By John Rhea
HERNDON, Va. - The next step for full-authority digital engine controls - FADECs, for short - is to manage distributed-control systems for such high-performance future aircraft as the Joint Strike Fighter currently in development, according to Mike Joby, new projects manager at Lucas Aerospace in Herndon, Va.
Electronics and aeronautical engineers originally pioneered FADECs for use in the Concorde supersonic commercial jet aircraft in 1976 to monitor and manage engine performance.
Lucas engineers are working on British government-funded programs in high- performance engine-control systems and integrated flight and propulsion controls. Lucas Aerospace officials are trying to interest the major aircraft engine manufacturers in this technology.
Electronic engine controls (EECs) are the heart of FADEC systems. Although experts consider them to be a great improvement over the hydromechanical and analog electronic systems they replaced, Lucas officials want to go beyond today`s serial digital links.
They want to create a distributed system that will do the processing at the sensor itself and get rid of the central EEC. They would do this autonomously, and Lucas experts maintain this radically different system architecture would improve the meantime between removals for individual control system parts.
First, however, industry scientists need to push the state of the art in two emerging technologies: fuzzy logic and neural networks.
Unlike conventional Boolean logic, which permits only two values such as "on" or "off," fuzzy logic handles concepts of partial truth.
Values can lie between "completely true" and "completely false," according to Lucas experts. Designers can look at circuits within an engine control system as a continuum between "completely on" and "completely off."
Joby says neural networks "may well improve the efficiency of maintenance and trouble shooting. The technique is effective particularly in developing models of the various components of a control system, which can be used diagnostically."
