Underwater unmanned system refers to underwater unmanned control systems with certain autonomous capacity and autonomy, which is a combination of artificial intelligence and real-time control decision systems. Underwater unmanned systems integrate multi-discipline advanced technologies such as power, mobile, control, sensors, and artificial intelligence. It is a typical product of mechanized information intelligence and high integration and military and civilian technology. It has been successfully applied to submarine pipeline layouts and exploration, marine mineral resources exploration, marine biological resources survey, submarine reconnaissance, submarine training and other fields.

In recent years, the development of sensor technology, control theory, artificial intelligence, and signal processing algorithms has promoted the continuous improvement of underwater unmanned system navigation technology, and there have been a variety of novel underwater navigation methods. Underwater unmanned system navigation technology can be divided into the following categories: firstly, inertial navigation systems based on INS and supplemented by other navigation. INS and DVL combination navigation are important autonomous navigation methods for underwater unmanned systems. Secondly, passive navigation: geophysical navigation has the characteristics of good concealment and no need to surface for calibration. It is a research focus for underwater unmanned systems. Thirdly, beacon navigation: this navigation method applies the sonobuoy underwater positioning navigation system based on GPS to the underwater robot, which can make up for the shortcomings such as the inability to move the array position in the long baseline and the lack of surface and underwater communication ability. Underwater unmanned systems are multi-disciplinary integrated systems. To solve core problems such as autonomy, interoperability, data link, and multi-platform collaboration, the following common key technologies need to be studied. Autonomous navigation techniques are needed to ensure that the AUV can complete various tasks in the complex marine environment autonomously and collaboratively. It is necessary to solve technical problems such as environmental adaptation, autonomous docking and recovery, cooperative control of formation, cooperative navigation, and positioning, etc. Furthermore, in order to achieve data sharing between multi-platform underwater unmanned systems, we must solve technical problems such as underwater remote high-speed communication, and underwater network and air network interconnection.

This Special Issue aims to collate original research and review articles relating to advanced control, navigation, and signal processing methods for multiple autonomous unmanned systems.

Potential topics include but are not limited to the following:

• New investigation methods and sensors for path planning
• Compensation and calibration algorithms for navigation sensors
• Advanced sensors and information fusion for underwater navigation
• Underwater image enhancement and 3D image reconstruction
• Mobile robot navigation and control based on intelligent learning/bionics
• Cooperative control and navigation in multi-unmanned systems
• Quantum device and intelligent measurement
• Bionic navigation sensors
• New-concept navigation: brain-like navigation, signals of opportunity navigation
• Underwater data link communication technology