IDENTIFICATION AND AIR-FUEL RATIO CONTROL OF A SPARK-IGNITION ENGINE

Accurate control of the air-fuel ratio in a spark-ignition engine is c ritical to satisfying future federal and California emissions regulati ons. The goal of this research is to explore the use of adaptive contr ol as a means of precisely controlling the air-fuel ratio, A control-o riented, physics-based engine model, in which the sampling rate is bas ed on crank-angle instead of time, has been utilized to construct a fe edforward/feedback control scheme to regulate air-fuel ratio, The deri ved control law, however, requires the values of time constants, delay times, and other model parameters that must be experimentally determi ned, Since these parameters can possibly change over time, a method fo r estimating them on-line is preferred, A nonlinear least squares iden tification technique is used to accurately determine the model paramet ers using normal engine operating data, These parameter values are the n employed in an estimator based controller to demonstrate cycle-to-cy cle air-fuel ratio regulation on a single-cylinder laboratory engine ( CFR) during various throttle transients.