=Paper= {{Paper |id=Vol-2082/paper_9 |storemode=property |title=Design Recommendations for HMD-based Assembly Training Tasks |pdfUrl=https://ceur-ws.org/Vol-2082/paper_9.pdf |volume=Vol-2082 |authors=Stefan Werrlich,Phuc-Anh Nguyen,Austino-Davis Daniel,Carlos Emilio Franco Yanez,Carolin Lorber,Gunther Notni |dblpUrl=https://dblp.org/rec/conf/chi/WerrlichNDYLN18 }} ==Design Recommendations for HMD-based Assembly Training Tasks== https://ceur-ws.org/Vol-2082/paper_9.pdf
AR in the Industry                                                                        SmartObjects '18, in conjunction with CHI '18, Montreal, Canada




                                                   Design Recommendations for HMD-
                                                   based Assembly Training Tasks

                      Stefan Werrlich                      Carlos Emilio Franco Yanez           Abstract
                      BMW Group                            University ITESM                     In the last few years, head-mounted displays (HMDs)
                      Stefan.Werrlich@bmw.de               cyfranco19@hotmail.com               received a growing amount of attention by the scientific
                                                                                                community, especially in the industrial domain. Due to
                                                                                                its possibility to work hands-free while providing the
                      Phuc-Anh Nguyen                      Carolin Lorber                       user with necessary augmented information, HMDs can
                      BMW Group                            BMW Group                            enhance the quality and efficiency of assembly and
                      Phuc-Anh.Nguyen@bmw.de               Carolin.Lorber@bmw.de                maintenance tasks. Offering tailored information
                                                                                                requires knowledge about how to design and present
                                                                                                augmented reality (AR) content. However, design
                      Austino-Davis Daniel                 Gunther Notni                        guidelines especially for assembly training tasks as well
                      BMW Group                            Technical University Ilmenau         as usability evaluations are very limited. In this paper,
                      Austino-Davis.Daniel@bmw.de          Gunther.Notni@tu-ilmenau.de          we want to overcome this limitation by introducing an
                                                                                                application as well as 10 design recommendations for
                                                                                                HMD-based assembly training tasks. Furthermore, we
                                                                                                execute a user study with15 participants using an
                                                                                                engine assembly training task to evaluate the software
                                                                                                usability and present results from the system usability
                     Copyright © 2018 for this paper held by its author(s). Copying permitted   scale (SUS) questionnaire, the AttrakDiff as well as the
                     for private and academic purposes.                                         NASA task load index (NASA-TLX) questionnaire.

                                                                                                Author Keywords
                                                                                                Augmented Reality; Assembly; Evaluation; Head-
                                                                                                Mounted Displays; Training; Usability.

                                                                                                ACM Classification Keywords
                                                                                                H.5.2 [Information interfaces and presentation (e.g.,
                                                                                                HCI)]: User Interfaces




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                     Introduction                                                     section 6. A brief discussion and summary follows at
                     Augmented Reality (AR) becomes a part of our daily               the end of this paper in section 7.
                     lives. Several applications for smartphones and tablets
                     are already being used by millions of people.                    Related Work
                     Augmented information are designed to improve                    Design Guidelines are helpful advices for developers
                     communication, enhance human skills and some of                  and designers. They provide instructions on how to
                     them are just for fun. Hand-held devices and projectors          adopt specific design principles such as controllability,
                     are typically used to display superimposed information           learnability or customizability. Software design
                     [1]. In the last years, head-mounted displays (HMDs)             recommendations such as the DIN EN ISO 9241-110
                     received growing interest by researchers in the                  [5], Shneidermans 8 Golden Rules of Interface Design
                     industrial domain because they offer a hands-free                [6] and the 10 usability heuristics for user interface
                     usage and help to increase the quality and efficiency of         design by Jakob Nielsen [7] are often used for general
                     assembly and maintenance tasks [2; 3]. In order to               software development. Specific guidelines for
                     design a suitable AR application for manual procedural           projection-based AR are presented by Funk [8]. Eight
                     tasks, researchers have to know the optimal                      principles, i.e. hands-free usage and personalized
                     information visualization for different devices. Our             feedback, were gained during a four year project using
                     research is focusing on assembly training tasks because          assistive systems for impaired workers. Further specific
                     they are very important for the automotive industry.             recommendations, especially for assembly and
                     Well executed training must be designed efficiently to           maintenance training tasks were published by Webel
                     ensure a good knowledge transfer whereby optimal                 [9]. Principles such as mental model building, haptic
                     process and product quality is guaranteed. However,              hints, visual aids and passive learning were introduced
                     design guidelines for HMD-based applications as well as          and focused on acquiring assembly and maintenance
                     comprehensive usability evaluations are still missing            skills which is our focus as well. However, until now it is
                     [4]. We want to close this gap by providing the                  still uncertain how to visualize augmented information
                     following contributions. The second section aims to give         efficiently using head-mounted displays (HMDs).
                     a brief overview of the related work. Our patented               Scientific contributions in that field are very rare and
                     application is introduced and described in section 3. We         limited to just a few [10]. We want to overcome this
                     aim to set this application as the optimal standard for          limitation by giving a first suggestion in the next
                     information visualization using HMDs for assembly                chapter.
                     training tasks. We execute a user study with 15
                     participants to assess the usability of our application.         Application
                     Detailed information about the experiment are given in           This section provides a brief overview of our patented
                     section 4 and section 5. Due to our gained knowledge             application. We describe the relevant functionalities and
                     during the application development and assessment,               show our user interface design. The application was
                     we extrapolate and present 10 design                             created using Photoshop for the interface design and
                     recommendations for HMD-based assembly training in               Unity3D for the front-end programming. This




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                                         multimodal application consists of six features with               12]. We added an animated arrow to visualize the end
                                         intuitive icons (Figure 1).                                        of the tunnel. The user can use this augmented tunnel
                                                                                                            to find the correct parts in the shelf. This solution
                                                                                                            avoids picking mistakes and improves the training
                                                                                                            performance due to part search no longer being
                                                                                                            required. Another feature provides superimposed
                                                                                                            animated 3D information using an outline shader
                                                                                                            (Figure 4). The outline visualization is sufficient to
                                                                                                            recognize the part’s geometry and position. Additional
    Figure 2: Superimposed 3D data                                                                          arrows show the screw positions. We highly
    of an engine part visualized using                                                                      recommend this visualization technique because it
    a head-mounted display.                                                                                 allows to assemble the relevant part without any
                                                                                                            superimposition problems. A visualization such as in
                                                                                                            Figure 2 may affect the assembly process because the
                                                                                                            real part is hard to recognize due to the strong color
                                                                                                            rendering.
                                         Figure 1: User Interface for assembly training tasks using
                                         head-mounted displays. 3D feature is activated.                    The last feature is a video (Figure 5) whereby the user
                                         The trainee can choose between six modalities for each             receives detailed information about the current task.
                                         assembly step. A sound feature provides clear auditory             Watching a video with an HMD observing someone
                                         instructions about the current task. Another feature               performing a task facilitates task transfer. We designed
    Figure 3: Augmented Tunnel
                                         visualizes superimposed static 3D data of the                      the video feature similar to a regular video player. A
    Guidance for picking tasks.                                                                             play and pause button enables the user to have
                                         corresponding part (Figure 2). This feature may help to
                                         learn the position and orientation of the related part.            complete control over the feature. The progress bar
                                         When selecting a feature, the icon-color changes to                supports the user in building a mental representation of
                                         green and a click sound occurs which gives the user an             the task. Additional context information such as a
                                         immediate feedback of his action. Every feature can be             progress bar in the middle of the interface as well as
                                         activated and deactivated by either clicking or using the          the task overview when selecting the brand icon (Figure
                                         voice command ‘select’.                                            6) supports mental model building and strengthens the
                                                                                                            training transfer. The user receives information about
                                         The text feature provides annotations about the current            the finished, the upcoming and the current task. Users
                                         task showing the relevant parts, the activity (e.g.                are further able to switch between the assembly steps
                                         assembly or plug), the associated materials such as                either by clicking the left or right arrow as well as using
    Figure 4: 3D part visualization
    using an outline shader and          screws and the needed tools. We also implemented a                 the task overview or using the voice commands ‘next’
    arrows to highlight the screw        Bezier-curve (Figure 3) which was found to be a good               and ‘back’. This concept offers user control and avoids
    positions.
                                         solution for picking guidance in previous studies [11;




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                                          a simple step-by-step guidance which is not favorable              active and the user is able to continue the assembly
                                          for training tasks.                                                procedure. We used this approach because it offers
                                                                                                             several advantages. Backward fading can decrease the
                                          According to the concept of learning introduced by Fitts           cognitive workload, enhance the learning transfer and
                                          and Posner [13], we structured our application using               improves the initial performance of manual procedural
                                          different learning stages. Information are gradually               task [15].
                                          reduced during the training. All features are available in
                                          the tutorial level. The first level is made for exploring          Evaluation
                                          the task, the application as well as familiarizing with            We conducted a user study with 15 participants to
     Figure 5: Augmented Reality
     video player for assembly training   using a HMD. Two features with the strongest guidance              evaluate the usability of our HMD-based software for
     tasks.                               were blocked in the beginner level. The augmented                  assembly training tasks. This section describes the
                                          tunnel and the outline features were equipped with a               study design, explains the procedure, introduces the
                                          bolt sign to visualize the restriction (Figure 7). When            hardware setup, gives a detailed information about the
                                          clicking on one of the restricted feature, the avatar (we          participants and reports the results of our
                                          named Embly) loses one of its seven lives (Figure 8).              measurements.
                                          This game-based learning approach aims to motivate
                                          the user finishing the task autonomous using the                   Design
                                          available features without killing Embly. Two more                 To evaluate the usability of our training software for
                                          functions, the 3D feature as well as the video function            assembly training tasks, we designed an experiment
     Figure 6: Assembly task              are additionally blocked in the intermediate level. Every          with three groups and different knowledge backgrounds
     overview.
                                          feature is restricted in the expert level. Only a default          in AR and assembly processes (independent variables)
                                          audio with information about the underlying task is                following a between-subject design recommended by
                                          provided for each step.                                            Nielsen [16]. Measuring the usability of a software
                                                                                                             includes the assessment of effectivity, efficiency and
                                          Additionally, we used a single backward fading learning            user satisfaction variables [17]. To gather the
                                          approach which was found to be effective for learning              effectivity of our training software we measured the
                                          by Renkl [14]. This means, the last step is faded out in           dependent variables assembly (AM) and picking
                                          the tutorial level, the last two steps in the beginner             mistakes (PM), self-corrected assembly (CAM) and
                                          level, the last three in the intermediate level and the            picking mistakes (CPM) as well as correction by help for
                                          last four steps in the expert level. The user is asked to          the assembly (CBHA) and picking (CBHP). We further
                                          select the correct part before receiving information               verify the backward fading questions (BWF) allocating
     Figure 7: Restricted User
     Interface in the Beginner Level.     about the task (Figure 9). At this time, all six features          either one point (correct answer) or zero points (wrong
                                          are blocked. Participants receive a visual (green color)           answer). As dependent variable for the efficiency, we
                                          and an auditory feedback as soon as they select the                measured the tutorial level completion time (TLCT), the
                                          right part. The part is marked red in color if the user            beginner level completion time (BLCT), the
                                          selects the wrong part. Afterwards, all features become            intermediate level completion time (ILCT) as well as the




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                                       expert level completion time (ELCT). Additionally, we            Procedure
                                       collect user satisfaction data using the extended system         Through a public invitation, we acquired five office
                                       usability score (SUS) according to Bangor [18] as well           employees, five assembly employees as well as five AR-
                                       as the AttrakDiff questionnaire [19]. We also used the           experts in preparation of our study. All participants
                                       NASA Task Load Index (NASA-TLX) to rate the                      were informed in advance to bring safety boots and
                                       perceived workload during the experiment [20]. We                safety gloves. We initially made all participants familiar
                                       measured six dependent variables, the mental workload            with the environment since the test environment and
                                       (MWL), the physical workload (PWL), the temporal                 the assembly task was new for every participant. At
                                       workload (TWL), the user performance (UP), the user              first, we explained the assistive system and informed
    Figure 8: User activated a         effort (UE) as well as the user frustration (UF). A high         every participant that their participation is voluntary.
    restricted feature wherby Embly    cognitive workload may harm the learning process                 We further told them to inform us whenever they feel
    loses one of its seven lives.
                                       because fewer cognitive resources are available which            uncomfortable so we can abort the experiment
                                       are needed to store relevant information in the                  immediately. Afterwards, we explained the purpose of
                                       procedural memory.                                               the usability study. After explaining the ambition of the
                                                                                                        experiment, we measured and adjusted the user’s
                                       Apparatus                                                        interpupillary distance (IPD) which is important for the
                                       For our experiment, we used a Microsoft HoloLens HMD             visual quality. Holograms may appear unstable or at an
                                       to display our training software, providing all assembly         incorrect distance when using an incorrect IPD. We
                                       instructions. In contrast to other researchers who used          showed how to adjust the HoloLens and started with
    Figure 9: Embly asked the user
                                       low complex Lego Duplo assembly task to evaluate                 the Microsoft Learn Gestures Application to familiarize
    to select the correct part using
    backward fading.                   their solutions [21], we used a real engine assembly             our participants with the interaction modalities. Once
                                       task. The test environment was build referring to the            the participants felt confident using the HMD, we kindly
                                       production workplace (Figure 10). The workplace                  asked our users to start our training application. All
                                       consists of three areas. A shelf area providing all the          participants were asked to complete the tutorial level at
                                       parts and screws necessary for the assembly process.             first, continuing with the beginner, intermediate and
                                       All tools can be found in the tool area. The assembly            expert levels. Users had to work through 15 assembly
                                       area includes a driverless transport system (DTS)                steps in each level. The assembly sequence between
                                       mounted with a six-cylinder engine. We used an                   the levels was not modified. Only the provided
                                       assembly training task with 15 steps following                   information were reduced. Between each level, we
                                       production specification. The training contains low              disassembled the engine back to its initial state. During
                                       complexity tasks such as screwing a lifting eyebolt but          that time, participants were asked to have a 10
                                       also high complexity tasks such as installing, screwing          minutes break. We offered various sweets and soft-
    Figure 10: Work environment for    and plugging a harness.                                          drinks to generate a pleasant break. During the study
    the engine assembly training.                                                                       we measured the time for each level, assembly and
                                                                                                        picking mistakes, self-corrected mistakes, corrections
                                                                                                        by help as well as the backward fading questions. To




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                                       measure the training time between each assembly we               SD = 0.00) and medium experience with assembly
                                       paired our application with a database using a WiFi              processes (M= 2.00; SD = 0.63). All participants were
                                       internet connection. This approach guarantees a                  capable to understand, read and write the German
                                       reliable data collection. After finishing the fourth and         language since the entire auditory instructions provided
                                       last level, participants were asked to rate the training         by our software as well as the questionnaires were in
                                       software using three established questionnaires. We              German.
                                       used an extended SUS to evaluate the usability of our
                                       software. Participants had to finish a 10 item                   Results
                                       questionnaire using a five options Likert scale ranging          There was no significant difference between the
                                       from strongly agree to strongly disagree. The second             assembly training times (Table 3). The Shapiro Wilk
      Table 1: Assembly mistakes       questionnaire (AttrakDiff) aims to determine the                 Test showed a normal distribution for TLCT, ILCT and
      during the assembly training
                                       pragmatic and hedonic quality. The questionnaire was             ELCT and non normal distribution for BLCT (p=.02). We
     using HMD-based instructions.
                                       finished with the NASA-TLX to assess the cognitive               used a one way ANOVA which showed no a statistically
                                       workload during the training.                                    significant difference for the TLCT (F(2,12)=.478;
                                                                                                        p=.631) and ELCT (F (2,12)=1,189; p=.388). The ILCT
                                       Participants                                                     did violate the variance homogeneity (p=.034).
                                       We invited 15 participants (13 male, 2 female) for our           Therefore we used the Welch Test which showed no
                                       user study following Nielsen who recommends                      significant difference for the ILCT (F(2, 7,425)=1,855;
                                       performing a usability study using three groups with             p=.222). The Kruskall Wallis Test for BLCT also showed
                                       five users each [16]. The participants were aged from            no significant difference (χ² (2)=.08 ; p=.961) between
                                       21 to 42 (M = 30.06; SD = 6.20). Five of them were               the groups.
    Table 2: Picking mistakes during
                                       office employees, five were assembly employees
    the assembly training using HMD-
           based instructions.         working in the BMW Group production and five were                During the study, all three groups made a few errors
                                       AR-experts with at least 5 years background in AR. We            (Table 1; 2) but there was so significant difference
                                       asked each group for their AR and assembly                       between the groups. The Shapiro Wilk Test did show a
                                       background using a five item Likert scale ranging from           non-normal distribution for all variables (AM, PM, CAM,
        Table 3: Average level
                                       much experience to few experience. Much experience               CPM, CBHA, CBHP). We used the Kruskall Wallis Test to
      completion times in seconds.
                                       were scored with 4 points, few experience with 0                 find difference between the variables but the test
                                       points. Office employees stated to have no background            showed no significant difference for AM (χ² (2)=1,227 ;
                                       in AR (M= 0.20; SD = 0.40) and medium experience                 p=.541), for PM (χ² (2)=1,745 ; p=.418), for CAM (χ²
                                       with assembly processes (M= 1.60; SD = 1.35). The                (2)=.162 ; p=.922), for CPM (χ² (2)=1,536 ; p=.458),
                                       assembly workers had a strong background in assembly             for CBHA (χ² (2)=.560 ; p=.756) and for CBHP (χ²
                                       processes since it’s their daily routine (M = 3.80; SD=          (2)=.126 ; p=.939) between the groups. We also found
                                       0.40) but their knowledge about AR was limited (M =              no significant difference for BWF (χ² (2)=3,960 ;
                                       0.40; SD = 0.49). In contrast to that, all AR-experts            p=.138).
                                       stated to have a strong background in AR (M = 4.00;




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                                        We used the NASA-TLX to measure the mental                        Design Simple.
                                        workload during the experiment but there was no                   We highly recommend to use a simple, clear
                                        significant difference for the six subscales between the          understandable, consistent application design. Low
                                        groups. The Shapiro Wilk Test did show a non-normal               complexity designs and uniform colors help to reduce
                                        distribution for PW (p=.029) and TWL (p=.038). The                the cognitive workload which improves the training
                                        Kruskall Wallis Test showed no significant difference for         transfer. However, visual complexity increases the
                                        PW (χ²(2)=1,831; p=.40) and TWL (χ²(2)=2,964;                     brain activity and therefore the cognitive workload
                                        p=.227) between the groups. The variables MWL, UP,                which harms the procedural memory.
                                        UE, UF showed a normal distribution and the one way
                                        ANOVA showed no a statistically significant                       Enable users to control the software.
                                        difference for MWL (F(2,12)=2,406; p=.132), for UP                Guiding a user step-by-step through a procedural task
                                        (F (2,12)=.421; p=.666), UE (F (2,12)=2,983;                      improves the initial performance but may have an
   Figure 11: AttrakkDiff result with   p=.089), UF (F (2,12)=.097; p=.908).                              adverse effect on the training transfer. Users might not
   a pragmatic quality of 1.63 and a                                                                      be able to repeat a task without having the support
   hedonic quality of 1.40 for n=15.
                                        The results from the SUS also showed no significant               from an assistive system. Instead of just guiding a user
                                        difference (F(2,12)=.425; p=.663) between the groups.             through a task, they should have full control of the
                                        Nine participants stated that the application was                 application. Users are able to activate and deactivate
                                        ‘excellent’, six of them said it was ‘good’. The SUS              different features, switching between next and previous
                                        showed an average score of 90.5 (M= 90.5; SD= 4.76)               assembly steps as well as different levels of difficulty at
                                        which indicates a high user satisfaction. Additionally,           any time, when using our software. This allows users to
                                        we asked all participants to rate the hedonic (HQ) and            work self-paced without feeling like a robot.
                                        pragmatic quality (PQ) of our software using the
                                        AttrakDiff questionnaire. Results indicate a PQ of 1.63           Provide multimodal feedback.
                                        with a confidence of 0.25 and a HQ of 1.40 with a                 Humans are used to multimodal feedback since it is
                                        confidence of 0.38. Users desire this application for             provided by a lot of technical systems in our daily lives
                                        future use in assembly trainings (Figure 11).                     (e.g. visual and sound feedback is provided when
                                                                                                          pressing a button in an elevator). Adapting familiar
                                        Recommendations                                                   feedback approaches to new technologies such as
                                        Based on the experiences we gained from using our                 HMDs helps to familiarize new users in a shorter
                                        HMD-based application with different user groups, we              amount of time. Furthermore, the combination of
                                        propose 10 recommendations for designing HMD-based                different modalities such as visual, auditory or tactile
                                        assembly training tasks. We also believe that these               feedback can improve the learning transfer through
                                        guidelines are generic and easily transferable to other           stimulating various human information channels.
                                        procedural tasks and different domains (e.g. learning a
                                        surgery procedure) which could help designers and
                                        researchers to create more meaningful applications.




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                     Offer different user modes.                                      Add context information.
                     Providing a wide range of information at the beginning           Adding context information can help users to build and
                     of a learning process helps novice users gather                  strengthen a global picture of a task. Having a strong
                     essential information of the task. Our evaluation                mental model of a procedure allows someone to
                     revealed that once users completed the tutorial level,           perform a task efficiently without requiring support
                     they become much more familiar in using the software             from an assistive system (e.g. HMD). Due to our user
                     modalities as well as performing basic movements                 study, we recommend using progress bars for
                     which indicates the time improvement in Table 3. At              visualizing step-by-step progresses as well as when
                     this point, information should be gradually reduced by           implementing video players to present the length of a
                     not frustrating users with too much unnecessary                  video. A complete task overview was also found to be
                     information. We recommend offering different user                helpful by our participants for building a global picture
                     modes ranging from a tutorial to an expert mode using            of the assembly training task.
                     various amounts of information. This concept allows
                     completely novice employees as well as experienced               Integrate gamification elements.
                     users to use a software product in accordance to their           Assembly processes are often boring and monotonous
                     skill level.                                                     for many employees. When it comes to learning new
                                                                                      procedures, the majority are willing to acquire new
                     User voice interaction.                                          knowledge but they wish more fun during the training
                     Executing manual procedural task requires hands-free             since it takes a lot of time and is very serious. Game-
                     usage which is usually realized when using a HMD.                based learning approaches which are already
                     Additionally, developers should take into account that           widespread in schools for teaching kids might help to
                     extra effort as well as limitations in performing a task         improve assembly trainings. Previous studies already
                     should be avoided when designing interaction concepts.           stated that providing self-quantified information such
                     Therefore, we suggest using voice interaction due to             as errors and time, combined with gamification
                     two facts. Most of the time, users carry parts and tools         elements can enhance work processes [23]. Our
                     when performing assembly tasks. They should be able              participants revealed that Embly is cute and motivates
                     to interact with the HMD without using their hands               them to finish the assembly training successfully.
                     which can be realized using voice interaction. Through           Designing our application according to a game was also
                     our study, we also learned that gesture interaction,             found to be very enjoyable by our participants. We also
                     especially the HoloLens Airtap was hard for many                 believe that the attractiveness of assembly jobs can be
                     participants since it’s an unnatural movement. More              increased for younger people when providing innovative
                     natural and intuitive gesture interaction concepts may           technologies such as HMDs in combination with game-
                     help to overcome this limitation in future [22].                 based learning applications.




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                                      Present multimodal information.                                   when presenting animated 3D parts. While watching a
                                      When analyzing the click rates of our application, we             looped animation of the assembly process, users are
                                      found differences between users and specific user                 able to install the part simultaneously. Rendering only
       Table 4: Feature click rates
      during the assembly training.   groups (Table 4). Most of our participants tend to use            full-color shader parts while wearing a HMD might
                                      traditional, familiar media such as watching a video or           bother users executing the assembly process because
                                      reading a text. On the other side, some participants              real parts are difficult to recognize. Users might tend to
                                      also preferred using three-dimensional content.                   watch underneath the HMD to accomplish the assembly
                                      Therefore, providing the opportunity to choose between            process.
                                      different types of information will help many users
                                      finish an assembly task successfully. Additionally,               Discussion and Conclusion
                                      offering multimodal information can enhance the                   In this paper, we introduced a novel concept for
                                      training transfer.                                                assembly training task using HMDs. According to the
                                                                                                        requirements for industrial killer applications introduced
                                      Build a clean multilayered architecture.                          by Navab [24], we build a reliable, scalable, user
                                      People are familiar working with multilayered mobile              friendly killer application for real engine assembly
                                      phone applications. Each layer contains different                 training tasks and described every feature in detail. An
                                      information and functionalities. Taking this into account         experiment with 15 participants, divided into three
                                      when developing applications for HMDs can help novice             groups with different skill levels, were executed to
                                      users to become adjusted to a new software and                    evaluate the usability of the software. Results regarding
                                      technology very fast. We adapted this approach and                effectivity, efficiency and user satisfaction variables
                                      designed a clean multilayered software for assembly               showed no significant differences between the three
                                      training tasks. Only the UI (Figure 1) is visualized              groups. One reason for that might be the low number
                                      permanently, all other functionalities and information            of participants. Therefore, we argue that everyone can
                                      are hidden under sublayers, selectable on demand. We              use this application, no matter which skill level or
                                      recommend using this concept since all of our                     knowledge background someone has. Due to that fact,
                                      participants liked it.                                            we have created a standard tool for assembly training
                                                                                                        task which ensures a consistent educational result. All
                                      Visualize different 3D content.                                   participant enjoyed using the HMD-based application
                                      Superimposed three-dimensional content supports                   proven by the high SUS of 90.5 and the result from the
                                      trainees in learning the position and orientation of a            AttrakkDiff. Based on the experiences during the
                                      specific part as well as improves the spatial perception.         evaluation, we proposed 10 design recommendations
                                      Providing additional animations not only helps to                 for HMD-based assembly training. These principles can
                                      understand what and where to assemble, it also shows              be adopted by other researches to create a successful
                                      how to assemble a specific part. Therefore, we                    training application. Considering future work, we want
                                      recommend using different 3D augmented reality                    to evaluate our application with a larger amount of
                                      content. We further suggest using an outline shader               participants by measuring the trainer transfer.




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                     Acknowledgements                                                   [6]   Shneiderman, Ben (1998): Designing the user
                     We thank all participants for their unaffordable input and               interface: Strategies for effective human-
                     BMW, for helping and providing with the tools, spaces                    computer interaction. ISBN: 0201694972.
                     and funding to realize and complete this project
                     successfully.                                                      [7]   Nielsen, Jakob; Molich, Rolf (1990): Heuristic
                                                                                              evaluation of user interfaces. In: Chew, Whiteside
                     References                                                               (Hg.) 1990 – Proceedings of the SIGCHI
                     [1]   Büttner, Sebastian; Mucha, Henrik; Funk, Markus;                   conference, S. 249–256. DOI:
                           Kosch, Thomas; Aehnelt, Mario; Robert,                             10.1145/97243.97281.
                           Sebastian; Röcker, Carsten (2017): The Design
                                                                                        [8]   Funk, Markus; Kosch, Thomas; Kettner, Romina;
                           Space of Augmented and Virtual Reality
                                                                                              Korn, Oliver; Schmidt, Albert (2016): motionEAP:
                           Applications for Assistive Environments in
                                                                                              An Overview of 4 Years of Combining Industrial
                           Manufacturing. In: Proceedings of the 10th
                                                                                              Assembly with Augmented Reality for Industry
                           International Conference on PErvasive
                                                                                              4.0. In: Proceedings of the 16th international
                           Technologies Related to Assistive Environments,
                                                                                              conference on knowledge technologies and data-
                           S. 433–440. DOI: 10.1145/3056540.3076193.
                                                                                              driven business.
                     [2]   Hou, Lei; Wang, Xiangyu; Bernold, Leonhard;
                                                                                        [9]   Webel, Sabine; Bockholt, Ulrich; Engelke, Timo;
                           Love, Peter E. D. (2013): Using Animated
                                                                                              Gavish, Nirit; Tecchia, Franco (2011): Design
                           Augmented Reality to Cognitively Guide Assembly.
                                                                                              Recommendations for Augmented Reality based
                           In: Journal of Computing in Civil Engineering, S.
                                                                                              Training of Maintenance Skills. In: Recent Trends
                           439–451. DOI: 10.1061/(ASCE)CP.1943-
                                                                                              of Mobile Collaborative Augmented Reality
                           5487.0000184.
                                                                                              Systems, S. 69–82. DOI: 10.1007/978-1-4419-
                     [3]   Hořejší, Petr (2015): Augmented Reality System                     9845-3_5.
                           for Virtual Training of Parts Assembly. In: Procedia
                                                                                        [10] Werrlich, Stefan; Eichstetter, Elisabeth; Nitsche,
                           Engineering 100, S. 699–706. DOI:
                                                                                             Kai; Notni, Gunther (2017): An Overview of
                           10.1016/j.proeng.2015.01.422.
                                                                                             Evaluations Using Augmented Reality for Assembly
                     [4]   Wang, X.; Ong, S. K.; Nee, A. Y. C. (2016): A                     Training Tasks. In: International Journal of
                           comprehensive survey of augmented reality                         Computer and Information Engineering, S. 1074–
                           assembly research. In: Advances in                                1080.
                           Manufacturing, S. 1–22. DOI: 10.1007/s40436-
                                                                                        [11] Bjoern Schwerdtfeger (2012): Pick-by-vision:
                           015-0131-4.
                                                                                             Bringing HMD-based Augmented Reality into the
                     [5]   Ergonomics of human-system interaction - Part                     Warehouse. ISBN: 978-3832526276.
                           110: Dialogue principles (ISO 9241-110:2006);
                                                                                        [12] Biocca, F.; Tang, A.; Owen, C.; Fan, Xiao (2006):
                           Deutsche Fassung EN ISO 9241-110:2006.
                                                                                             The Omnidirectional Attention Funnel: A Dynamic




                                                                                                                                                   67
AR in the Industry                                                             SmartObjects '18, in conjunction with CHI '18, Montreal, Canada




                          3D Cursor for Mobile Augmented Reality Systems.            [19] Hassenzahl, Marc; Burmester, Michael; Koller,
                          In: Proceedings of the 39th Annual Hawaii                       Franz (2003): AttrakDiff: Ein Fragebogen zur
                          International Conference on System Sciences                     Messung wahrgenommener hedonischer und
                          (HICSS'06), S. 22c-22c. DOI:                                    pragmatischer Qualität. In: Szwillus (Hg.) 2003 -
                          10.1109/HICSS.2006.476.                                         Mensch & Computer 2003, S. 187–196. DOI:
                                                                                          10.1007/978-3-322-80058-9_19.
                     [13] Fitts, P.M; Posner, M.I (1967): Human
                          Performance. In: Belomnt, CA: Brooks/Cole.                 [20] Hart, Sandra G.; Staveland, Lowell E. ():
                                                                                          Development of NASA-TLX (Task Load Index):
                     [14] Renkl, A.; Atkinson, R.K; Maier, U.H; Staley, R.
                                                                                          Results of Empirical and Theoretical Research. In:
                          (2002): From example study to problem solving:
                                                                                          Meshkati, Hancock (Hg.) 1988 - Human Mental
                          Smooth transitions help learning. In: Journal of
                                                                                          Workload, S. 139–183. DOI: 10.1016/S0166-
                          Experimental Education, S. 293–315.
                                                                                          4115(08)62386-9.
                     [15] Eiriksdottir, E.; Catrambone, R. (2011):
                                                                                     [21] Loch, Frieder; Quint, Fabian; Brishtel, Iuliia
                          Procedural Instructions, Principles, and Examples:
                                                                                          (2016): Comparing Video and Augmented Reality
                          How to Structure Instructions for Procedural Tasks
                                                                                          Assistance in Manual Assembly. In: 2016 12th
                          to Enhance Performance, Learning, and Transfer.
                                                                                          International Conference, S. 147–150. DOI:
                          In: Human Factors: The Journal of the Human
                                                                                          10.1109/IE.2016.31.
                          Factors and Ergonomics Society, S. 749–770.
                          DOI: 10.1177/0018720811419154.                             [22] Funk, Markus; Kritzler, Mareike; Michahelles,
                                                                                          Florian (2017): HoloLens is more than air Tap. In:
                     [16] Nielsen, Jakob; Landauer, Thomas K. (1993): A
                                                                                          IoT '17 Proceedings of the Seventh International
                          mathematical model of the finding of usability
                                                                                          Conference on the Internet of Things, S. 1–2.
                          problems. In: Arnold, van der Veer et al. (Hg.)
                                                                                          DOI: 10.1145/3131542.3140267.
                          1993 - Proceedings of the SIGCHI conference, S.
                          206–213. DOI: 10.1145/169059.169166.                       [23] Korn, Oliver; Muschik, Peter; Schmidt, Albrecht
                                                                                          (2016): Gamification of Production? A Study on
                     [17] Ergonomische Anforderungen für Bürotätigkeiten
                                                                                          the Acceptance of Gamified Work Processes in the
                          mit Bildschirmgeräten, Teil 11: Anforderungen an
                                                                                          Automotive Industry. In: Advances in Affective
                          die Gebrauchstauglichkeit - Leitsätze; Deutsche
                                                                                          and Pleasurable Design, S. 433–445. DOI:
                          Fassung EN ISO 9241-11:1998.
                                                                                          10.1007/978-3-319-41661-8_42.
                     [18] Bangor, Aaron; Kortum, Philip T.; Miller, James T.
                                                                                     [24] Navab, Nassir (2004): Developing killer apps for
                          (2008): An Empirical Evaluation of the System
                                                                                          industrial augmented reality. In: IEEE Computer
                          Usability Scale. In: International Journal of
                                                                                          Graphics and Applications, S. 16–20. DOI:
                          Human-Computer Interaction, S. 574–594. DOI:
                                                                                          10.1109/MCG.2004.1297006.
                          10.1080/10447310802205776.




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