Self Tuning Optimisation Of Spark Ignition Automotive Engines

The paper describes the use of self-tuning control concepts applied to the adaptive optimisation of spark ignition angle of an automotive engine. In particular, it is shown how the control theory concepts of self-adaptive control can be modified in a manner which allows their use in continuously up-dating the map of spark angle as a function of load and speed. Used in this way, the self tuner can account for in-service changes in engine characteristics, changes due to ambient changes and changes in operational conditions. In addition, self-adaption allows the spark controller algorithm to tune itself such that the factory-generated spark map is precisely matched to the exact nature of each individual engine. The paper outlines the basic theory of self-tuning optimisers (also known as extremum controllers) and discusses their performance features with particular reference to their implementation in adaptive spark timing systems. It is shown that the self tuning extremum controller can be made robust even when the signal to noise ratio is less than one.