Flatness-Based Improved Relative Guidance Maneuvers for Commercial Aircraft

Abstract

With the sustained increase of air traffic leading to airspace saturation, new flight maneuvering capabilities are expected for commercial aircraft. Among these, relative guidance of airliners, a set of maneuvers that doesn’t require air traffic control support, appears as a promising solution to ease air traffic controllers’ workload. Relative guidance means path convergence of following aircraft to delayed position of leading ones and station keeping The convergence and station keeping phases are realized onboard the aircraft using their sensing and communication facilities, in a decentralized way, under aircraft maneuverability constraints due to safety and passenger comfort issues. In this paper, after introducing the relative positioning dynamics of two aircraft, their flatness property is shown and a flat control law is proposed. Reference trajectories are designed in two steps: if the separation between aircraft is too small, the follower’s trajectory is stretched by imposing a sinusoidal movement at constant speed; in the opposite case, the follower copies the leader’s delayed trajectory. The feedback tracking is done by feedback linearization. Simulation results, using a real scenario involving wide body aircraft in a merging situation are displayed and discussed.

Keywords: Aircraft control, relative guidance, nonlinear control, differential flatness.