Adaptive internal model control with application to fueling control

This paper presents an adaptive internal model controller for stable but not necessarily minimum-phase SISO plants and its application to the air/fuel ratio control system of a spark-ignited engine. The internal model of the controller is formulated in an output-error structure that can be adapted by using standard adaptive laws. The method is applied to an air/fuel ratio control system with a reduced-order internal model and unknown sensor dynamics. Experiments on an engine test bench demonstrate the capability of the adaptive controller to recover the performance and robustness properties of the control system in the case of an aged oxygen sensor.