Control System Architecture for Automatic Recovery of Fixed-Wing Unmanned Aerial Vehicles in a Moving Arrest System

Automatic recovery is an important step in enabling fully autonomous missions using fixed-wing unmanned aerial vehicles (UAVs) operating from ships or other moving platforms. However, automatic recovery in moving arrest systems is only briefly studied in the research literature, and is not yet an option when using low-cost, commercial off-the-shelf (COTS) autopilots. Acknowledging the reliability and low cost of COTS avionics, this paper adds recovery functionality as a modular extension based on non-intrusive additions to an autopilot with very general assumptions on its interface. This is achieved by line-of-sight guidance, which sends an augmented desired position to the autopilot, to ensure line-following along a virtual runway that guides the UAV into the arrest system. The translation and rotation of this line is determined by the pose of the arrest system, determined using two Global Navigation Satellite System (GNSS) receivers, where one is configured as a Real-Time Kinematic (RTK) base station. The relative position of the UAV and arrest system is also precisely estimated using RTK GNSS. Through extensive field testing, on two different fixed-wing UAVs, the system has shown its performance and reliability; 43 recovery attempts in a stationary net hit 0.01 ± 0.25m to the right and 0.07 ± 0.20m below the target in calm conditions. Further, 15 recoveries in a barge-mounted, ship-towed net hit 0.06 ± 0.53m to the right and 0.98 ± 0.27m below the target in winds up to 4 m/s. The remaining error is largely systematic, caused by communication delays, and could be reduced with more integral effect or through direct compensation.

KRRecover: An Auto-Recovery Tool for Hijacked Devices and Encrypted Files by Ransomwares on Android

Ransomwares on Android have become a challenging threat, performing tasks such as hijacking screen resources, locking devices, and encrypting files. Even worse, with the evolution of ransomwares, many ransomwares can disable USB interfaces of mobile devices. It is difficult for users to recover their devices or decrypt files with the help of other equipment and gives monetary damages to victims. In this paper, we analyse the symmetry between the ransom behaviours and the source code of screen resource hijacked ransomwares, devices locked ransomwares and files encrypted ransomwares. We also propose strategies of recovering hijacked resources, recovering hijacked devices and decrypting encrypted files. To protect mobile devices and private files from ransomwares, we design and implement an automatic recovery application—KRRecover—which is used to recover the hijacked devices and decrypt encrypted files on Android.