Key Technologies and Applications of UAVs in Underground Space: A Review

Robots, particularly unmanned aerial vehicles (UAVs), offer significant advantages in challenging environments. Their application in searching and exploring underground areas has garnered considerable attention. However, subsurface environments present various challenges, such as a lack of localization signals, weak illumination, and severe electromagnetic interference, which make positioning, detecting, and communicating difficult for UAVs. The ability to address these challenges is crucial for successful underground UAV applications. In this article, we highlight high-performance perception and communication as key technologies for underground UAVs. We first summarize the current state of UAV perception and communication, and then analyse the supporting role of multi-source fusion perception technology and joint communication optimization methods for underground UAVs. We also evaluate existing subsurface UAV applications and discuss potential research challenges and future development directions to overcome these challenges in underground UAV application scenarios.