SYSTEM AND METHOD FOR ADAPTIVE CONTROL OF AIR-TO-FUEL RATIO

An air-fuel ratio control system includes an internal combustion engine configured to combust gaseous fuel, an admission value configured to provide gaseous fuel to the internal combustion engine, and a three-way catalyst connected to the internal combustion engine to receive exhaust formed by combustion of the gaseous fuel with the internal combustion engine. The system also includes a sensor connected upstream or downstream of the three-way catalyst and a controller configured to: generate commands for controlling the admission valve, receive oxygen content signals or NOx content signals output from the sensor, and determine, with a perturbation-based control algorithm and based on the oxygen content signals or NOx content signals, commands for controlling an air-fuel ratio of the internal combustion engine, including commands for controlling the admission valve.