Enabling Aircraft Emergency Landings Using Active Visual Site Detection

Abstract

Abstract. The ability to automate forced landings in an emergency such as engine failure is an essential ability to improve the safety of Unmanned Aerial Vehicles operating in General Aviation airspace. By using active vision to detect safe landing zones below the aircraft, the reliability and safety of such systems is vastly improved by gathering up-to-the-minute information about the ground environment. This paper presents the Site Detection System, a methodology utilising a downward facing camera to analyse the ground environment in both 2D and 3D, detect safe landing sites and characterise them according to size, shape, slope and nearby obstacles. A methodology is presented showing the fusion of landing site detection from 2D imagery with a coarse Digital Elevation Map and dense 3D reconstructions using INS-aided Structure-from-Motion to improve accuracy. Results are presented from an experimental flight showing the precision/recall of landing sites in comparison to a hand-classified ground truth, and improved performance with the integration of 3D analysis from visual Structure-from-Motion.

Zoom lens calibration with zoom- and focus-related intrinsic parameters applied to bundle adjustment

“…A zoom camera system is capable of changing the focal length, focus distance, and aperture value to suit different fields of view (FOVs), depths of field (DOFs), and lighting conditions. Thus, zoom lens devices have been extensively used in various applications, e.g., robotic vision and active vision (Utsumi et al, 2012;Warren et al, 2013), augmented reality (Chendeb et al, 2013;Tatzgern et al, 2014), object detection or tracking (Kim et al, 2013;Tao et al, 2009;Tarhan and Altug, 2011), and traffic monitoring (Schmidt et al, 2009;Song and Tai, 2006). However, in the field of close-range photogrammetry, fixed lenses are more commonly used than zoom lenses mainly because of difficulties in metric modeling and calibration of zoom lens cameras (Ahmed and Farag, 2000;Wu et al, 2013).…”

Free LSD: Prior-Free Visual Landing Site Detection for Autonomous Planes

“…However, relying on a fixed height makes this approach disadvantageous in case of emergencies. The closest approach to ours is presented by Warren et al [15]. However, we see the following caveats that we address with the present work: Firstly, the terrain classification is derived from stored data.…”

The Value of Step-by-Step Risk Assessment for Unmanned Aircraft

“…Metrics for safety, including hazard metrics and risks metrics are presented in [17], in [18] a software safety case is developed, and in [19] a generic safety case is presented based on experience with NASA unmanned aircraft missions. A method for automatically finding a proper landing area for an aircraft in emergency descent is shown in [20], [21], and the ability of a fixed wing aircraft to glide to a designated emergency landing area is presented in [22]. In [23] a study for ground impact fatalities resulting from power failure and subsequent uncontrolled glide is presented.…”