Inverse adaptive air-fuel ratio control in spark ignition engines

The problem of air-fuel ratio (AFR) stabilization at the stoichiometric level is addressed in the paper. Two solutions of this problem based on the inverse dynamics principle are proposed. The first one consists in building empirical model of the engine, its on-line identification and further inversion. The second approach assumes building inverse model of the engine initially and then its identification. The both models — direct and inverse — are presented by grey boxes with physically-inspired input functions and structures. The models are used for the derivation of two feedforward controls with the parameters tuned online. The feedforwards with the estimated parameters provide the compensation of plant uncertainties, nonlinear dynamics and the delay of AFR measurement.