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18 June 1997 Enhanced spatial-state feedback for night-vision goggle displays
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A preliminary study was conducted to investigate the use of visual flow cues as an aid to ground and vertical drift awareness during helicopter flight and targeting while using night vision goggles (NVGs). Three displays wee compared: (1) NVG display: simulated NVG image of cockpit and external environment. (2) Overlay display: NVG image with an overlay display but with symbology flow cue field and a surrounding wire-frame globe; (3) Cut-out display: same as the overlay display but with symbology removed from the central region. Three levels of contrast were also compared using each display type. The visual scenery was displayed to subjects using a helmet-mounted virtual reality device that had a 40 by 50 degree field-of-view liquid crystal display. The study involved six pilots. Three tasks were given: (1) Search task: designate enemy targets with a helmet-mounted sight; (2) Hover task: null out all transnational and yaw rates while in a hover; (3) Search/Hover task: perform both Search and Hover tasks simultaneously. These tasks were conducted in a fixed-based helicopter simulator which used the dynamics of a small-scale model helicopter. The following performance measures were collected: (1) Pilot ability to detect and recognize targets; (2) Pilots ability to null transnational and yaw rates; (3) Time scanning the instrument panel. Subjects also rated displays for efficacy in completing the three tasks. Target detection scores conducted during the Search and Search/Hover tasks were highest using the NVG display, followed by the cut-out display. Root-mean-square (RMS) drift rate error was comparable for all display types in the Hover and Hover/Search tasks, however RMS control input activity in all the translational axes was significantly higher in both rate-cueing displays than with the NVG display. From the control input and drift rate time histories it appears that the motion cues were more compelling in the overlay and cut- out displays than those perceived in the NVG display. A significant decrease in instrument-scanning time was observed for both the overlay and cut-out displays compared to the NVG display, with pilots flying essentially head-out- of-cockpit while using the rate-cueing displays. Contrast was not observed to have a significant effect on hover performance in any of the displays.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Edward N. Bachelder and R. John Hansman Jr. "Enhanced spatial-state feedback for night-vision goggle displays", Proc. SPIE 3058, Head-Mounted Displays II, (18 June 1997);

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