Systematic Model-Based Engine Control Design

The present paper describes the development of a comprehensive engine control strategy for a 5.7 Liter eight cylinder engine with dual exhaust system. The control strategy is torque-based and distinguishes two essential control modes, engine speed control under idle engine operation and torque (load) control under normal engine operation. The controller synthesis is carried out within the context of a thoroughly model-based design paradigm. It involves the synthesis of one distinct multi-variable feedback controller for each of the two control modes. A particular focus is on synthesizing robust feedback-controllers that require very little experimental calibration. To this end, multi-variable H_∞ design principles are applied. The linear models underlying the controller synthesis are derived from an accurate nonlinear engine model. The fully integrated controller is experimentally validated on a test vehicle equipped with a custom-made, full-authority controller prototyping system. Experimental tests are carried out on a vehicle dynamometer and involve the first 18 cycles of the FTP test procedure (Urban Dynamometer Driving Schedule). The results confirm that the model-based engine control design approach proposed in this paper is indeed a viable approach and bears potential for significant cost and time savings without sacrificing control performance.