Die Simulation von Prozessen ist schon immer ein zentraler Bestandteil bei der Entwicklung von Produkten. Durch sie können Aussagen über das Produkt gewonnen und Vorgänge verändert, erneuert oder auch verbessert werden. Virtual Reality spielt in diesem Zusammenhang eine immer größere Rolle.

Augmented Reality (AR) head-mounted display (HMD) provides users with an immersive virtual experience in the real world. The portability of this technology affords various information display options for construction workers that are not possible otherwise. The information delivered via an interactive user interface provides an innovative method to display complex building instructions, which is more intuitive and accessible compared with traditional paper documentations. However, there are still challenges hindering the practical usage of this technology at the construction jobsite. As a technical restriction, current AR HMD products have a limited field of view (FOV) compared to the human vision range. It leads to an uncertainty of how the obstructed view of display will affect construction workers' perception of hazards in their surrounding area. Similarly, the information displayed to workers requires rigorous testing and evaluation to make sure that it does not lead to information overload. Therefore, it is essential to comprehensively evaluate the impacts of using AR HMD from both perspectives of task performance and cognitive performance. This dissertation aims to bridge the gap in understanding the cognitive impacts of using AR HMD in construction assembly tasks. Specifically, it focuses on answering the following two questions: (1) How are task performance and cognitive skills affected by AR displays under complex working conditions? (2) How are moment-to-moment changes of mental workload captured and evaluated during construction assembly tasks? To answer these questions, this dissertation proposed two experiments. The first study tests two AR displays (conformal and tag-along) and paper instruction under complex working conditions, involving different framing scales and interference settings. Subjective responses are collected and analyzed to evaluate overall mental workload and situation awareness. The second study focuses on exploring an electroencephalogram (EEG) based approach for moment-to-moment capture and evaluation of mental workload. It uncovers the cognitive change on the time domain and provides room for further quantitative analyzing on mental workload. Especially, two frameworks of mental workload prediction are proposed by using (1) Long Short-Term Memory (LSTM) and (2) one-dimensional Convolutional Neural Network (1D CNN)-LSTM for forecasting EEG signal and, classifying task conditions and mental workload levels respectively. The approaches are tested to be effective and reliable for predicting and recognizing subjects' mental workload during assembly. In brief, this research contributes to the existing knowledge with an assessment of AR HMD use in construction assembly, including task performance evaluation and both subjective and physiological measurements for cognitive skills. / Doctor of Philosophy / Augmented Reality (AR) is an emerging technology that bridges the gap between virtual creatures and physical world with an immersive display experience. Today, head-mounted display (HMD) is well developed to meet the demands for portable AR devices. It provides interactive and intuitive display of 2D graphical information to make it easier to understand for users. Therefore, AR display has been studied in the past few years for a more simplified and productive construction assembly process. However, given the premise that construction is a high-risk industry, introducing such display technology to the jobsite needs to be carefully tested. One obstacle in current AR HMD products is the restriction of field of view (FOV), which may block users' view in presenting large-scale 3D objects. In construction assembly, workers need to deal with tasks in different scopes, such as wood framing for a residential house. Consequently, it is necessary to study how such technical challenge will impact workers' performance under different task conditions. Another concern comes from the mental perspective. Although AR display may bring convenience in acquiring effective information, it is difficult to measure if this generates excessive mental burden to users. Especially for construction workers, whether the overlaid display will cause distraction and information overload is crucial for protecting workers from hazards. To address the problems, this dissertation explores the gap in previous literature, where mental workload is not well studied for using AR HMD in construction assembly. Two experiments are conducted to comprehensively evaluate the impacts of AR displays on both assembly performance and users' mental status. The outcomes bring implications to theoretical and practical aspects. First, it compares two AR displays (2D tag-along image and 3D conformal model) with traditional paper documentation for assembly performance (efficiency and accuracy) and users' cognitive skills (mental workload and situation awareness). The findings revealed the impact of FOV restriction and provided a strategic solution to selecting display method for different task conditions. Second, it proposes a physiological approach to calculate mental workload from analyzing the features from brain waves. It uncovered the latent mental changes during the assembly. Furthermore, two deep learning approaches are applied to predict and classify mental workload. The prediction model depicted the trend of mental workload in eighteen seconds based on an eighty-four-second training set, while the classifier recognized two task conditions with different mental workload levels with an accuracy of 93.6%. The results have promising potential for future research in detecting and preventing abnormality in workers' mental status. In addition, it is generalizable to apply in other construction tasks and AR applications.

The main aim of this thesis was to evaluate the performance of the contrast sensitivity clock (CSC), a new screening device for measuring contrast sensitivity (CS) and glare. This device allows CS without glare, with glare and disability glare scores to be recorded. After initial data collection the design of the CSC was slightly amended improving the performance of the device. The amended design of the CSC was shown to be a valid, discriminative and repeatable measure for purpose. The CSC is also a quick test to perform and is relatively cheap to produce. If all these factors are considered it shows potential to become the test of choice for the assessment of visual glare. A head-mounted display system was also evaluated in terms of the glare effects it may cause. The monocular display screen of the device significantly reduced the CS of the eye directly exposed but also had an effect on binocular performance, reducing amounts of binocular summation. Electronic devices, including head-mounted displays and satellite navigation systems can seriously affect CS at low luminance levels, similar to those found when driving at night.

The main aim of this thesis was to evaluate the performance of the contrast sensitivity clock (CSC), a new screening device for measuring contrast sensitivity (CS) and glare. This device allows CS without glare, with glare and disability glare scores to be recorded. After initial data collection the design of the CSC was slightly amended improving the performance of the device. The amended design of the CSC was shown to be a valid, discriminative and repeatable measure for purpose. The CSC is also a quick test to perform and is relatively cheap to produce. If all these factors are considered it shows potential to become the test of choice for the assessment of visual glare. A head-mounted display system was also evaluated in terms of the glare effects it may cause. The monocular display screen of the device significantly reduced the CS of the eye directly exposed but also had an effect on binocular performance, reducing amounts of binocular summation. Electronic devices, including head-mounted displays and satellite navigation systems can seriously affect CS at low luminance levels, similar to those found when driving at night.

I denna artikel undersöks HoloLens 2 som verktyg för att förmedla LEGO-bygginstruktioner genom att använda Augmented Reality (AR). Traditionella instruktionsmetoder såsom text, bilder och video har börjat få konkurrens av AR-tekniken. AR har potentialen att förbättra inlärning och effektivisering av instruktions processen genom att lägga till digitalt innehåll i den fysiska verkligheten.  I artikeln diskuteras både fördelar och nackdelar med att använda sig av AR-instruktioner jämfört med traditionella medier, såsom pappersinstruktioner och framhäver AR’s potential inom områden som exempelvis utbildning, sjukvård och tillverkning. Tidigare studier har visat ökat engagemang, effektivitet och minskad ansträngning hos användare som använder sig av AR-instruktioner. Ibáñez m.fl. (2014) genomförde en undersökning där de använde sig av AR bland studenter och fick positiv feedback vad gäller användning av AR i ett lärandesammanhang.  Artikeln inriktar sig specifikt på användningen av AR Head Mounted Display (HMD), som i detta fall kommer vara en HoloLens 2 för att förmedla LEGO-bygginstruktioner. Med hjälp av HoloLens 2 får användaren en tydligare uppfattning om monteringsprocessen och visualisera de olika komponenterna i 3D. Detta blir fördelaktigt för undersökningen när det gäller att hantera små LEGO-komponenter för att placera dem på rätt plats.  Slutresultatet för undersökningen av att använda HoloLens 2 som verktyg för att förmedla LEGO-bygginstruktioner, visade sig ha både fördelar och nackdelar som kommer att diskuteras senare i artikeln.

It was analyzed if instructions on a head-worn Augmented Reality display (AR-HWD) are better for manual industrial assembly tasks than instructions on a stationary screen. A prototype was built which consisted of virtual instruction screens for two example assembly tasks. In a comparison study participants performed the tasks with instructions through an AR-HWD and alternatively through a stationary screen. Questionnaires, interviews and observation notes were used to evaluate the task performances and the user experience. The study revealed that the users were excited and enjoyed trying the technology. The perceived usefulness at the current state was diverse, but the users saw a huge potential in AR-HWDs for the future. The task accuracy with instructions on the AR-HWD was equally good as with instructions on the screen. AR-HWDs are found to be a better approach than a stationary screen, but technological limitations need to be overcome and workers need to train using the new technology to make its application efficient.

<p>When users begin to experience virtual reality (VR) for the first time, they can be met with some degree of motion sickness and nausea, especially if continuous joystick locomotion is used. The symptoms that are induced during these VR experiences fall under the umbrella term cybersickness, and due to these uncomfortable experiences, these users can get a bad first impression and abandon the innovative technology, not able to fully appreciate the convenience and fascinating adventures VR has to offer. As such, this project compares the effects of two cybersickness mitigation methods (Dynamic Field of View (FOV) and Virtual Reference Frame), both against each other and combined, on user-reported cybersickness symptoms to determine the best combination to implement in commercial applications to help create more user-friendly VR experiences. The hypothesis is that combining the FOV reduction and the resting frame methods can mitigate VR cybersickness more effectively without hindering the user’s experience and the virtual nose method is more potent at mitigating cybersickness compared to dynamic FOV. To test these hypotheses, an experimental game was developed for the Meta Quest 2 with five levels: a tutorial level and four maze levels (one for each scenario). The participants were asked to complete the tutorial level until they got used to the virtual reality controls, and then they were instructed to complete the maze level twice with one of the following conditions for each run: no method, dynamic field of view only, virtual nose only, and dynamic field of view and virtual nose combined. After completing each maze trial, the participants were asked to complete a simulator sickness questionnaire to get their thoughts on how much sickness they felt during the test. Upon concluding the testing phase with 36 participants and compiling the data, the results showed that while the subjects preferred the dynamic FOV method even though they were able to complete the trials significantly faster with the virtual nose method, it is inconclusive regarding which method is truly more effective. Furthermore, the results showed that it is also inconclusive if the scenario with both methods enabled is significantly better or worse than either method used separately.</p>