Inverse-NARMA: a robust control method applied to SI engine idle-speed regulation

Abstract

This paper presents a control technique based on a directly identified non-linear inverse of a stable system. A NARMA model of the inverse of the uncontrolled system is identified using reversed input–output data collected experimentally from the plant. Linear identification is carried out on the plant which is pre-compensated by the identified inverse, sufficiently time delayed to be causal. This achieves a reduction in the uncertainty representation necessary to model the non-linearity. Subsequent robust linear controller design results in an improvement in robust performance when using the inverse pre-compensator. The method is applied to the automotive SI engine idle-speed control problem using a parameter space linear robust control design technique. The result is experimentally validated using an electric dynamometer.