Engineering topics

Bennett, C. Thomas

Publications and source records attributed to Bennett, C. Thomas.

7 records

NASA NTRS1991

Perceptual and performance consequences of flight in virtual worlds

There are two primary purposes for head-mounted systems in aeronautical settings. One is for helmet-mounted sights and teleoperated (head-slaved) weapons systems. Bennett, Johnson, Perrone, and Phatak (1988) evaluated head tracking performance during passive and controlled flight. In that study, comparisons were also made of head tracking performance in sterile and relatively complex virtual worlds. That study confirmed the robustness of head tracking performance across a wide variety of visual scenes. A second use of virtual world displays is for aircraft control. Aircraft controllability using head-mounted, panel-mounted, or simulated out-the-window scenes has been systematically examined. Those studies reported the range of rotorcraft flight tasks in which head-mounted virtual worlds provided some advantages. Two studies will be reported that examine the perceptual/performance effects of virtual worlds. The first examines head tracking performance with roll-stabilized versus non-roll stabilized virtual worlds. The purpose of the study was to (1) examine display strategies used in current display systems and (2) study the adaptability of observers to estimated glide slope angles using head-slaved versus head-stabilized imagery. The purpose of this study was to examine the usefulness of wide field-of-regards during final approaches to a runway.

Bennett, C. Thomas↗

NASA NTRS1991

The display of spatial information and visually guided behavior

The basic informational elements of spatial orientation are attitude and position within a coordinate system. The problem that faces aeronautical designers is that a pilot must deal with several coordinate systems, sometimes simultaneously. The display must depict unambiguously not only position and attitude, but also designate the relevant coordinate system. If this is not done accurately, spatial disorientation can occur. The different coordinate systems used in aeronautical tasks and the problems that occur in the display of spatial information are explained.

Bennett, C. Thomas↗

NASA NTRS1989

Synthetic perspective optical flow: Influence on pilot control tasks

One approach used to better understand the impact of visual flow on control tasks has been to use synthetic perspective flow patterns. Such patterns are the result of apparent motion across a grid or random dot display. Unfortunately, the optical flow so generated is based on a subset of the flow information that exists in the real world. The danger is that the resulting optical motions may not generate the visual flow patterns useful for actual flight control. Researchers conducted a series of studies directed at understanding the characteristics of synthetic perspective flow that support various pilot tasks. In the first of these, they examined the control of altitude over various perspective grid textures (Johnson et al., 1987). Another set of studies was directed at studying the head tracking of targets moving in a 3-D coordinate system. These studies, parametric in nature, utilized both impoverished and complex virtual worlds represented by simple perspective grids at one extreme, and computer-generated terrain at the other. These studies are part of an applied visual research program directed at understanding the design principles required for the development of instruments displaying spatial orientation information. The experiments also highlight the need for modeling the impact of spatial displays on pilot control tasks.

Bennett, C. Thomas↗

NASA NTRS1989

Heading control and the effects of display characteristics

The present study evaluates whether type of display (dot or wire frame) and direction of movement have an effect on a person's ability to actively maintain a specific heading angle. The questions addressed were: (1) does the magnitude of the heading angle errors differ in the two displays, (2) are some heading angles more difficult to maintain than others, and (3) does the magnitude of some errors differ as a function of display type and direction of movement. Differences between the results of this study and previous research are explained by methodological differences across the studies. Another factor that may be responsible for the difference between previous findings and those presented here is the type of graphics used to display the simulated motion. The physical characteristics of the display or the graphics engines that generate the scene have varied greatly across the studies. Analyses and diagrams are presented showing results of the study and the differences generated from previous studies on this subject.

Hinz, Stephanie J.↗

NASA NTRS1989

Head-mounted displays and the measurement of performance in a virtual world

The problems associated with assessing visual performance during translation and rotation in a virtual world are presented. Two studies are summarized that highlight the difficulties in defining and measuring the optical and visual variables that pilots use during the control of a craft in simulated flight. The analysis suggests that gaze line-of-sight (LOS), based on craft orientation, should be used to describe the visual information available to an observer. Head-mounted displays that utilize a headtracker provide a technology that can be used for determining an observer's LOS and generating a virtual world display. Such head-mounted displays put observers in a graphical world that exists no matter where they look.

Bennett, C. Thomas↗

NASA NTRS1989

Visually guided control of self motion

A workshop entitled 'Visually Guided Control of Movement' was held at NASA Ames Research Center on June 26 - July 14, 1989. The workshop brought together individuals with diverse backgrounds related to the areas of the visual perception and control of motion. During the workshop, participants designed and conducted experiments using NASA Ames flight simulation research facilities. These studies contrasted participants' alternative theoretical approaches to the visual control of self motion. Panel members, drawn from the workshop's participants, will discuss their approaches to the study of the control of self motion and will present interpretations of the outcomes of the workshop.

Hettinger, Lawrence J.↗

NASA NTRS1987

The visual control of simulated altitude

The ability of a subject flying an experimental flight to use the different sources of visual information by looking at the vertical tracking error was investigated using a 3 (altitude) x 3 (texture) x 2 (replication) factorial design. Each subject flew these 18 flights in the same partially counterbalanced order, constructed such that there was one flight at each of the three altitudes, and over each of the three surface textures within each successive set of three flights. The three ground-surface textures used consisted of meridian, latitudinal, and square textures described by Wolpert et al. (1983). The results showed that, in displays where only splay information was available, the subjects tended to confuse lateral motion with vertical.

Johnson, Walter W.↗