Feed-forward observer-based control for estimating cylinder air charge

A method for improving air/fuel ratio control in an internal combustion engine having an electronically controlled throttle valve, the method comprising:

• estimating current and future positions of the throttle valve using a throttle valve position model;
• estimating current and future mass airflow corresponding to the current and future position estimates of the throttle valve, respectively;
• determining a current estimated in-cylinder air charge and a future estimated in-cylinder air charge based on the current and future mass airflow estimates, respectively;
• comparing the current and future estimated in-cylinder air charge to generate a future delta air charge;
• and
• determining a final future estimated air charge based on the future delta air charge.

A system for controlling an internal combustion engine to improve air/fuel ratio control by estimating future in-cylinder air charge, the system comprising:

• an airflow actuator for modulating intake air into the internal combustion engine;
• a mass airflow sensor for measuring mass airflow through an intake passage into the internal combustion engine;
• a position sensor for measuring position of the airflow actuator;
• and
• a controller in communication with the airflow actuator, the mass airflow sensor, and the position sensor, the controller estimating current and future positions of the airflow actuator using an actuator model, adjusting the actuator model based on at least one of the current and future position estimates and a measured position based on a signal provided by the position sensor, estimating current and future mass airflow values corresponding to the current and future position estimates, and combining the difference between the current and future airflow values with a sensed airflow value based on a signal provided by the mass airflow sensor to estimate the future in-cylinder air charge.