Stochastic simulation and analysis of a classical knock controller

Abstract

Knock control remains a critical issue in modern engine powertrains, and a renewed emphasis on knock as a stochastic process has proved beneficial in the development of new controller designs. However, the random nature of knock also makes it hard to evaluate the closed-loop performance of a knock controller in a rigorous, repeatable way. This work therefore focuses particularly on the statistical properties of knock intensities and knock events, and a new Markovbased analysis is used to compute the corresponding statistical properties and distribution of the closed-loop response. The method is applied to a conventional knock controller, revealing new aspects of its behavior. In particular, the closedloop spark advance distribution is found to be periodic initially, only collapsing to an invariant steady-state distribution as a result of limits applied to the spark advance actuation. The stochastic response of the controller to different initial conditions is also investigated, providing a more rigorous insight into its performance. The results of the Markov-based analysis are confirmed using Monte Carlo simulations.

Cyclic dispersion in engine combustion—Introduction by the special issue editors

“…In contrast to the two previous studies, which focused on control of deterministic sources of cyclic dispersion, Spelina et al 14 …”

“…[14][15][16] Of course, these categories, while convenient, are neither unique nor orthogonal. For the reader's convenience, we also note the mapping of the articles to engine types:…”

“…Conventional spark-ignition (SI) 6,[9][10][11]14 and compression-ignition (CI) (diesel) engines; 7,12 Spray-guided stratified-charge engines; 4,5 Low-temperature combustion (LTC) engines, 8,9,12,13,15,16 including homogeneous charge compression ignition (HCCI) 8,9,15,16 and reactivitycontrolled compression ignition (RCCI). 12,13 In this introductory overview, we place these articles (which include three invited review papers 4,9,10 ) in the larger context of engine research and offer brief but (we hope) tantalizing summaries.…”

Engine knock margin control using in-cylinder pressure data: Preliminary results

“…Under the assumption of stable operation (i.e., knock occurs deterministically at a fixed spark timing), advances and retards cancel each other, and the following equation relates the desired knock probability (P ref ) to the controller parameters (see [15]):…”

Development of a model for the auto-ignition phenomenon in spark ignition engine operating with natural gas

“…To improve the quality of the simulations, Zhen [16] [17] used multi-dimensional analysis and numeric analysis on an engine with high compression ratio and fueled with ethanol, to demonstrate that the EGR, the chamber geometry design and a rich mixture lowers the pressure peaks generated by autodetonation; in the same way, Robert [18] used LES to show the randomness of the detonations (though their locations are possibly associated with the previous ones), and Spelina [19] studied the relationship between the spark advance and the number of cycles of the engine.…”