Flight control techniques and classification of ducted fan aerial vehicles

Recent progress in the flight control design has inspired sophisticated autonomous aerial vehicles to accomplish various tasks. Among different vertical take-off and landing airborne vehicles, the ducted fan aerial vehicles (DFAVs) are a significantly important type of tail-sitter aircraft because their moving and actuated parts are shielded by annular fuselage called duct, which is crucial for aircraft protection as well as operator safety with the vehicle's ability to fly in confined, cluttered, and hazardous environments. Moreover, they exhibit the characteristics of both fixed-wing airplanes and helicopters. Furthermore, these vehicles inherit several other qualities such as long perch, stare capability and large payload capacity. This first review paper on DFAVs aims to overview the latest advances while focusing on several aspects related to these vehicles. First, a comprehensive history and a novel categorization are provided with available flying platforms developed worldwide, and their features with pros and cons to other airborne configurations are summarized. Next, different flight control approaches employed to control these aircraft are explained. Finally, concluding remarks, key observations, existing challenges, and new trends in the conducted survey are discussed.