Distributed backstepping based control of multiple UAV formation flight subject to time delays

• Published in: IET control theory & applications Vol. 14; no. 12; pp. 1628 - 1638
• Main Authors: Kartal, Yusuf, Subbarao, Kamesh, Gans, Nicholas R, Dogan, Atilla, Lewis, Frank
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 13.08.2020
• Subjects: actual flight test experiments; adaptive control; attitude control; autonomous aerial vehicles; backstepping‐based outer position controller design; cascade control; cascaded control system; centralised formation control; closed loop systems; closed‐loop stability; communication network; control algorithms; control system synthesis; delays; delay‐independent; directed graph; directed graphs; distributed backstepping based control; distributed backstepping structure; distributed control; distributed formation control method; distributed network time delays; inner attitude controller; linear attitude control loop; linear systems; Lyapunov methods; Lyapunov–Krasovskii analysis; mathematical model; mobile robots; multiple UAV formation flight; multiple unmanned aerial vehicles; multi‐robot systems; nonlinear control systems; nonlinear position control loop; position control; propellers; Research Article; stability; stability criteria; stability criterion; distributed network time delays; distributed formation control method; multi-robot systems; centralised formation control; mobile robots; distributed backstepping structure; cascade control; directed graph; attitude control; delay-independent; Lyapunov–Krasovskii analysis; position control; linear attitude control loop; distributed backstepping based control; backstepping-based outer position controller design; stability; actual flight test experiments; multiple UAV formation flight; communication network; distributed control; stability criterion; nonlinear position control loop; control system synthesis; adaptive control; stability criteria; linear systems; control algorithms; multiple unmanned aerial vehicles; closed-loop stability; cascaded control system; closed loop systems; propellers; autonomous aerial vehicles; directed graphs; delays; nonlinear control systems; inner attitude controller; mathematical model; Lyapunov methods
• ISSN: 1751-8644; 1751-8652
• DOI: 10.1049/iet-cta.2019.1151

In this study, the authors propose a backstepping-based, distributed formation control method that is stable independent of time delays in communication among multiple unmanned aerial vehicles (UAVs). Centralised formation control of UAVs requires each agent to maintain a separation distance from other agents, which burdens the communication network of the UAVs. To overcome this problem, the authors consider a distributed control scheme wherein each agent updates its attitude and position based on the state information gathered through its neighbours. Instead of directly controlling the thrust generated by the propellers, they partition the mathematical model of the UAV into two subsystems, a linear attitude control loop and a non-linear position control loop. A backstepping-based outer position controller is then designed that interfaces seamlessly with the inner attitude controller of the cascaded control system. The closed-loop stability is established using a rigorous Lyapunov–Krasovskii analysis under the influence of distributed network time delays. Using the directed graph topology and a distributed backstepping structure, it is shown that the stability criterion is delay-independent. The proposed control algorithms are verified in simulation and then implemented in hardware, and actual flight test experiments prove the validity of these algorithms.