In the past decade, unmanned autonomous systems have seen successful developments and a wide range of applications, from unmanned vehicles, unmanned aerial vehicles, or service robots, to space robots, marine robots and unmanned/intelligent plants, working in extreme environments (i.e. situations that are dangerous, radioactive, or of high pressure and temperature) such as in deep sea environments, nuclear power plants, or in outer space. The growing number of applications of unmanned autonomous systems in complex engineering environments, along with the increasing requirements and demands for system stability, safety, and reliability, are posing new theoretical and technological challenges in the field.

One major challenge is the provision of innovative solutions to deal with a complex operation environment. An unknown environment model, high spatiotemporal complexity, rapid changes of light intensity, and unknown disturbances arising from the dynamic environments often lead to the rapidly increasing complexity of the control algorithm, which then results in difficulties for the real-time controllers of unmanned autonomous systems. In addition, with the advent of sensing technology, providing the real-time environment information for unmanned autonomous systems through sensing the complex environment is another challenge. Therefore, revealing the properties and behaviours of unmanned autonomous systems working in complex environments could provide not only novel control algorithms, designs, and innovative control structures but could also provide solutions for systems operating realistically and efficiently in complex and unmodelled scenarios.

This Special Issue will present advances in control theories and their potential engineering applications for unmanned autonomous systems in complex environments and provide a comprehensive overview of future solutions from various computational and engineering aspects. Authors are invited to present mathematical theories, algorithms, frameworks, experiments, and applications aiming at bringing about advance control techniques for unmanned autonomous systems working within complex and unpredictable behaviours such as structural uncertainties, unknown nonlinearities, time-vary delays, unknown external disturbances, unpredictable human motions, and uncertain system dynamics. We welcome both original research and review articles.

Potential topics include but are not limited to the following:

• Control of unmanned autonomous systems
• Robot manipulator control in complex environments
• Real-time computer vision for unmanned autonomous systems
• Computational architecture for unmanned autonomous systems
• Hierarchical control of unmanned autonomous systems
• Underwater vehicle control in complex environments
• Unmanned aerial vehicle control in complex environments
• Fault-tolerant control in complex environments
• Robot sensing and exploring technologies in complex environment
• Disturbance-observer based control in complex environments
• Optimisation for systems in complex environment