# Design of an Autonomous Cooperative Drone Swarm for Inspections of Safety Critical Infrastructure
## 9 Conclusions  
Inspection of critical infrastructure with a swarm of drones is an attractive innovation made possible with recent advances in electronics, communication, and computer technology. The European research and innovation project Drones4 Safety (D4S) targets an increase in the safety of civil transport networks by designing a system of autonomous and cooperative drones for autonomous and continuous inspection. In this paper, we have reported on the design of a UAS to support safety-critical infrastructure inspections.  
Drones are equipped with an onboard Multiprocessor System on a Chip (MPSoC) to enhance processing capabilities. Cameras and mmWave radar sensors are added to the drone system to improve navigation close to inspection objects. The software platform is based on ROS and provides low-level and high-level control parts of the drone. The inspection application interacts with the high-level control system to support algorithms including cable detection and identification, motion path planning, obstacle avoidance, formation flying, object and fault detection with AI, and swarm membership management. Drone-to-Drone (D2D) communication is used for cooperative functions and to support a high data rate wireless mesh with ranges of a few hundred meters. Drone-to-Ground (D2G) communication is used for telemetry reporting and is based on long-range wireless communication using LoRa. The drone swarm is loosely connected to a set of supporting Cloud Services using Drone-to-Cloud (D2C) communication offering internet access. The Cloud Services support autonomous inspection from a mission control point of view. Functions such as planning, monitoring, storage, and analysis services are key parts of this operational support. Cloud Services provide the interface between a remote human supervisor and the cooperative drone swarm.  
Despite its large complexity, we find that the design of an autonomous cooperative drone swarm for critical infrastructure inspection is feasible given the current state of the art in electronic components, software, and communication technology. To raise the technology readiness level of our proposed autonomous drone swarm further, we will, in future work, focus on the robustness, durability, and scaling of the UAS. In addition, more emphasis will be put on the operational aspects, including compliance with European UAS traffic management system (UTM) services.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13031256/s1](https://www.mdpi.com/article/10.3390/app13031256/s1)]([https://www.mdpi.com/article/10.3390/app13031256/s1](https://www.mdpi.com/article/10.3390/app13031256/s1)). Three demonstration videos are provided. Video S1 presents the drone hardware and validates the cable detection and identification algorithm. Video S2 validates the formation flying during a powerline inspection. Video S3 demonstrates the operational aspects of the UAS including the integration of the drone with cloud services.  
Conceptualization: R.H.J. and E.E.; methodology: R.H.J.; software, validation, and investigations: L.M., L.S., N.M., N.A., K.H., S.H. and F.F.N.; writing--original draft preparation: all authors; writing--review and editing: all authors; supervision: [PERSON] and E.E.; project administration and funding acquisition, E.E. All authors have read and agreed to the published version of the manuscript.  
This project has received funding from the European Union's Horizon 2020 research and innovation program under Grant No. 861111.  
Not applicable.  
The authors would like to express gratitude to [PERSON] and [PERSON] at Deep Blue for the visual graphics design of Figure 1. We would thank [PERSON] and [PERSON] from Eucentre Foundation for sharing the 3D point cloud data for Figure 9.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.