NASA is refining an on-line, self learning "intelligent" flight control system (IFCS), following flight tests of a preliminary version at Dryden Flight Research Center, Edwards AFB, California, on the agency's Boeing F-15 Eagle testbed. The smart software is being developed to enable pilots to land safely damaged aircraft that would otherwise be uncontrollable.
IFCS uses experimental "neural network" software that "learns" to fly the aircraft by observing patterns in the data it receives and processes. The aim is to develop an IFCS which will be a full on-line self-learning system able to manage significant configuration changes, including major battle damage, and compensate automatically to help the pilot maintain control. NASA also envisages an IFCS for commercial airliners.
The flight trials were made using neural network software "pre-trained" to the F-15's aerodynamic database. Using an adaptive controller already installed in the testbed, the software was tested throughout part of the flight envelope from 16,000ft (4,850m)to 34,000ft and Mach 0.6 to 1.2. Manoeuvres included simple pitch and roll doublets, as well as angle-of-attack and sideslip motions. A total of 15 flights was made over four weeks, the last on 23 April.
NASA says that "overall, it operated extremely well, although in the pitch mode it overshot a bit". It adds that some pilots considered it "a bit sloppy", but the comparison is relative as the test aircraft is "much better than a conventional F-15", NASA says.
The software identified the aircraft's stability and control characteristics, and immediately adjusted the control system to maintain the best flight performance.
Data from the aircraft's sensors was compared with the predicted pattern (based on pre-programmed control laws). If a mismatch was detected, due to either equipment failure or damage, the flight control computer used the software to "relearn" to fly the aircraft six times every second.
NASA hopes that development of the IFCS, originally devised in conjunction with Boeing's Phantom Works, will enable instant reconfiguration, making any flight control surface failure virtually transparent to the pilot.
Source: Flight International
