Idle speed control using a describing-function approach

A new systematic method for idle speed control of uncertain automobile engines with a time delay is developed. The method is based on obtaining a describing-function model of the internal combustion engine. This is followed by designing a classical controller via an algebraic approach. The design method and the associated software are applied to a specific automobile engine, and it is shown that the results compete with the observer-based design of Bengea et al. Stability is demonstrated by successful generation of describing-function models of the final non-linear closed-loop system.