Adaptive and Unconventional Strategies for Engine Knock Control

Knock is an undesirable phenomenon affecting the gasoline spark-ignition (SI) engines. In order to maximize the engine efficiency and output torque while limiting the knock rate, the spark timing should be adequately controlled. This brief focuses on the closed-loop knock control strategies. The proposed control strategies, compared with conventional approaches, show improved performances while remaining simple to use, implement, and tune. First, a deterministic controller that employs a logarithmic increase of the spark timing proves to outperform the conventional strategy in terms of spark timing average and variance. In addition, an adaptive parameter strategy that exploits stochastic information of the process is introduced. Thanks to this extension, the average and the variance of the spark timing are additionally improved while preserving the ease of tuning and the fast reaction times of the deterministic strategy. Throughout this brief, all the knock controllers are compared with a conventional deterministic strategy and with a recently proposed stochastic one. The advantages of the proposed approaches are confirmed both by simulation and by experimental data collected at a test bench.