Browsing by Subject "Manipulators"
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Item The effect of unit task granularity on performance in teleoperations(Texas Tech University, 1997-08) Onal, EmrahThe choice of the command language in teleoperations has been left to systems designers, often resulting in arbitrary decisions. The granularity of the conmiand language (unit task granularity) is one of the factors that determines the level of interaction in teleoperations. A 3-D computer simulation was used to test the effect of two levels of unit task granularity (high and low) on performance in nuclear material handling. Data on humanmachine performance, operator situation awareness, and operator workload were collected and studied. Results revealed that the operator workload and level 2 situation awareness was higher in high unit task granularity than in low unit task granularity. The analysis of the data under normal mode of operation revealed that the human-machine performance (as measured in terms of time and number of errors) was higher in low unit task granularity than in high unit task granularity. During system failure, human-machine performance was higher in high unit task granularity than in low unit task granularity. This study revealed the trade-off between the performance under normal mode of operation and during system failure that is determined by the unit task granularity.Item The effects of display format and visual enhancement cues on performance of three-dimensional teleoperational tasks(Texas Tech University, 1998-05) Park, Sung HaDepth perception (as a third dimension) on a two-dimensional surface of a display interface very much determines the quality of the teleoperation system. In this research, among various teleoperation sensing requirements, the television depth requirement was investigated in detail. This research was intended to extend our understanding of the effects of visual display formats and visual enhancement cues on the ability of human operators to effectively control robot manipulators in three-dimensions. Visual display formats and visual enhancement cues were evaluated by employing a pick-and-place (picking up a virtual object and placing it into a storage rack) task in a simulated teleorobotic task environment. Three different display formats, a multiple 2-dimensional (2-D) display, a 3-dimensional (3-D) perspective display, and a 3-D stereoscopic display were simulated using a combination of various programming tools (external motif, C language, and TELEGRIP software) on a SiliconGraphics Indigo2 workstation. In order to aid human operators in perceiving depth, four different visual enhancement depth cues (including no enhancement cue) were also proposed and incorporated into each display format. Task difficulties were generated by manipulating the size of the storage rack. To compare different display formats and visual enhancement cues, various teleoperation performance measures were collected under each display condition. The measures included the time-to-completion, accuracy, subjective ratings of workload, and distance (move by the end effector). The results showed that the multiple 2-D display was superior to the perspective and stereoscopic displays, if no visual enhancement cues were provided. If provided with two of the proposed visual enhancement cues, the translucent reference cylinder and four reference lines, the stereoscopic and perspective displays were equivalent to the multiple 2-D display. The traditional single reference line was not sufficient to provide appropriate depth information on the stereoscopic and perspective displays. The stereoscopic display resulted in better performance than the perspective display only under the high task difficulty condition.