Model-based idle speed control for a high performance engine

A study, for future applications, of a model-based Idle Speed Control (ISC) system for the L535 Lamborghini 6.2L-48 valve V12 gasoline engine is presented in this paper. Main features of the controller are: Real-time auto-adaptation; Synchronization of Throttle Angle (TA) opening with Spark Advance (SA) timing, through model-based Drive-by-Wire (DBW) control strategies; Auto-adaptive management of the absolute pressure levels in the two, completely separated, intake manifolds; Feed-forward compensation for known loads; Integrated Air-to-Fuel Ratio (AFR) control at idle. Design targets are: Idle speed error from the nominal value imperceptible by the driver, considering that this study is for a high performance engine; Emissions reduction; Minimization of the engine speed undershoot (overshoot) when applying (removing) unknown loads. The controller has been designed by first considering the issues associated with a Lamborghini engine running at idle (comfort in the driver's cabin, exhaust emissions, engine sound, fuel consumption) and by subsequently determining the parameters to meet the design targets. Secondly, a non linear model of the engine-vehicle system has been developed in Matlab-Simulink environment, based on experimental data acquired during both engine bench and on-board tests. Then, the ISC unknown parameters identification was carried out, and finally the controller was implemented in an experimental Electronic Control Unit (ECU) module, and tested in a prototype vehicle. Copyright © 2003 SAE International.