Recently, various highly complex unmanned aerial systems, such as satellites, spacecrafts, unmanned aerial vehicles, or unmanned aerial manipulators, have been developed to improve the execution efficiency of various tasks, including forest fire monitoring and fighting, powerline/pipeline inspection, surveillance and monitoring, aerial manipulation, and smart city observation.

Increases in complexity render these unmanned aerial systems (UASs) susceptible to faults, which may significantly degrade the control performance or even cause catastrophic accidents. Moreover, compared with single UASs, the cooperation of networked UASs can significantly increase the task execution efficiency. However, the increased number of actuators, sensors, and components may make the networked UASs more susceptible to faults. To attenuate the adverse effects caused by these faults, fault-tolerant control (FTC) and fault-tolerant cooperative control (FTCC) strategies have been developed for single UASs and networked UASs, respectively. More recently, the study of FTC/FTCC has faced major challenges with increasing safety requirements. Many new factors now have to be considered that have not yet been addressed, therefore, there is an urgent need for the latest developments in FTC/FTCC techniques for UASs to be pursued.

The aim of this Special Issue is to bring together original research and review articles in the field of FTC/FTCC technology and promote related techniques for UASs. We hope that this Special Issue will help to solve the problems encountered in theory and practical applications for safe control of UASs.

Potential topics include but are not limited to the following:

• New FTC techniques and implementations for UASs, such as satellites, spacecraft, unmanned aerial vehicles, unmanned airships, or unmanned aerial manipulators
• Integrated designs of fault detection and diagnostics (FDD) and FTC for UASs
• FTCC designs for networked UASs against actuator and sensor faults
• Leader-following/distributed FTCC of networked UASs
• Safe control of UASs against actuator, sensor, and communication attacks
• Fault-tolerant containment control of networked UASs
• FTC/FTCC designs for UASs with various constraints
• Proportional–integral–derivative (PID)-like FTC/FTCC designs for UASs
• Intelligent fuzzy, neural, or fuzzy neural adaptive FTC/FTCC designs for UASs
• Adaptive reinforcement learning for FTC/FTCC of UASs
• Fractional-order FTC/FTCC of UASs
• Fault-tolerant guidance and control for UASs
• Robust FTC/FTCC designs and analyses for UASs in the presence of disturbances/uncertainties
• New developments in communication techniques and airspace rules for ensuring flight safety