Idle speed control of port‐injection engines via the polynomial equation approach

The design of an idle speed controller for automotive engines is considered. A hybrid nonlinear model of the engine is presented. Based on suitable (nonlinear) change of variables, the idle speed control design problem can satisfactorily be addressed via linear time invariant (LTI) techniques. Specifically, the design problem has been formalized as a finite‐dimensional discrete‐time ∞ optimal control problem, whereby the fuel consumption is minimized. Polynomial techniques have been used to convert the control design formulation to a linear ‘least absolute data fitting’ problem, for which solution very efficient and stable numerical methods exist. Experimental results on a commercial car have been finally reported. Copyright © 2006 John Wiley & Sons, Ltd.