Formation Control of Swarms of Unmanned Aerial Vehicles

The objective of this doctoral thesis [1] is to design a distributed formation control system for swarms of unmanned aerial vehicles which addresses the challenges of scalability, collision avoidance, failure recovery, energy efficiency, and control performance. The swarms are arranged in tightly/loosely coupled architectures, which are based on homogeneous nodes in a distributed network of leader-follower/leaderless structures. The model of each node in the swarm formation is based on the nonlinear/linear dynamic model of a quadcopter, i.e. an unmanned aerial vehicle. The goal is to design the formation control of swarms of unmanned aerial vehicles, which is divided into high- and low-level control. From the high-level control perspective, the main contribution is to propose continuous path planning which can quickly react to events. Setpoints are generated for the swarms of unmanned aerial vehicles considering the complex movement of a hierarchical formation, soft landing, and failure recovery. The hierarchical formation and soft landing are executed using a fixed formation. Reconfiguration of the formation after node failures is implemented using a shortest path algorithm, combinatorial algorithms, and a thin plate spline. Besides this, from the low-level control perspective, the main contribution is to manoeuvre the nodes smoothly. The tracking of setpoints and stabilisation of each node is handled by a nonlinear sliding mode control with proportional derivative control and a linear quadratic regulator with integral action. The proposed strategies are evaluated using simulations, and the obtained results are compared and analysed both qualitatively and quantitatively using different scenario-relevant metrics. In addition, this doctoral thesis (Anam Tahir. Formation Control of Swarms of Unmanned Aerial Vehicles. Doctoral Dissertation, University of Turku, Turku, Finland, September 2023, ISBN: 978-951-29-9411-3. Available: https://urn.fi/URN:ISBN:978-951-29-9411-3) includes the five publications: (I) Anam Tahir et al., "Swarms of Unmanned Aerial Vehicles — A Survey", Journal of Industrial Information Integration, vol. 16 (100106), pp. 1-7, 2019, doi: 10.1016/j.jii.2019.100106. (II) Anam Tahir et al., "Comparison of Linear and Nonlinear Methods for Distributed Control of a Hierarchical Formation of UAVs," IEEE Access, vol. 8, pp. 95667-95680, 2020, doi: 10.1109/ACCESS.2020.2988773. (III) Anam Tahir et al., "Navigation System For Landing A Swarm Of Autonomous Drones On A Movable Surface", 34th International ECMS Conference on Modelling and Simulation, Proceedings of the Communications of the ECMS, Wildau, Germany, Volume 34, Issue 1, pp. 168–174, 2020, doi: 10.7148/2020-0168. (IV) Anam Tahir et al., "Development of a Fault-Tolerant Control System for a Swarm of Drones", 62nd International Symposium ELMAR, IEEE Proceedings, pp. 79–82, Zadar, Croatia, 2020, doi: 10.1109/ELMAR49956.2020.9219027. (V) Anam Tahir et al., "Energy-Efficient Post-Failure Reconfiguration of Swarms of Unmanned Aerial Vehicles," IEEE Access, vol. 11, pp. 24768-24779, 2023, doi: 10.1109/ACCESS.2022.3181244.