Michael Kleiber

User-centered design and evaluation of an integrated AR-VR system for tele-maintenance

In case of undocumented machine failures on-site maintenance personnel can cooperate with a remote expert using telecommunication equipment. We present a new concept for a maintenance system which provides a synchronous shared visual workspace even when only limited bandwidth is available. A mechanic uses an Augmented Reality (AR) system which is connected to the Virtual Reality (VR) system of a remote expert. The expert interactively creates 3D instructions on his VR system that are displayed on a hand-held tablet computer of the mechanic. The mechanic considers these instructions during his maintenance work but can also interact with the live AR view to create spatial references for the expert. The system was evaluated by 18 experienced automobile mechanics. The maintenance task consisted of the disassembly of the camshaft housing of an internal combustion engine. The results show that participants completed more tasks and used less verbal instructions when using the VR system compared to a video system.

The influence of the modality of telecooperation on performance and workload

Current industrial processes often involve the collaboration of people at distant and remote locations. The technological media for such a tele-cooperation reach from simple email or text-based chatting systems to highly-sophisticated systems for an interactive video-conferencing. But with limited bandwidth the communication between persons at distant locations is often restricted to single modalities. Although this may still be suitable for some tasks, it may result into serious shortcomings and decreased performance with complex tasks like cooperative assembly or maintenance. This is because restricted communication reduces the availability of a common ground, i.e. sharing a common understanding of knowledge, opinions, and goals. The study presented in this paper examines the effect of different communication media on performance of a collaborative assembly task. The results show that tele-cooperation leads to additional verbal communication (AM(direct)=71.1s; AM(video)=145.6s; AM(audio)=204.7s) and, thus, longer times to complete the task (AM (direct)=45.95 min; AM (video)= 50.2 min; am AM(audio)=56.16 min). The percentage of relative speech duration also increases significantly. Workload measurement with NASA-TLX did not show any significant differences between cooperation modes. The results allow estimating the effect of reduced communication modalities on time to complete an assembly task. This facilitates a quantification of temporal requirements in time-critical maintenance and repair tasks.

Distortion of depth perception in virtual environments using stereoscopic displays: quantitative assessment and corrective measures

The aim of the presented research was to quantify the distortion of depth perception when using stereoscopic displays. The visualization parameters of the used virtual reality system such as perspective, haploscopic separation and width of stereoscopic separation were varied. The experiment was designed to measure distortion in depth perception according to allocentric frames of reference. The results of the experiments indicate that some of the parameters have an antithetic effect which allows to compensate the distortion of depth perception for a range of depths. In contrast to earlier research which reported underestimation of depth perception we found that depth was overestimated when using true projection parameters according to the position of the eyes of the user and display geometry.

Case study: using a stereoscopic display for mission planning

This paper reports on the results of a study investigating the benefits of using an autostereoscopic display in the training targeting process of the Germain Air Force. The study examined how stereoscopic 3D visualizations can help to improve flight path planning and the preparation of a mission in general. An autostereoscopic display was used because it allows the operator to perceive the stereoscopic images without shutter glasses which facilitates the integration into a workplace with conventional 2D monitors and arbitrary lighting conditions.

Stereoscopic desktop VR system for telemaintenance

Tele-cooperation for maintenance is usually supported by synchronous audio but only asynchronous video exchange when only limited bandwidth is available. We present an alternative approach for such a collaborative maintenance task. By utilizing techniques and technologies from Augmented Reality (AR) applications our approach can provide a synchronous shared visual context for the collaborators without a direct video link but through a Desktop VR system. To increase the spatial presence of the remote expert we employ stereoscopic displays. The effectiveness of a stereoscopic 3D system for orientation and localization was evaluated in an abstract experiment. In a more practical experiment the stereoscopic VR system was also evaluated by automobile mechanics. The benefits of stereoscopic Desktop VR systems were shown in both experiments.

Virtual Tele-Cooperation: Applying AR and VR for Cooperative Tele-Maintenance and Advanced Distance Learning

Operating complex technical systems usually requires support and maintenance. Consequently, technical personnel have to be capable and well trained. Applying just basic technical knowledge, however, is not sufficient. This is especially true for complex industrial systems with multiple interdependencies between components. Today, technicians are trained and qualified by means of courses to acquire this special knowledge. These courses take place either at the operation site requiring an expert instructor to travel or at the system manufacturer requiring the personnel to travel. Both approaches are time and, thus, cost intensive. Nowadays training can take place virtually at a distance. By applying Augmented and Virtual Reality (AR/VR) it is possible to create a feeling of presence allowing realistic communication and cooperation during the course. Our approach supports a pseudo-realistic cooperation similar to cooperation in real space. The focus is on a stepwise, user-centered approach including human factors experimentation. We describe the implementation of this experimental setup.

Fallbeispiele für VR/AR

Dieses Kapitel enthalt eine Sammlung von ausgewahlten erfolgreichen Fallbeispielen fur VR/AR aus Forschung und Praxis.

Age dependent differences in the usage of a desktop VR system for air force mission planning and preparation

This paper presents results on age dependent differences in the usage of a desktop VR system for mission planning and mission preparation in the German air force. The study investigated two tasks: one mission preparation task that demands more fluid cognitive resources like short term memory and pattern recognition; and one mission planning task in which experience was more important to complete the task. In both tasks the usage of a desktop VR system was compared to the usage of traditional media like paper maps and aerial images. In both tasks no significant interaction of age with the used media was found. However, in the mission planning task there was a weak trend that a group of senior pilots used the VR system more intensely than a group of younger pilots. In the mission preparation task pilots had to memorize and recognize objects within a target area. Response latency in identifying memorized objects of the senior pilots was significantly higher than for the two groups of younger pilots. Furthermore, there was a significant interaction of the factor age with the query condition within the tested scenes. The response latency of senior pilots was significantly higher when a false target had been shown in the test condition, rather than the correct target. In contrast the response latency of young pilots was equal for both query conditions.

Modeling the cognitive representation of basic three-dimensional spatial relations in visual short-term memory

For the prospective design of human-machine interfaces in an engineering design process, basic principles and parameters of human cognitive performance need to be known. This paper describes the results of a study that assesses parameters for the accuracy of the mental representation of basic three-dimensional spatial relations in visual short-term memory. In a laboratory experiment, 13 subjects reproduced from memory the position of a sphere relative to a second landmark. The stimuli were presented on a stereoscopic display. The mental representation of spatial relations is noisy and therefore is determined by probability density functions. The experimental results are compared with Monte Carlo simulations of stochastic models of the mental representation using hypothesized probability density functions that represent different noise models. The reported values for the parameters have important implications for the design of stereoscopic three-dimensional visualizations in human- computer interaction.

Model based evaluation of human perception of stereoscopically visualized semi-transparent surfaces

Depicting three dimensional surfaces in such a way that distances between these surfaces can be estimated quickly and accurately is a challenging task. A promising approach is the use of semi-transparent textures i.e. only some parts of the surface are colored. We conducted an experiment to determine the performance of subjects in perceiving distances between an opaque ground surface and specific points on an overlayed surface which was visualized using isolines and curvature oriented strokes. The results show that response times for curvature oriented strokes were faster compared to isolines. For a trusted interpretation of these results, a plausible explanation has to be given. We hypothesize that users visually integrate the available three dimensional positions and thereby come to an estimate. Further experiments were carried out in order to formulate a model which describes the involved perceptual process as several attention shifts between three dimensional positions. The results of the experiments are reported here.