Sensor-enhanced 3D conformal cueing for safe and reliable HC operation in DVE in all flight phases

Abstract

Low level helicopter operations in Degraded Visual Environment (DVE) still are a major challenge and bear the risk of potentially fatal accidents. DVE generally encompasses all degradations to the visual perception of the pilot ranging from night conditions via rain and snowfall to fog and maybe even blinding sunlight or unstructured outside scenery. Each of these conditions reduce the pilots' ability to perceive visual cues in the outside world reducing his performance and finally increasing risk of mission failure and accidents, like for example Controlled Flight Into Terrain (CFIT). The basis for the presented solution is a fusion of processed and classified high resolution ladar data with database information having a potential to also include other sensor data like forward looking or 360° radar data. This paper reports on a pilot assistance system aiming at giving back the essential visual cues to the pilot by means of displaying 3D conformal cues and symbols in a head-tracked Helmet Mounted Display (HMD) and a combination with synthetic view on a head-down Multi-Function Display (MFD). Each flight phase and each flight envelope requires different symbology sets and different possibilities for the pilots to select specific support functions. Several functionalities have been implemented and tested in a simulator as well as in flight. The symbology ranges from obstacle warning symbology via terrain enhancements through grids or ridge lines to different waypoint symbols supporting navigation. While some adaptations can be automated it emerged as essential that symbology characteristics and completeness can be selected by the pilot to match the relevant flight envelope and outside visual conditions.

Virtual Cockpit Instruments—How Head-Worn Displays Can Enhance the Obstacle Awareness of Helicopter Pilots

“…Another notable development in this area is the SFERION ® system by Hensoldt [20]. Based on sensor and database information, the HWD shows a conformal terrain grid and contour lines to avoid controlled ight into terrain.…”

Display of real-time 3D sensor data in a DVE system

“…To avoid misinterpretations caused by human 3D perception a cueing system represents terrain as a grid combined with or independent from contour lines or ridge lines. Again the depiction of the fused terrain information derived from terrain databases and segmented 3D sensor terrain data is meant to augment the pilots outside view while trying to avoid cluttering [1] . The following figure 1 shows examples of a terrain grid with ridge lines generated from fused database and LiDAR data.…”

Capability comparison of pilot assistance systems based solely on terrain databases versus sensor DB fused data systems

“…Figure 7 illustrates the effects of beam divergence (box height) and range accuracy (box width) while measuring a terrain surface with an object located on top. The usability of the SferiSense LiDAR as a highly precise terrain surface measuring device is proven in flight [8], [9] . Figure 11 in chapter 5 shows the details that can be measured and shown as a 3D conformal terrain surface using the SferiSense LiDAR.…”

“…To safely operate the helicopter in an obstacle environment close to the terrain in addition to handling qualities the pilot has to maintain situational awareness in all the necessary flight maneuvers. The well accepted method is to augment the pilots' outside vision via head-up projected outside world conformal cues [8], [9] , so called 3D conformal cues, and potentially additional imaging sensor information. Within this paper the term conformal is understood in the sense that "conformal information is that which overlays the real world element that it is meant to portray irrespective of the viewing position" [10] .…”