liu.seSearch for publications in DiVA
1 - 2 of 2
rss atomLink to result list
Permanent link
  • Presentation: 2016-10-12 10:15 Designrummet, A-huset, Linköping
    Blissing, Björn
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering. Statens väg- och transportforskningsinstitut, Körsimulering och visualisering (SIM).
    Blissing, Björn
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering. Statens väg- och transportforskningsinstitut, Körsimulering och visualisering (SIM).
    Driving in Virtual Reality: Investigations in Effects of Latency and Level of Virtuality2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    When developing new active safety systems or improving existing systems, conducting performance evaluations is necessary. By performing these evaluations during early development stages, potential problems can be identified and mitigated before the system moves into the production phase.

    Testing active safety systems can be difficult since the characteristic scenarios may have complex interactions. Using real vehicles for performing these types of scenarios is difficult, expensive, and potentially dangerous. Alternative methods, such as using inflatable targets, scale models, computer simulations or driving simulators, also suffer from drawbacks. Consequently, using virtual reality as an alternative to the traditional methods has been proposed. In this case, a real vehicle is driven while wearing a head-mounted display that presents the scenario to the driver.

    This research aims to investigate the potential of such technology. Specifically, this work investigates how the chosen technology affects the driver. This investigation has been conducted through a literature review. A test platform was constructed, and two user studies using normal drivers were performed. The first study focused on the effects of visual time delays on driver behavior. This study revealed that lateral behavior changes with added time delays, whereas longitudinal behavior appears unaffected. The second study investigated how driver behavior is affected by different modes of virtuality. This study demonstrated that drivers perceived mixed reality as more difficult than virtual reality.

    The main contribution of this work is the detailed understanding of how time delays and different modes of virtuality affect drivers. This is important knowledge for selecting which scenarios are suitable for evaluation using virtual reality.

    List of papers
    1. Augmented and Mixed Reality as a tool for evaluation of Vehicle Active Safety Systems
    Open this publication in new window or tab >>Augmented and Mixed Reality as a tool for evaluation of Vehicle Active Safety Systems
    2013 (English)In: Proceedings of the 4th International Conference on Road Safety and Simulation, Rome, Italy, 23-25 October, 2013, Aracne editrice, 2013Conference paper (Other academic)
    Abstract [en]

    Even though the realism of driving simulators increases constantly, there is a potential issue with how representative the test is compared to a real life scenario. An alternative to simulators is to present a mixture of real and simulated environment to the driver and perform the scenario at a test track when driving a real vehicle. This enables an efficient way of testing that inherits many of the advantages of driving simulators as well as some of the advantages of physical testing in prototype vehicles. The present paper is a compilation of previous research in augmented reality in vehicle driving situations, focusing on technical limitations of Head-Mounted-Displays.

    Place, publisher, year, edition, pages
    Aracne editrice, 2013
    Keyword
    Simulation, Driving (veh), Visual display, Test method
    National Category
    Interaction Technologies
    Research subject
    90 Road: Vehicles and vehicle technology, 91 Road: Vehicle design and construction
    Identifiers
    urn:nbn:se:liu:diva-131619 (URN)978-8854864153 (ISBN)
    Conference
    RSS2013 Road Safety and Simulation - International Conference. October 23-25, 2013. Rome, Italy
    Available from: 2016-09-28 Created: 2016-09-28 Last updated: 2016-09-28Bibliographically approved
    2. A Technical Platform using Augmented Reality for Active Safety Testing
    Open this publication in new window or tab >>A Technical Platform using Augmented Reality for Active Safety Testing
    2015 (English)In: 2015 Road Safety & Simulation International Conference Proceedings / [ed] Dr. Essam Radwan, Dr. Mohamed Abdel-Aty, Orlando, USA: University of Central Florida , 2015, 793-803 p.Conference paper (Refereed)
    Abstract [en]

    This paper describes the design of a video see-through augmented reality system for active safety testing. The development is explained in detail, with focus on the design considerations for the different subsystems. It is shown that it is possible to build a system using available commercial off-the-shelf components, while still maintaining the performance needed for the intended application. Accuracy and resolution requirements of the tracking systems are discussed along with measurement methods. We also examine how to use the hardware efficiently to minimize latency and a device to measure and quantify end-to-end latency has been developed.

    Place, publisher, year, edition, pages
    Orlando, USA: University of Central Florida, 2015
    Keyword
    Active safety system, Test, Simulation, Design (overall design), Characteristics
    National Category
    Interaction Technologies
    Research subject
    90 Road: Vehicles and vehicle technology, 911 Road: Components of the vehicle
    Identifiers
    urn:nbn:se:liu:diva-131620 (URN)9781495174452 (ISBN)
    Conference
    2015 Road Safety & Simulation International Conference
    Funder
    VINNOVA, 2011-01819]
    Available from: 2016-09-28 Created: 2016-09-28 Last updated: 2016-09-28Bibliographically approved
    3. Effects of Visual Latency on Vehicle Driving Behavior
    Open this publication in new window or tab >>Effects of Visual Latency on Vehicle Driving Behavior
    2016 (English)In: ACM Transactions on Applied Perception, ISSN 1544-3558, E-ISSN 1544-3965, Vol. 14, no 1, 5:1-5:12 p., 5Article in journal (Refereed) Published
    Abstract [en]

    Using mixed reality in vehicles provides a potential alternative to using driving simulators when studying driver-vehicle inter- action. However, virtual reality systems introduce latency in the visual system that may alter driving behavior, which, in turn, results in questionable validity. Previous studies have mainly focused on visual latency as a separate phenomenon. In this work, latency is studied from a task-dependent viewpoint to investigate how participants’ driving behavior changed with increased latency. In this study, the investigation was performed through experiments in which regular drivers were subjected to different levels of visual latency while performing a simple slalom driving task. The drivers’ performances were recorded and evaluated in both lateral and longitudinal directions along with self-assessment questionnaires regarding task performance and difficulty. All participants managed to complete the driving tasks successfully, even under high latency conditions, but were clearly affected by the increased visual latency. The results suggest that drivers compensate for longer latencies by steering more and increasing the safety margins but without reducing their speed.

    Place, publisher, year, edition, pages
    New York, NY, USA: Association for Computing Machinery (ACM), 2016
    Keyword
    Driving, Vision, Delay, Variability, Simulator (driving), Performance (road user)
    National Category
    Interaction Technologies
    Research subject
    80 Road: Traffic safety and accidents, 841 Road: Road user behaviour
    Identifiers
    urn:nbn:se:liu:diva-131621 (URN)10.1145/2971320 (DOI)
    Projects
    Next Generation Test Methods for Active Safety Functions
    Funder
    VINNOVA, 2011-01819]
    Available from: 2016-08-26 Created: 2016-09-28 Last updated: 2016-09-28Bibliographically approved
    4. Driver behavior in mixed and virtual reality: a comparative study
    Open this publication in new window or tab >>Driver behavior in mixed and virtual reality: a comparative study
    2016 (English)In: Proceedings of the DSC 2016 Europe / [ed] Andras Kemeny, Frédéric Mérienne, Florent Columbet, Stéphane Espié, Paris, France: Driving Simulation Association , 2016, 179-186 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents a comparative study of driving behavior when using different virtual reality modes. Test subjects were exposed to mixed, virtual, and real reality using a head mounted display capable of video see-through, while performing a simple driving task. The driving behavior was quantified in steering and acceleration/deceleration activities, divided into local and global components. There was a distinct effect of wearing a head mounted display, which affected all measured variables. Results show that average speed was the most significant difference between mixed and virtual reality, while the steering behavior was consistent between modes. All subjects but one were able to successfully complete the driving task, suggesting that virtual driving could be a potential complement to driving simulators.

    Place, publisher, year, edition, pages
    Paris, France: Driving Simulation Association, 2016
    National Category
    Interaction Technologies
    Identifiers
    urn:nbn:se:liu:diva-131622 (URN)
    Conference
    Driving Simulator Conference, 7-9 sept, 2016. Paris, France
    Projects
    Next Generation Test Methods for Active Safety Functions
    Funder
    VINNOVA, 2011-01819]TrenOp, Transport Research Environment with Novel Perspectives
    Available from: 2016-09-19 Created: 2016-09-28 Last updated: 2016-09-28Bibliographically approved
  • Presentation: 2016-11-04 13:15 Alan Turing, Hus E, Linköping
    Krishnamoorthi, Vengatanathan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Krishnamoorthi, Vengatanathan
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Efficient and Adaptive Content Delivery of Linear and Interactive Branched Videos2016Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Video streaming over the Internet has gained tremendous popularity over recent years and currently constitutes the majority of Internet traffic. The on-demand delivery of high quality video streaming has been enabled by a combination of consistent improvements in residential download speeds, HTTP-based Adaptive Streaming (HAS), extensive content caching, and the use of Content Distribution Networks (CDNs). However, as large-scale on-demand streaming is gaining popularity, several important questions and challenges remain unanswered, including determining how the infrastructure can best be leveraged to provide users with the best possible playback experience. In addition, it is important to develop new techniques and protocols that facilitate the next generation of streaming applications. Innovative services such as interactive branched streaming are gaining popularity and are expected to be the next big thing in on-demand entertainment.

    The major contributions of this thesis are in the area of efficient content delivery of video streams using HAS. To address the two challenges above, the work utilizes a combination of different methods and tools, ranging from real-world measurements, characterization of system performance, proof-of-concept implementations, protocol optimization, and evaluation under realistic environments. First, through careful experiments, we evaluate the performance impact and interaction of HAS clients with proxy caches. Having studied the typical interactions between HAS clients and caches, we then design and evaluate content-aware policies to be used by the proxy caches, which parse the client requests and prefetch the chunks that are most likely to be requested next. In addition, we also design cooperative policies in which clients and proxies share information about the playback session. Our evaluations reveal that, in general, the bottleneck location and network conditions play central roles in which policy choices are most advantageous, and the location of the bottlenecks significantly impact the relative performance differences between policy classes. We also show that careful design and policy selection is important when trying to enhance HAS performance using proxy assistance.

    Second, this thesis proposes, models, designs, and evaluates novel streaming applications such as interactive branched videos. In such videos, users can influence the content that is being shown to them. We design and evaluate careful prefetching policies that provides seamless playback even when the users defer their path choices to the last possible moment. We derive optimized prefetching policies using an optimization framework, design and implement effective buffer management techniques for seamless playback at branch points, and use parallel TCP connections to achieve efficient buffer workahead. Through performance evaluations, we show that our policies can effectively prefetch data of carefully adapted qualities along multiple alternative paths so to ensure seamless playback, offering users a pleasant viewing experience without playback interruptions.