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Perception-Based Synthetic Cueing for Night-Vision Device Rotorcraft Hover Operations
Abstract
Helicopter flight using night-vision devices (NVDs) is difficult to perform, given evidence by the high accident rate associated with NVD flight compared to day operation. A mishap analysis of NVD-related helicopter accidents was conducted which found approximately 70% of the accidents attributable to pilot misperception of the flight environment, with the most frequently misperceived states being spatial in nature and in the hover regime. While hardware changes such as increasing the field of view or image resolution may alleviate some of the problems, it is unlikely that they will address all of the perceptual issues. The approach proposed in this thesis is to augment the NVD image with synthetic cueing, whereby the cues would emulate position and motion in an ecological fashion and appear to be actually occurring in physical space on which they are overlaid. Synthetic cues allow for selective enhancement of perceptual state gains to match the task requirements. The perceptual gains examined were aircraft positional error along the three translational axes. A hover cue set was developed based on an analogue of a physical target used in a flight handling qualities tracking task, a perceptual task analysis for hover, and fundamentals of human spatial perception. The display was implemented on a simulation environment, constructed using a virtual reality device, an ultrasound head-tracker, and a fixed-base helicopter simulator. Seven highly trained helicopter pilots were used as experimental subjects and tasked to maintain hover in the presence of aircraft positional disturbances while viewing a synthesized NVD environment and the experimental hover cues. The simulation employed a number of unique techniques that enabled identification of visual perception and division-of-attention effects. Measures of hover performance and subjective ratings were collected, and frequency analysis was used to measure system (i.e., pilot/display/vehicle suite) stability and bandwidth. Significant performance improvements in NVD flight were observed when using synthetic cue augmentation. Subjective ratings showed longitudinal control to be more difficult than in the other axes for both single and multi-axis control. This thesis demonstrates that artificial magnification of perceptual states through synthetic cueing can be an effective method of improving night-vision helicopter hover operations.
... To maintain the global optical flow, as it is necessary for tau-guidance, the surrounding environment can be rebuilt with microtextures (fine details) and macrotextures (large objects) [19], [29]. The latter can be obstacles, like poles or trees, while microtextures represent the detailed fine-grained texture of the surface of objects or small and detailed parts of a macrotexture, like branches or leaves of a tree. ...
... In addition to observer-oriented cues, pictorial depth cues provide monocular cues and can be used to design 3D-conformal see-through scenery visualizations. An excerpt of pictorial depth cues from [23] and [29] are the following principles: Relative size: Smaller objects appear farther away, when compared to objects, which are physically similar in size. Relative density: The texture gradient or cluster of objects, that get finer with increasing distance (compression). ...
... Contour lines additionally give valuable feedback about the terrain surface itself, especially in the mountains or in hilly areas. Finally, in [23] and [29], it is concluded that motion parallax and occlusion are under the top three of the most effective depth cues. Hence, section 4 focuses on the principle of occlusion using see-through displays in the application of helicopter flight in DVE. ...
The increasing maturity of head-tracked optical see-through Head-Mounted Displays (HMDs) for pilot assistance in Degraded Visual Environments (DVE) enables a 3D-conformal presentation of well developed flight guidance parameters, added by scenery content for collision avoidance. With more and more information displayed on the HMD, the challenge of preventing visual clutter grows. In this paper, visual clutter will be analyzed and derived concepts for reducing clutter will be discussed. Additionally, extensions and tailored modifications of the Rotorcraft Simulation Environment (ROSIE) at the Institute of Helicopter Technology for enhanced future pilot evaluations of such HMD-DVE solutions will be described.
A compilation and an analysis of helicopter handling qualities data are presented in two volumes. This volume contains a collection of basic descriptive data, stability derivatives, and transfer functions for a six-degrees-of-freedom, quasi-static model. The data are arranged in a common, compact format for each of the five helicopters represented. The vehicles include the OH-6A, BO-105, AH-1G, UH-1H, and CH-53D.
Fidelity requirements for Army flight training simulators are explored using a manual control theory approach. The first step is to define 'simulator fidelity' in operational terms which provide a basis for each of the subsequent steps. This definition is accompanied by a taxonomy of measurable fidelity parameters. The next step, also of a preparatory nature, is the analysis of Army flight training missions.
NASA's Ames Research Center has developed head-up display formats and a flight control system that allows a Harrier V/STOL attack aircraft pilot to make 'blind' landings on a 40 × 70-ft. pad. The new technology was largely developed in simulations, but has been verified by test flights on a YAV-8B Harrier prototype. The blind landing technology is intended for a next-generation advanced short-takeoff, vertical landing (ASTOVL) aircraft.
To investigate the breadth of visual illusions experienced by aviators flying with night vision devices (NVDs), an open-ended questionnaire was distributed to the military helicopter community. Of the 242 returned questionnaires, there were 221 image intensification (I2) reports and 21 thermal imaging system reports. Most sensory events occurred at night, during low illumination, good weather, and over varied terrain. Contributing factors included inexperience, division of attention, and fatigue. Frequently reported illusions were misjudgments of drift, clearance, height above the terrain, and attitude. Also reported were illusions due to external lights and disturbed depth perception caused by differences in brightness between I2 tubes. Other respondents cited hardware problems and physiological effects. There were no obvious differences between the experiences of I2 users and FLIR (forward-looking infrared) users. Although incidence rates cannot be inferred from these data, the variety of aviator reports will be useful to all those connected with the human factors and safety of NVDs.
Experimental testing of 10 subjects wearing the AN/PVS-5A (II GEN) night vision goggles (NVG) and ANVIS (III GEN) NVG was conducted under field conditions of ambient starlight illumination (approx. 10-5 mL). The parameters measured were: 1) binocular visual acuity (BVA), 2) stereopsis (depth perception), and 3) a subjective forced choice test. Results showed that BVA was 20/124 and 20/86 for the II and III GEN NVG, respectively. This difference was statistically as well as clinically significant. The stereopsis test results were inconclusive and variable because of the limited sample size and relative inexperience of the subjects in using NVG. Neither BVA nor stereopsis with the NVG was found to be related to standard baseline measures of these parameters in the clinic. Even though the ANVIS has better gain, resolution and sensitivity, 6 out of 10 subjects preferred the AN/PVS-5A for viewing the subjective test. This seemingly paradoxical finding was surmised to be a result of the presence or lack of scene contrast due to the differential sensitivities in the II and III GEN photocathode tubes.
This manual is an updated and extensively revised successor to the 1985 edition of the Night Vision Manual for the Flight Surgeon (USAFSAM-SR-85-3) . It is a definitive reference that provides current guidance for flight surgeons who can use it as a source document in providing night vision briefings, conducting NVG training sessions, discussing aeromedical limitations, and applying appropriate medical standards. This document can also be used by the flight surgeon in conjunction with night vision demonstration kits and other teaching aids. Field of view, Night vision physiology, Optometrist, Flight surgeon, NVG preflight testing procedures, Rods and cones, Night Vision Goggles (NVG), Ophthalmologist, Unaided night vision.