hardware, usually associated with equivalent time sampling in digital oscilloscope applications. The reconstructed equivalent cycle measurements, obtained from low rate sampled data can be used in a state estimator, which uses high frequency within cycle SI gasoline engine model. Results of estimation based on engine data using an industry standard simulator confirm that it is possible to faithfully track states evolving under the within cycle dynamics, which are repetitive using data initially acquired at sampling rate well below Nyquist rates. To the best of the authors' knowledge, this is the first report in the literature on estimation of the within cycle dynamics of automobile engines using engine measurements, acquired at a low frequency well below the Nyquist rates.