Individual Cylinder Air-Fuel Ratio Feedback Control Using an Observer

In this research project, modeling of the dynamic air excess ratio (λ) behavior in the exhaust gas at the confluence point in the exhaust manifold was performed. By applying an observer which is one method described by modern control system theory, estimation of the λ for each cylinder was carried out using one λ sensor. The estimated value was used to perform λ feedback control for each cylinder, allowing compensation of deviation in air-fuel ratio between cylinders and individual control of fuel injection volume for each cylinder, dramatically enhancing λ controllability.