Affiliations: Intelligent Systems & Signal Processing
Laboratories, Engineering Research Centre, University of Brighton, Moulsecoomb,
Brighton, BN2 4GJ, UK
Abstract: Small spark-ignition gasoline-fuelled internal-combustion engines
can be found all over the world performing in various roles including power
generation, agricultural applications and motive power for small boats. To
attain low cost, these engines are typically air-cooled, use simple
carburettors to regulate the fuel supply, and employ magneto ignition systems.
Electronic control, of the sort found in automotive engines, has seldom proved
cost-effective for use with small engines. However, the future trend towards
engines that have low levels of polluting exhaust emissions will make
electronic control necessary, even for small engines. This paper describes a
fuzzy control system applied to a small engine to achieve regulation of the
fuel injection system. The system determines the amount of fuel required by a
fuzzy algorithm that uses the engine speed and manifold air pressure as input
values. The parameters of this fuzzy control paradigm were a collection of
rules and fuzzy-set membership functions. These were intuitively comprehensible
by the operator. This facilitated the calibration process, leading to quick and
convenient tuning. Experimental results show that a considerable improvement in
fuel regulation was achieved compared to the original carburettor-based engine
configuration. In addition measurements of HC and CO emissions show a
corresponding reduction.
