A comparison of intelligent, adaptive, and nonlinear flight control laws is the topic of a paper recently published in proceedings of the American Institute of Aeronautics and Astronautics (AIAA).
Written by ONR-funded researcher Marc Steinberg, the paper examines seven different nonlinear control laws for multi-axis control of a high-performance aircraft. Steinberg's research is important to the U.S. Navy because adaptive and intelligent flight control may someday allow battle-damaged aircraft that would otherwise be lost, to safely disengage from combat and return to friendly skies.
In peacetime operations, adaptive and intelligent flight control could save aircraft that might otherwise be lost due to midair collision damage or component failure. Steinberg also reports that commercial "fly-by-wire" aircraft such as the Boeing 777 could benefit from this type of control.
Nonlinear control approaches have seldom been used on aircraft, although many research efforts have produced simulation results. Despite a body of work, it can be difficult to judge the relative value of different nonlinear control approaches for any specific flight control problem.
Nonlinear controllers have been known to demonstrate spectacular results on simplified aircraft models but display pathological responses when applied to higher fidelity simulation models. While no "winners" or "losers" were identified in the paper, it does provide a scientifically sound comparison and evaluation of new, nonlinear control laws.