Coordinated Path Following Control of Fixed-wing Unmanned Aerial Vehicles

TL;DR

This paper presents a hybrid control law enabling fixed-wing UAVs to follow paths in 2D while respecting speed constraints, ensuring coordinated inter-UAV distances and convergence of path errors through theoretical proof and simulation.

Contribution

The paper introduces a novel hybrid control approach that manages fixed-wing UAVs' speed constraints for coordinated path following, with proven convergence and validated in hardware-in-the-loop simulations.

Findings

Control law achieves zero path following error within invariant set

Desired inter-UAV arc distances are maintained and converge

Method is validated through MATLAB and real hardware-in-the-loop tests

Abstract

In this paper, we investigate the problem of coordinated path following for fixed-wing UAVs with speed constraints in 2D plane. The objective is to steer a fleet of UAVs along the path(s) while achieving the desired sequenced inter-UAV arc distance. In contrast to the previous coordinated path following studies, we are able through our proposed hybrid control law to deal with the forward speed and the angular speed constraints of fixed-wing UAVs. More specifically, the hybrid control law makes all the UAVs work at two different levels: those UAVs whose path following errors are within an invariant set (i.e., the designed coordination set) work at the coordination level; and the other UAVs work at the single-agent level. At the coordination level, we prove that even with speed constraints, the proposed control law can make sure the path following errors reduce to zero, while the desired arc distances converge to the desired value. At the single-agent level, the convergence analysis for the path following error entering the coordination set is provided. We develop a hardware-in-the-loop simulation testbed of the multi-UAV system by using actual autopilots and the X-Plane simulator. The effectiveness of the proposed approach is corroborated with both MATLAB and the testbed.