Integrated Flight/Propulsion Control: Requirements and Issues

Abstract

The integration of flight and propulsion control is an emerging technology that has the potential to offer significant improvements in the mission capabilities of future aircraft systems. Both increased efficiency as well as extended flight and maneuver envelopes have already been demonstrated. There are two main areas of research required to realize fully the benefits of integrating flight and propulsion control. The first is the development of hardware that allows the use of engine air to produce forces and moments about the vehicle axes suitable for high bandwidth attitude control. Thrust vectoring schemes, lift augmentation schemes and direct force/moment control schemes are potential concepts. The second research area is the development of a design approach that will yield integrated control laws.There are several factors which complicate the development of an integrated control design approach. One is that the types of control appropriate for the flight and propulsion systems are fundamentally different and hence global control design approaches may not be practical. Another is that there are a variety of issues such as design accountability that make it desirable to partition the problem. Specifically, control design tasks that relate to airframe safety should be assigned to the airframe manufacturer and those that relate to propulsion to the engine manufacturer.Presented below is an argument that a decentralized-hierarchical design approach is a practical method for designing integrated flight/propulsion control systems. Both the flight control problem and propulsion control problem are reviewed to highlight their differences (emphasis is placed on the propulsion control). Finally, a brief summary is presented of a design approach which is under development and appears to offer a promising solution (the development of this approach was begun under the Air Force DMICS program [1]).