Close formation flight control

Abstract

In this paper the close formation flight control problem is addressed. The formation consists of a lead and wing aircraft, where the wing flies in close formation with the lead, such that the lead's vortices produce aerodynamic coupling effects, and a reduction in the formation's drag is achieved. A controller, i.e., a formation-hold autopilot for the wing aircraft, is designed such that the formation's geometry is maintained in the face of lead aircraft maneuvers. In the formation flight control system, the wing and lead aircraft dynamics are coupled due to kinematic effects, and, in the case of close formations, additional aerodynamic coupling effects are introduced. In the paper these additional aerodynamic coupling effects are properly modeled. The most significant aerodynamic coupling effect introduced by close formation flight entails the coupling of the lateral/directional channel into the altitude-hold autopilot channel. It is shown that formation hold autopilots designed ignoring the aerodynamic coupling effects yield satisfactory performance in close formation flight.

Adaptive Backstepping Flight Control for Modern Fighter Aircraft

“…Inertial trajectory control is essential for these UAVs, since they are usually required to follow predetermined paths through certain target points in the threedimensional air space [29,96,97,151,171,172,184]. Other situations where trajectory control is desired include formation control, aerial refueling and autonomous landing maneuvers [68,155,156,168,182,207]. This has lead to a lot of literature dedicated to formation and flight path control for UAVs, but also for other types of (un)manned vehicles [80,146].…”

“…7.3 where a new rotating reference frame for control, that is fixed to the aircraft and aligned with the horizontal component of the velocity vector, is introduced [168,172]. Differentiating (7.12) givesŻ…”

Full Capability Formation Flight Control

“…The above coefficients are taken from Morgan's work and presented as a function of the lateral spacing only. This is a fairly good assumption for our purposes since we are looking to see controller performance with the worse case disturbance values and not trying to predict fuel savings or lift and drag changes as in previous work (15,7,8,20,10).…”

“…With the above separation dynamics equations (36-38), and the single ship wind axes equations of motion (14)(15)(16)(17) all written in terms of the aerodynamic force values of lead and wing, the two aircraft system model can be developed.…”

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