Performance Assessment of Knock Control Systems Subject to Disturbances

• Published in: SAE International journal of engines Vol. 14; no. 6; pp. 821 - 832
• Main Authors: Jones, James Peyton, Frey, Jesse
• Format: Journal Article
• Language: English
• Published: Warrendale SAE International 01.01.2021; SAE International, a Pennsylvania Not-for Profit
• Subjects: Calibration; Control; Control systems; Control systems design; Controllers; Cost function; Disturbances; Knock; Performance Assessment; Properties; Statistical methods; Stochastic; Transient response; United States
• ISSN: 1946-3936; 1946-3944; 1946-3944
• DOI: 10.4271/03-14-06-0049

Rigorous assessment of knock control systems is complicated by the fact that single experiments or simulations give results that are nonrepeatable due to the random arrival of knock events. Assessment of the closed-loop transient response to disturbances, in particular, is often very limited but this is critical for effective controller design and calibration. In this study, recent methods to estimate the statistical properties of the closed-loop response are extended to include the effects of random disturbances in order to excite and quantify both the transient and steady-state performance of the controller. A variety of assessment metrics are developed as well as a new cost function that embeds both the increased knock risk as the spark is advanced, and the cost of lower engine efficiency and Indicated Mean Effective Pressure (IMEP) as the spark is retarded. The new method and metrics are applied to compare different controller calibrations and different knock threshold definitions, with and without randomly applied disturbances. The results highlight the importance of considering disturbances in the analysis and also the effectiveness of knock threshold calibration.