Prerequisites for Automatically Creating Work Instructions in Augmented Reality for Assembly of Gripen E : a case study at Saab Aeronautics

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Linköping University | Department of Management and Engineering - IEI Master Thesis, 30 hp | Master’s Programme in Mechanical Engineering – Manufacturing Engineering

Spring 2020 | LIU-IEI-TEK-A--20/03822—SE

Prerequisites for Automatically Creating

Work Instructions in Augmented Reality

for Assembly of Gripen E

- a case study at Saab Aeronautics

Skander Kamran Alexander Mäkelä

Supervisor: Martin Hochwallner

Examiner: Luis Ribeiro

Linköping University SE-581 83 Linköping, Sweden 013-28 10 00, www.liu.se

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Abstract

This thesis work has been carried out at the company Saab AB Aeronautics, which manufactures the military aircraft Gripen E. Today, the company uses 3D work instructions for assembly of Gripen E, which is displayed on a computer screen for the shop floor workers. The company has an interest in investigating whether today's work instructions can be visualized in an Augmented Reality interface by reusing available data. This work has been limited to studying wire harness assembly, which is a main part of the final assembly. The methodology case study in combination with the method Requirements Engineering has been used to analyze the company's possibilities. Data collection has been conducted with internal interviews, studying internal materials and internal courses. The result chapter contains two parts, where the first part presents a situation analysis of how today's work instructions are created in the software DELMIA and what data that is needed. The second part presents a requirements specification for an Augmented Reality Work Instruction for assembly of Gripen E. In the discussion, the situation analysis is compared with the requirements to answer which data that could be reused for creating Augmented Reality Work Instructions and what challenges that may arise. This study shows that the company has prerequisites for creating work instructions in Augmented Reality, as there is available data containing 3D models structured according to an assembly sequence with associated descriptive information.

Keywords: Augmented Reality, Work Instructions, Assembly Work Instructions, 3D Work Instructions, Process Planning in DELMIA,

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Nomenclature

ARM – Assembly Requirement Model

Describes the requirements for assembly in 3D.

CATIA – Computer Aided Three-dimensional Interactive Application Software used for product design.

DELMIA – Digital Enterprise Lean Manufacturing Interactive Application Software used for process planning.

DPE – DELMIA Process Engineer

Application for overview of the entire process planning. DPM – DELMIA Process Management

Application used for process planning in 3D. EBOM – Engineering Bill of Material

3D models in a product structure with regards to how the product is designed. ER – Engineering Requirements

Part of an ARM or IRM.

ERP – Enterprise Resource Planning

Application used for access the work instructions. FTA – Functional Tolerances and Annotations

Text based information containing dimensions, tolerances, notations, annotations and information required to define the design intent and key features.

GAIS 2 – Global Assembly Instruction Strategies 2

Previous Augmented Reality project founded by Vinnova. GMS – Global Management System

Application used for access the internal standards. HMD – Head Mounted Display

A type of Augmented Reality hardware. IRM – Installation Requirement Model

Describes the requirements for installation in 3D. MBD – Model Based Definition

Work methodology with a product definition in 3D as a master. MBOM – Manufacturing Bill of Material

3D models in an assembly structure with regards to how the product is to be assembled. OL – Operation List

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OP – Operation

Process object in DELMIA, which constitutes a work instruction. PAR – Process Attaches Resource

Resource link type in DELMIA, used when a resource is to be added in a WI-step. PDR – Process Detaches Resource

Resource link type in DELMIA, used when a resource is to be removed in a WI-step. PFPP – Process First Processes Product

Part link type used in DELMIA, used when a part is used for the first time in a WI-step. PP – Product Plan

The main container of the process objects in DELMIA. PPP – Process Processes product

Part link type used in DELMIA, used when a part is to be reused in a WI-step. PRP – Process Removes Product

Part link type used in DELMIA, used when a part is to be removed in a WI-step. PS – Product Structure

Process object in DELMIA, containing manufacturing context. RAM – Requirements Abstraction Model

A model used for structuring the requirements by level of abstraction. RE – Requirements Engineering

A method used in this study for elicitation of requirements. SAAB – Svenska Aeroplan Aktiebolaget

The Company where this master thesis is conducted. TACO – Instruction Innovation for Cognitive Optimization Current Augmented Reality project founded by Vinnova. WI-STEP – Work Instruction Step

One step in the work instruction.

WKC – DELMIA Work Instruction Composer

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Acknowledgement

This master thesis was carried out at Saab Aeronautics in Linköping during the spring term of 2020. Although a pandemic occurred during this period, we are very grateful that the company handled the situation in an excellent way so it did not affect our work. Many thanks to the company’s personnel who have supported us in our work:

 Supervisor, who gave us the opportunity to conduct the master thesis at the department MBD and PDM solutions. Thank you for all your help, we could not have wished for a better supervisor.

 All other personnel at Saab Aeronautics, who helped us, got involved and welcomed us with open arms.

We would also like to thank our supervisor from Linköping University who introduced us to the method Requirements Engineering and for supporting us in our work throughout the period.

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Table of Figures

AN EXAMPLE OF AUGMENTED REALITY WHERE THE REAL WORLD IS COMBINED WITH VIRTUAL OBJECTS. RETRIEVED FROM: HTTPS://UPLOAD.WIKIMEDIA.ORG/WIKIPEDIA/COMMONS/0/0A/ENTRENAMIENTO-INDUSTRIAL-FYWARE.JPG ... 14

AN EXPLANATORY PICTURE SHOWING HOW A NEW SYSTEM CAN BE PLACED IN A CONTEXT WHERE OTHER SYSTEMS CAN AFFECT THE NEW SYSTEM.THE SYSTEMS THAT ARE OUT OF CONTEXT ARE SYSTEMS THAT ARE NOT CONSIDERED TO AFFECT THE NEW SYSTEM. .. 18

OVERVIEW OF THE STUDY PROCESS FLOW, EACH GREY BOX REPRESENTS A PHASE AND INCLUDED ACTIVITIES IN THAT PHASE.THE YELLOW BOX REPRESENTS THE INPUT THAT IS USED IN THE ANALYSIS OF PRE-STUDY ... 21

THIS IS AN EXAMPLE OF HOW THE WORK INSTRUCTIONS CAN BE DISPLAYED FOR THE SHOP FLOOR WORKERS AT THE SHOP FLOOR.IN THE PICTURE TWO WORK INSTRUCTIONS ARE OPENED WITH DIFFERENT TASKS, WHERE EACH WORK INSTRUCTION IS DEDICATED FOR ONE SHOP FLOOR WORKER.RETRIEVED FROM: [HTTPS://MEDIAPORTAL.SAABGROUP.COM/#/ITEMS/23416]COPYRIGHT SAAB AB,HARRI KOSKINEN ... 27

A SIMPLIFIED PICTURE OF HOW THE MBD-METHODOLOGY IS APPLIED AT SAAB AERONAUTICS FOR MANUFACTURING OF GRIPEN E.IT SHOWS WHICH DEPARTMENTS THAT ARE LINKED TO AND USES THE 3D-MODEL PRODUCT DEFINITION.RETRIEVED FROM: [INTERNAL MATERIAL],COPYRIGHT SAAB AB. ... 28

PROCESS PLANNING FLOW FOR CREATING WORK INSTRUCTIONS. ... 29

THE FIGURE SHOWS THE HIERARCHICAL STRUCTURE OF PROCESS OBJECTS THAT BUILD UP A PROCESS IN DELMIA. ... 31

THE FIGURE SHOWS THE PROCESS,PRODUCTS AND RESOURCE (PPR) STRUCTURE TREE, WHERE THE PROCESS OBJECT ARE CREATED AND PARTS AND RESOURCES ARE LOADED.THE PARTS AND RESOURCES ARE NOT YET LINKED TO THE PROCESS STEPS.THE DETAILS SHOWN IN THIS PICTURE IS FROM A LEGO-DEMONSTRATOR AND NOT ACTUAL PRODUCT DATA. ... 31

THE FIGURE SHOWS AN EXAMPLE OF AN ASSEMBLY REQUIREMENT MODEL AND CONSUMED REQUIREMENTS.THE HIGHLIGHTED PARTS REPRESENTS AN ARM, WHICH IN THIS CASE IS FASTENERS.THIS FIGURE IS A SCREENSHOT FROM DELMIA CONTAINING PARTS OF A LEGO-DEMONSTRATOR AND NOT ACTUAL PRODUCT DATA. ... 33

EXAMPLE OF HOW TEXT INFORMATION LINKED TO A WI-STEP IS DISPLAYED FOR THE SHOP FLOOR WORKERS WITH DIFFERENT GENERATED TEXTS.THE INFORMATION IN THESE INSTRUCTIONS ARE FROM A LEGO-DEMONSTRATOR AND NOT ACTUAL PRODUCT DATA. . 34

A3D BASED WORK INSTRUCTION DISPLAYED FOR THE SHOP FLOOR WORKERS AT THE SHOP FLOOR LEVEL... 36

ILLUSTRATION OF HOW AN OP WITH ITS WI-STEPS AND ATTRIBUTES ARE EXPORTED TO THE .XML. ... 38

THE SYSTEM MAP SHOWS TWO DIFFERENT SYSTEMS, THE LEFT SYSTEM IS THE SYSTEM THAT CREATES TODAY'S WORK INSTRUCTION WHICH IS THE NEW SYSTEM’S CONTEXT.THE RIGHT SYSTEM IS THE NEW SYSTEM, WHICH WILL BE AFFECTED BY THE CURRENT SYSTEM. ... 40

TWO DIFFERENT SCENARIOS.THE LEFT IMAGE SHOWS HOW WIRE HARNESSES CAN BE DESIGNED FOR THE FIRST TIME WITHOUT COINCIDING.THE RIGHT IMAGE SHOWS HOW THE WIRE HARNESSES HAVE BEEN DEVELOPED AND ONE MORE WIRE HARNESS HAVE BEEN ADDED, WHERE THEY COINCIDES WITH EACH OTHER. ... 44

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1 Introduction

With an ever increasing technological complexity in the Defence and Aerospace industry, comes higher cost in the development of new products. This has led the focus on and strive to always improve the design and assembly activities [1]. The aeronautic industry is characterized by having low production volumes and complex manual assembly operations. The shop floor workers need to be provided with information about each assembly operation regarding material, process specifications, quality standards and parts to be assembled [2]. A common way to transfer information of how to carry out assembly operations is by describing it in work instructions.

Work instructions is one of the focus areas where Saab continuously strive for

improvements [3].Today, work instructions are viewed by the shop floor worker on a computer

screen. The displayed work instructions are designed in such a way so it provides the shop floor worker with sufficient information needed to perform the assembly operation. The work instructions are all digital and based on a 3D-master model which contains all information needed for assembly of Gripen E, a military aircraft. They are created as a part of the process planning, where the basis for the production operation is defined. In order to stay competitive on the market there is always a strive to improve internal processes at Saab, where new technologies is continuously evaluated of how they could create value for the company. With focus on work instructions multiple projects [4-6] have been started and carried out which has resulted in new implemented solutions. One of the new technologies that has been evaluated is work instructions in Augmented Reality. Augmented Reality is a technique that combines real world with virtual objects [7].

If the work instructions are to be moved to an Augmented Reality interface instead, it may require an adaption of what information that is to be visualized. This is because it will be a whole different way of how the shop floor worker sees and interacts with the interface. There are no current standards at the company of how a work instructions adapted for Augmented Reality should be designed and what information it should contain.

There is a need to find out what data that is needed to create Augmented Reality Work Instructions in a standardized way. The company wishes to reuse as much data as possible from the work instructions when creating Augmented Reality Work Instructions, to allow the current work instructions to be created with the same amount of work for the process planners.

The company has earlier explored the possibilities of implementing work instruction in Augmented Reality. Previous research done by the company has investigated whether it was possible to manually transfer data from the work instructions used today directly into an Augmented Reality interface [4]. The results of this investigation showed that it was possible. However, it was time consuming to do it manually and it was found that some information may not be needed or needs to be adapted for an Augmented Reality Work Instruction.

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1.1 Purpose and Aim

The purpose of this study is to examine the current method Saab Aeronautics uses to create work instructions for assembly of Gripen E. With this, identify what data that is used to create their work instructions and where in their system the data is created. Based on this knowledge, identify what data that is suitable to transfer to a work instruction that will be viewed in an Augmented Reality interface. The aim of this study is to investigate:

 Which potential challenges that the company can face when reusing the current data for creating work instructions in Augmented Reality for assembly of Gripen E.

1.2 Research Questions

In order to reach the formulated aim, this study will be focused on providing an answer to the following Research Questions (RQ).

 RQ(1): What information should be displayed in an Augmented Reality Work Instruction for assembly of Gripen E?

 RQ(2): How can the data used for creating work instructions in the current system be reused for creating Augmented Reality Work Instructions for assembly of Gripen E?

1.3 Deliverables

 The outcome of this study will include a current situation assessment where the focus is to describe the work flow Saab Aeronautics uses when creating the work instructions today. It will also include an identification of where in this system data is created.  A requirement specification of an Augmented Reality Work Instruction that describes

functions it has to contain.

1.4 Studied Case

In order to solve the listed research questions, this study will focus on work instructions used for the assembly of wire harnesses in the final assembly of Gripen E. This case is designed to cover all the relevant areas which is required to reach the aim of this study. This is also done in order to narrow down the project and to help focus on finding out more detailed results of which data that can be reused. The work instructions used in the assembly are created with the same process and therefore it is argued that by analysing the wire harness it can be scaled up for all work instructions for Gripen E. A more detailed description of what a wire harness is, is presented in section 5.1.

1.5 Delimitations

In order to limit the scope of this study, delimitations will consist of:

 No investigation of possible software that can be used to create the Augmented Reality Work Instructions.

 No evaluation of hardware that can be used to visualize the Augmented Reality Work Instruction.

 No suggestions of interface design of the Augmented Reality Work Instructions.  No implementation or testing of the findings.

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2 Background

This chapter serves to provide a short introduction to Saab Aeronautics, which is the company where this master thesis is conducted. The department that is involved in this project and their function at Saab Aeronautics will be explained briefly to provide the reader with an overview of the company. A brief description of the previous project Global Assembly Instructions Strategy 2 (GAIS2) and the project this thesis is a part of will be given.

2.1 Introduction to Saab Aeronautics

Svenska Aeroplan Aktiebolaget (Saab) is a Swedish company that operates worldwide by offering products, services and systems for both the civilian and military markets. The company consists of six different business areas: Aeronautics, Dynamics, Surveillance, Support and Services, Industrial Products and Services and Kockums. In total, Saab has around 16,000 employees worldwide. [8] The business area that this thesis is concerning is Aeronautics, which will hereafter be referred to as Saab, Aeronautics or Saab Aeronautics. One of Saab Aeronautics main areas is the development of the JAS 39 Gripen E, a military aircraft well known worldwide.

This master thesis is conducted in collaboration with Saab Aeronautics’ Model Based Definition (MBD) and Product Data Management (PDM)-Solutions department who are responsible for method development. MBD and PDM-Solutions acts as a support function to other departments at Aeronautics. All departments have their own developed methodology how to carry out and document their work and MBD and PDM-Solutions ensures that their way of working is supported by the correct software/hardware-methodology. For example integration of CAD software and PLM/PDM-systems.

2.2 Global Assembly Instruction Strategies 2 (GAIS2)

Saab Aeronautics has earlier investigated the possibility of implementing work instructions in Augmented Reality. GAIS2 was a project that ran for two years, between 2016 and 2018. Five actors were included in the project: Saab Aeronautics, Combitech, Chalmers University of Technology, Volvo Group Trucks Operation, University of the West, XMReality. The aim of the project was to improve the exchange of information and knowledge within a global production network where the focus was on two areas within assembly work instructions: The creation of work instructions and training and learning for shop floor workers. [4]

The entire project was divided into five work packages where Saab Aeronautics was more involved in work package 1 and 2. The first work package was to implement work instructions in Augmented Reality with the HoloLens hardware and to evaluate the technology. The result of work package 1 showed that it was and is possible to use work instructions in Augmented Reality, but that the technology was not mature enough. [4]

In an interview with one of the project members from Saab Aeronautics, it was explained that they wanted to investigate the possibility of using today's work instructions in Augmented Reality. Saab Aeronautics uses CATIA and DELMIA software to prepare their work instructions where the file formats of the work instructions are .xml and .smg. The .smg file was converted to another file format in order to be readable for the software Unity that was used. This was done because the HoloLens hardware and the software Unity could not load .smg file formats. Unity is the software used for the creation of Augmented Reality in HoloLens. Furthermore, it is explained that it is possible to use today's data for Augmented Reality Work Instructions.

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2.3 Instruction Innovation for Cognitive Optimization (TACO)

The next step for Saab Aeronautics is to further investigate the possibilities with Augmented Reality and therefore a new project has been initiated. The project will be a part of a Vinnova funded collaboration project where several other actors are involved. The main actor in TACO is Chalmers University of Technology, which will analyse work packages provided by the involved actors. One of the overall goals of TACO is to analyse the design of assembly work instruction and production systems closely linked to the production. The purpose of the work package Saab is participating in, is to create a demonstrator of an Augmented Reality Work Instruction. This thesis will serve as the first step in this work package, to investigate in and evaluate the prerequisites Saab Aeronautics has today for implementing and creating work instructions in Augmented Reality.

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3 Literature Review

In this chapter the main findings of the conducted literature study is presented. In this chapter a brief definition of data and information will be presented. It also includes an explanation of Augmented Reality and how it can be used for visualizing work instructions. Lastly, a description of the method Requirements Engineering used in this study is given.

3.1 Data and Information

Data can be considered as information in numerical form and it is presented in a way to allow it to be digitally transmitted of processed. Data are a collection of facts and are form independent, which does not require any evident meaning or sequence of usability when it is presented as raw form. [9]

Information can be defined as the communication or reception of knowledge or intelligence. Data becomes information when it is presented in a way that makes it understandable to a human. In addition to specific, individual definitions, it is of importance to distinguish between what is considered “data” and what is “information” to not cause misinterpretations. In a strict sense, data can simply be a collection of facts, which can exist without any particular meaning or form. However, when this data is converted into a human-readable format, i.e. displayed as “information” depends on the particular tasks, function, and needs of the user. [9]

Two different types of data that are relevant for this thesis are described below:

 META data, which can be explained as “data about data”. The data is structured and describes information about an object. [10]

 Computer Aided Design (CAD) data, used to store 3D models.

3.2 Augmented Reality

Augmented Reality (AR) is a variant of Virtual Reality (VR). Virtual Reality technologies immerse a user completely in a virtual environment where it is not possible for the user to see the real world. In contrast, Augmented Reality makes use of digital or computer generated information and superimposes it in a real-time environment, resulting in a combination of real world with virtual information. The most common use of Augmented Reality is visual where AR supplements reality, rather than completely replacing it. It is also possible to remove information in the real environment with Augmented Reality, through dematerialization or re-materialization. The ability of Augmented Reality is to be able to bring useful information to the visual spectrum in real time. Augmented Reality is not just a single technology, but it is a combination of several technologies for being able to use digital information in a visual sense. [7] In general, the three characteristics of augmented reality are, according to [7]:

 Augmented Reality combines real world with virtual information.  Augmented Reality is interactive in real time.

 Augmented Reality operates and is used in a 3D environment. 3.2.1 Guidelines for Augmented Reality Work Instructions

Augmented Reality has been intensively researched since the 1990's and the first work instruction in Augmented Reality was proposed for manufacturing of an aircraft. Previous work has shown many benefits of using work instructions in Augmented Reality. Compared to traditional work instructions, it has shown that work instructions in Augmented Reality dramatically reduces the number of errors during assembly. Another benefit of using this

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technology combined with work instructions, is that it reduces the time for completing assembly tasks. The physical load is also reduced because neck and head movements are reduced. The benefits of using Augmented Reality with work instructions improves the assembly performance and therefore reduces costs. There are different types of hardware to visualize working instructions in Augmented Reality and in recent years it has become more common with head mounted displays. The reason for that is because it is a hands-free hardware, which means that the shop floor worker has his or her hands free to perform a task. [11]

Figure 1below shows an example of how Augmented Reality can be used in industry, where

the real world is combined with virtual information.

Figure 1. An example of Augmented Reality where the real world is combined with virtual objects. Retrieved from:

https://upload.wikimedia.org/wikipedia/commons/0/0a/Entrenamiento-industrial-Fyware.jpg

In article [12], a study has been conducted with wire harness assembly for commercial aircraft similar to this project. Tests were performed with 50 shop floor workers who interacted with Augmented Reality Work Instructions. Based on the result of the tests, they came up with a certain number of future improvements that one should keep in mind when developing a work instruction for wire harness assembly:

1. Indication of where wire harness start, end and cross. The wire harnesses should have different colour codes for each wire harness as well as symbolic signs of where they start, end and cross.

2. Wireless network to collect and synchronize data, through system servers. 3. Voice interaction support.

4. Trace back between the work instructions to be able to visualize what has been done previously.

5. Provide the shop floor worker with extra support if the shop floor worker works “too long” with a work instruction

6. In order to improve the Augmented Reality interface in the future, measure and analyse the shop floor worker movements through "Gaze-tracking". This means that one could study how the shop floor workers gaze moves during a given time sequence. The

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purpose is to analyses the difference between an experienced and a non-experienced shop floor worker.

7. Visual clarity, to not distract the shop floor workers. This means that the shop floor worker should not have to look away for a better clarity.

In article [13],interviews and observations of shop floor workers where conducted. The authors

studied what a shop floor worker is interested in when assembling an engine with an Augmented Reality Work Instruction. The assembly consisted of a screw operation. Based on the study, there were three future improvements that should be included in an Augmented Reality Work Instruction beside the text-based instruction:

8. Time left of the work cycle time. This means that there should be a ticking clock, showing the remaining time left of the work cycle time.

9. Screw measurement, showing the shop floor worker the applied torque value.

10. Indication of malfunction by means of lighting, when a shop floor worker has mounted something incorrectly.

In article [14], different Augmented Reality hardware are evaluated and these are weighted against each other in order to find the best hardware on the market. However, independent of which Augmented Reality hardware that is used there are important aspects that should be considered in Augmented Reality:

11. Low information content, because the idea is to improve the world, not to block it with a lot of graphical objects for the shop floor worker.

12. Interaction with Augmented Reality must be possible without using hands, since the shop floor worker needs to use his or her hands for the tasks. It could be through voice command, which has proven to work well.

Also in article [15] it is stated that not too much information should be displayed in an Augmented Reality interface. This is because it can affect the cognitive load. The authors also believe that each work instruction should be adapted to the shop floor worker, that is: Depending on the shop floor worker’s experience, it should be possible to choose how much displayed information that is necessary.

According to [16], 4-5 parts of information at the same time displayed in an Augmented

Reality Work Instruction is optimal for training shop floor workers. It also showed that consequences and results could not help the new shop floor worker to perform better.

It is possible to create user-friendly interfaces in Augmented Reality and well suited for factories. In the user-friendly interfaces, colours, text and icons should be visualized to increase the usability. [17]

In article [18] it is stated that verification of proper assembly is important in real-time in industries. The authors found that with the help of Augmented Reality together with additional hardware, control of assembly can be carried out and that the real 3D geometry is consistent with the virtual 3D geometry, through 3D deviation control in real time.

In four articles [19-22] it is described that two different data inputs are needed in order to create work instructions in Augmented Reality. The two inputs are data about the assembly sequence and data consisting of CAD models. The data about the assembly sequence must be structured in a sequential and hierarchical order. In article [19], CAD models are also converted to a lightweight format for creating work instructions in Augmented Reality.

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In Augmented Reality it is necessary that 3D models are related to each other and to the world coordinate. There are different needed coordinate systems in an Augmented Reality system. Two of these coordinate systems are object coordinate system and world coordinate system. Object coordinate system is the three-dimensional coordinate system of the 3D model needed to describe the relationship to a certain other object. World coordinate system is the main coordinate system, where all 3D models will be related to this coordinate system. [23]

There are different types of Augmented Reality and one of them is "marker based". A camera integrated with the hardware detects markers and when specific markers are detected, virtual objects belonging to the marker can be displayed in the real world at their right position. [24]

An article [25] about how CAD data can be used for “market based AR” states that they use a marker as a base marker that fixates the scale and the world coordinate frame origin.

3.3 Requirements Engineering

A system can be explained as a collection of people, software, machine and / or components co-operating in an organized way to achieve a common goal, by fulfilling set requirements [26].

Requirements Engineering is a systematic process that is carried out in system development projects and can be considered as an insurance for successful system development projects. It is a process where the system development involves end users, system architects, developers and test teams. When dealing with requirements, it is primarily about eliciting and documenting the wishes and requirements that different stakeholders have, regarding the new system-to-be. The requirements that are documented results in a specification for the new system. The four main activities in Requirements Engineering are elicitation, documentation, validation and

management. [27]The definition of Requirements Engineering according to M. Glinz [28]:

“A systematic and disciplined approach to the specification and management of requirements with the following goals:

1. Knowing the relevant requirements, achieving a consensus among the stakeholders about these requirements, documenting them according to

given standards, and managing them systematically,

2. Understanding and documenting the stakeholders’ desires and needs, 3. Specifying and managing requirements to minimize the risk of

delivering a system that does not meet the stakeholders’ desires and needs.”

3.3.1 Requirement

The definition of requirement according to C.Rupp [27]:

“A requirement is a statement about an attribute or capability of a product, process or person involved in a process.”

The requirements serves as basis for communication, discussion and argumentation between all parties involved in system development, where the requirements have a substantial impact on the architecture of system-to-be. There are different types of requirements, usually they are

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divided into functional and non-functional requirements. [27] The definition of functional requirement according to M. Glinz [28]:

“A requirement concerning a result of behaviour that shall be provided by a function of a system (or of a component or service).”

The non-functional requirements are the opposite of functional requirements and it is more practical not to use the term “non-functional requirements”. Thus, the non-functional requirements can be further subdivided into [27]:

1. Technological requirements 2. Quality of service requirements 3. Use interface requirements

4. Requirements regarding other deliverables 5. Requirements about required activities 6. Legal and contractual requirements

By defining good requirements, it results in a high quality specification where the goal of the system-to-be becomes realistic. There are thirteen quality criteria that needs to be considered to achieve a good requirement [27]:

1. Comprehensive – Each requirement must be able to fully describe the functionality in itself.

2. Correct – Each requirement must be specified correctly as the author interprets it. 3. Agreed upon – Each requirement must be consistent with the stakeholders in order for

the requirements to be correct and valid.

4. Classifiable concerning its legal obligation – Each requirement must be classified with the level of legal obligation as “shall”, “should” and “will”.

5. Consistent – Each requirement must be non-contradictory to other requirements. 6. Testable – Each requirement must be able to be tested to prove the functionality. 7. Unambiguous – Each requirement must be interpreted in an equal manner, regardless

of the reader.

8. Understandable – Each requirement must be understandable by all readers with a common language.

9. Valid and current – Each requirement must be valid when an influencing factor changes.

10. Implementable – Each requirement must be able to be implemented with defined constraints.

11. Necessary – Each requirement must supply with help to meet the goal of the system. 12. Traceable – Each requirement must be able to be uniquely identified with

requirement-ID.

13. Rated – Each requirement must be able to be ranked in order to prioritize the most important requirements, if there are too many requirements.

3.3.2 Elicitation of Requirements

Requirement elicitation is the process where requirements are collected through communication with stakeholders such as customers, system users and others who are affected or can affect the system. It requires knowledge of the application domain and organization as

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well as the specific problems of the system. This process is not only about asking people what they want, it requires a thorough analysis of the organization, the application domain and how the system is to be used. [29]

There are three different sources from where requirements can be derived, that in one way or another have an impact on the system-to-be. Stakeholders is a source that may consist of individuals or institutions that have direct or indirect impact on the system. The second source is documents that set requirements on the system, where examples of documents could be laws, standards and manuals. The third source is other systems, which can be competing systems, previous systems or neighbouring systems. [30]

Other systems that may affect the new system are defined as the system’s context, which is a source of requirements. The system context are existing systems that must not be affected by the development of the new system. The system context thus has a relation to the new system and is important to define. Other systems that will not have any influence on the new system are considered to be outside the system context and are not necessary to define. [27]

Figure 2 shows an example of how a new system can be placed in a context with other systems that can affect the new system. Systems that are outside the context of the system are considered irrelevant to define.

Figure 2. An explanatory picture showing how a new system can be placed in a context where other systems can affect the new system. The systems that are out of context are systems that are not

considered to affect the new system.

3.3.3 Requirements Abstraction Model

When requirements have been collected from the different sources, there is a risk that there will be many requirements that cannot be handled if it is not performed in a structured way. When requirements are elicited, they come in different levels of abstraction and state of refinement. Requirements Abstraction Model (RAM) is a method used to handle incoming requirements by sorting requirements into different levels of abstraction. Using the method, the requirements are placed in four different levels of abstraction. The first level is the “product level”, where requirements placed here are considered most abstract in order to be directly compared with product strategies and indirectly with organizational strategies. Requirements placed at this level can help managers to include, exclude or prioritize requirements. The second level of abstraction is the “feature level”, where requirements placed here can be seen as the characteristics of the new system. The third level of abstraction is the "function level", where requirements placed here can be seen as concrete enough to explain what a system or a user should be able to do. It is also at this level that the requirements can be tested. The fourth

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and final level is the “component level”, requirements placed at this level are in a very detailed form and most concrete. [31] The four levels of abstractions are presented in the list below:

1. Product level (Goal)

2. Feature level (Characteristics) 3. Function level (Functions/Actions) 4. Component level (Details)

When requirements are obtained, they are placed and specified at an appropriate level of abstraction. Depending on the level at which the requirements are placed, it is appropriate to abstracting low-level requirements up to product level and vice versa. This is done by creating requirements both above and below and linking them to the original requirement. In some cases, requirements already exist at other levels of abstraction, then it is about matching the requirements with each other. The purpose is to be able to make decisions and at the highest abstraction level, but also as input to projects for realization from the lower abstraction levels. [31]

3.3.4 Multi-Dimensional Classification

Another way to sort requirements is to divide them into different classes, where requirements are classified. Examples of classes may be system, user interface, database, communication and security. By classifying the requirements into the different classes, similarities and contradictions can be more easily found. This facilitates the merger and / or elimination of requirements. A requirement can be classified into more than one class, of which the name Multi-Dimensional. Classification of requirements also facilitates identification of missed requirements. For example, if a class has been defined and no requirements are classified in that class, there is a risk that important requirements have been left out. Another advantage is if a requirement in a class changes, it is easier to consider other requirements that can be affected in the same class. [30]

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4 Method

This chapter describes the method that was used with the purpose to reach the aim of this study and to answer the presented research questions. The chosen methodology applied in this thesis

is a case study combined with aspects from Requirements Engineering.It includes a pre-study,

identification of stakeholders and system context, elicitation and analysis of requirements.

4.1 Motivation of Research Strategy

When deciding what approach to choose and what research methodology that is applicable for this study it is recommended to look at the formulation and purpose of the research questions. The formulated research questions in the study are mainly designed with “what”, but are more of the “exploratory”-type. To answer research questions formulated in this way a case-study approach is suitable. [32] The aim is find potential challenges for Saab Aeronautics when reusing their current data for creating Augmented Reality Work Instructions, which further indicate the exploratory nature of this study.

Case study methodology is a study in real circumstances that is applicable in most scientific studies. The purpose of conducting a case study is to study a small part of a large process and that small part is used to describe the reality. The advantage of this methodology is that there is no need to deep dive into the big description, it is enough with a limited scope to be able to give the reader an idea of how something is represented in reality. The difficulty when working with one case is that it cannot fully represent the reality and therefore the conclusions should be carefully drawn. [32]

The methodology is suggested as suitable for software engineering and systems engineering, research as it is a flexible type with significant amount of iterations over the steps. To succeed with a case study, good planning is needed. It is about planning all the steps in a case study, for example which method is to be used in data collection or which people that are to be interviewed. [33]

4.2 Case Study Structure

There are commonly five major steps to walk through when conducting a case study. A suggested work progress structure is as followed [33]:

1. Case study design

2. Preparation for data collection 3. Collecting evidence

4. Analysis of collected data 5. Reporting

In order to reach the aim of this study, the research questions were defined. The formulated research question allowed the study to be planned in order to cover all relevant areas. To answer the research questions, a suitable method was needed. Requirements Engineering was found as a method that would fit this project, where the goal, context, stakeholders and requirements of a system needs to be defined [27]. Requirements Engineering allows the problem to be regarded from a systems perspective. Where the requirements will be used to define the Augmented Reality Work Instruction and to answer RQ(1). These requirements needs to go in line with the system context, which in this case will be the possibility to reuse the current data to create the new instructions in AR and will answer RQ(2).

Requirements Engineering is considered as an iterative process in order to ensure that

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iteration over the steps and that the data collection and analysis can be carried out incrementally [33]. This strengthens that Requirements Engineering is suitably to apply in a case study design. Based on this, a plan for the study was made in order to build a method that combines the case study structure with Requirements Engineering tailored to reach the aim of the study. The process flow of this study is presented in Figure 3.

The list below shows the original case study phases to the left and the adapted phases used in this project to the right, based on Requirements Engineering:

 Case Study design - Pre-study

 Preparation for data collection - Identify Sources of requirements

 Collecting evidence - Requirements Elicitation

 Analysis of collected data - Analysis of Requirements

 Reporting - Discussion and Conclusion

Figure 3. Overview of the study process flow, each grey box represents a phase and included activities in that phase. The yellow box represents the input that is used in the analysis of Pre-study

The first step in this study was to conduct a thorough pre-study. The purpose of the pre-study was to delimit the project and to formulate the research questions and to define the aim.

An overview literature study was conducted to find out how far industrial use of Augmented Reality has come today in order to find out where the focus of this thesis should be placed. Also, to get a fundamental understanding of the technology, what the difference is of transferring information to the shop-floor worker with Augmented Reality versus the technology they use today.

The system’s goal was defined in this step by discussing the purpose of the new system with the supervisor. The system’s goal was used during the whole project as a guideline to ensure that the elicited requirements were in line with the overall purpose. The system’s goal in presented in section 6.1.

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4.3 Identify Sources of Requirements

Commonly, when performing case-studies there are six main types of data collection methods: documentation, archival records, interviews, direct observation, participant-observation and physical artefacts. However, there are also other methods that can be used to collect evidence for the case-study. The different sources are argued to be complementary to each other and it is recommended to use as many different sources as possible. [32] The requirements needed to be based on both the needs of stakeholders and on what data from the current system that can be reused for the creation of the new instructions.

4.3.1 Selecting Interviewees – Stakeholder Analysis

As the case-study is of the qualitative nature it is recommended select the interviewees to cover a broad area instead of trying to replicate similarities [33]. The interviewees were selected so their knowledge would cover all the areas that were relevant for this study. A method that was used to find internal interviewees was a stakeholder analysis that was conducted together with the thesis supervisor at the company. The purpose of conducting a stakeholder analysis is to find how the identified stakeholders is affected or can affect the result of the study [34]. The stakeholder analysis was based on two aspects, if they could provide knowledge about the current system or if they could provide requirements for the new system. The stakeholder identification was also based on whether they are available at the company. An open dialogue with the supervisor took place to list all possible relevant stakeholders. During the interview phase, continuous addition were added to the list of potential interviewees. The result from the stakeholder analysis was the selected interviewees presented in 4.5.1.

4.4 Requirements gathering and elicitation

The requirements elicitation process was conducted in order to gather raw data from stakeholders and to get an understanding of how the current system will affect the new system. It was carried out with four different techniques described more thoroughly in the following section.

4.4.1 Document Analysis

A search was conducted in Saabs internal standard database in order to find standards of how the work when creating work instructions at Aeronautics should be carried out. Documents should in general be regarded with care when it comes to a source of evidence, and a recommendation is to mainly use them for the purpose of comparing the evidence with other sources of evidence. The validity of the document needs to be verified and evaluated in order to use them as a source of data. [32] At Saab, the internal standards are continuously updated and are not valid anymore when they are printed from the database. The document analysis technique was frequently used during this study, as it served as a way to formulate further questions from.

4.4.2 Internal Learning Courses

The company provides internal learning courses to employees that works with the MBD-system and a more detailed course of the production planning that is carried out in the software DELMIA. The purpose of taking these courses was to get an introduction to the system. The courses were attended via Saabs internal learning platform and was carried through the internet. It was possible to repeat the courses as many times as required.

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4.4.3 Literature search

A literature study was conducted to gather knowledge about work instructions and Augmented Reality. The main findings of the literature study are presented in section 3Fel! Hittar inte referenskälla.. The literature search was mainly carried out in Google Scholar, Linköping University Library and the main search words were:

 Augmented Reality

 Augmented Reality Work Instructions  Requirements Engineering

 MBD Product Definition

4.5 Interview Methodology

When it comes to case-studies, one of the most important sources of evidence is gathered through interviews [32]. In interview-based data collection, the researcher are asking a set of questions on relevant topics in the case-study to a set of interviewees. The questions can either be open- or closed-ended. Open questions allow a more broad range of answers and allows the interviewee to bring up what is considered important. Closed questions is often limited to have a pre-defined set of answers to choose from. [33]

“Semi-structured” interviews was selected as the main interview type for this study, which is a structured but open type of interview. It focuses on preparing questions in advance before the interview, but also allows flexibility to ask follow up questions on topics that were brought up and considered interesting during the interview. The prepared questions were adapted for the purpose of that interview, this was done in order to get the most relevant knowledge from that interview.

4.5.1 Internal Interviews

In total 12 stakeholders were interviewed in this study. The interviewees are presented in the list below that describes their knowledge areas and the purpose of how the interview.

System architect (1) – An interview was conducted with a system architect in order gain knowledge about the system integration and data flow at Saab Aeronautics. The system architect possess knowledge of the file formats used and how data is structured.

System developer (1) – A system developer is working with maintenance and development of existing systems at Saab Aeronautics. The interview was focused on creating an understanding of how the DELMIA software works on a more system level, for example how the functions in the software are built up.

Shop floor workers (4) - The shop floor worker is considered as the end user of the work instructions at Saab Aeronautics. Three of the interviewees worked with the final assembly of Gripen E and one on them with partial assembly of the wings. The purpose of these interviews was to gather knowledge how the work instructions are used today and how they can be improved. They had limited knowledge about Augmented Reality and how it can be used in industrial needs. The interviews was focused on finding requirements that was not directly linked to Augmented Reality but that could be used together with other gathered data.

Process planners (3) - The process planner is responsible for planning the assembly work for Gripen E. They create the work instruction that is viewed by the shop floor worker in the

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application Catia Composer. The interviews were mainly focused on gaining information of how the instruction are created, which functions that are used, which data they need and how they work in DELMIA.

Project leader of GAIS2 (1) - An interview was held with a project leader that has been involved in previous work regarding Saabs MBD-methodology and work instructions. The interview was mainly focused on the previous work and on research regarding Augmented Reality and how it can improve the cognitive learning of the user.

Method developer (1) - Responsible for method development at Saab Aeronautics. The purpose of the interview was to gather future visions that the company has with Augmented Reality Work Instructions, what new opportunities they see with the new technology.

Design engineer (1) - The design engineer is responsible for the product design in the software CATIA. It is the designers who create the 3D models that are later used in DELMIA. The purpose of the interview was to gain knowledge of how 3D models are designed and what information that is included.

4.6 Analysis of Requirements

When the requirements elicitation were conducted it was necessary to perform an analysis of the gathered information. This was done in order to screen out irrelevant requirements that contradict each other or did not align with the system goal. The purpose of the analysis was to identify, structure and categorize the most important requirements. The analysis step was based on guidelines for requirement analysis [30].

The first step in the analysis process was to transcribe all the conducted interviews. The transcription was used to identify segments of either future wishes, statements of how Augmented Reality can be utilized, key functions the shop floor worker used in the current work instructions and challenges that can occur with the new technology.

One aspect that had to be considered was that many requirements were based on the current work instructions and had to be translated to Augmented Reality, in order to do this guidelines of Augmented Reality Work Instructions was used presented in section 3.2.1. The other aspect was to compare the need of the stakeholders with the current system. This was based on the situational analysis presented in section 5, which describes how data was created, structured and available to be reused.

The analysis required in some cases that more data had to be collected in terms of more stakeholder interview or gaining more knowledge about how the system context affects the requirements. This resulted in that more interviews were conducted incrementally.

A summary of all requirements were written down in a document. The requirements were compared to a quality criteria list presented in section 3.3.1. This was done to ensure that the requirements were correctly formulated and could be understood by the stakeholders.

The next step was to classify the written down requirements. This was done based on the Multi-Dimensional Approach [30]. Each of the requirements were listed in one of the classes and allowed the requirements to be analysed in terms of finding similarities and if some of them contradicted each other.

The elicited requirements were in different levels of abstraction. For example one requirement was stating that the augmented reality work instruction should lead to reduced cognitive load for the shop floor worker and another stated that the augmented reality work instruction should be divided into different WI-steps. In order to structure the in terms of level

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the RAM methodology the focus was to identify the function level requirements as that level provided the requirements to be concrete enough to define what the functionality of the Augmented Reality Work Instruction should consist of. The higher levels in the RAM framework was used to verify that the requirements on the function level did align with overall organizational strategies and possible features of the system. As the main requirements that were focused on described functionality in some sense they had to be prioritized in terms of necessity [27]. Two levels of that described the necessity was used based: “must” and “should”. Must means that the requirement must be fulfilled and should does not have to be fulfilled but would contribute to a better solution if they are considered.

The finished analysis of requirements are presented in a RAM framework, divided into the stated classifications with the level of necessity highlighted, presented in section 6.7.

4.6.1 Validation of Requirements

To ensure that the requirements are valid and match what the company desires from the AR-instruction a validation of the listed requirements was be carried out. The validation consisted of continuous meetings with the supervisor from the company, where the requirements were discussed and decided if they are relevant to be proceed with.

4.7 Triangulation

Triangulation is a strategy that can be used to strengthen the quality of a case study as it is a qualitative based type research. As described in [33] there are four different aspects to consider when applying the triangulation strategy to the research.

 Data Triangulation: To use several sources of data or collecting the same data on different occasions.

 Observer Triangulation: To use more than one observer when collecting and analysing the collected data.

 Methodical Triangulation: To combine different types of data collecting methods.  Theory Triangulation: to use alternative theories or viewpoints.

4.8 Research Ethics

This study contains and results are based on interviews from employees at Saab Aeronautics. To ensure that it is not possible to track a statement about requirements or possible challenges for Saab back to a single individual only the role of the interviewees has are presented. The collected data in terms of interview recordings and transcribed interviews are only accessible by the authors of the study. The authors ensures that all transcriptions and recordings will be deleted at the end of this thesis.

Another aspect that the authors are aware of is that the work is carried out in the military aircraft industry. This study can be seen as an early part of the development of work instructions in Augmented Reality for assembly of the military aircraft Gripen E. What the authors believe is that the result of this study has no direct effect on the society, neither positive nor negative, because it is an early phase in a development project. In the long run, the development project could contribute to increased resource efficiency and thus reduce the negative environmental impact. By transferring to new "modern" technology for visualizing work instructions, this could in the future help to attract younger people to this field of work.

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5 Situation Analysis

In this chapter the main findings from the situation analysis will be presented. These finding are based on conducted internal interviews, internal learning courses and document analysis of internal standards explaining work methodology at Saab Aeronautics. This chapter aims to describe the current system used at Saab Aeronautics to create work instructions for installation of wire harnesses. First an explanation of wire harnesses will be given to explain aspects that are important to consider in assembly. Then the Model Based Definition methodology will be described and how it is applied at Saab Aeronautics. Then the process of creating work instructions from part design to the final work instruction is explained, touching on important findings where new data is created.

5.1 Wire Harness

In the assembly of Gripen E, there are two main assembly sections, Airframe/Structural assembly and Final assembly. In the final assembly the main parts, for example the wings and the centre fuselage has already been assembled. Here the final assembly is carried out where devices, wire harnesses, pipes and other components are assembled to the airframe of the aircraft. It is the assembly of wire harnesses that will be the main focus in this thesis and is where the case study will be carried out.

The purpose of wire harnesses is to connect different devices that are installed in the aircraft which needs to communicate with each other. A wire harness consists of several cables and connectors. The connectors are placed in the ends of the wire harness and are used to connect with devices. If several wire harnesses are placed together, it is called wire harness bundle. There are different types of wire harnesses, where the different types are defined as classes, are suitable for different purposes.

In the final assembly station, work instructions are displayed on stationary computers. The work instruction describes what to perform in an operation for the shop floor workers. For installation of wire harnesses, work instructions are used to describe how wire harness should be positioned in the aircraft and which wire harness that are included.

There are tight spaces when wire harnesses is to be installed, which sometimes makes it difficult for the shop floor workers to install according to the work instruction.

There are central clamping points (CCP) in the aircraft to facilitate the shop floor workers' work when installing wire harnesses. Central clamping points consist of tape markings, both in the aircraft and around the harnesses. The purpose is to match the markings with each other to ensure that the wire harnesses are positioned correctly in the aircraft. A fixed positioned clamp, which holds the wire harnesses together, have a CCP marking in the aircraft. It is up to the shop floor workers to ensure that the wire harness with the corresponding CCP marking coincides with the fixed positioned clamp at the exact position. These central clamping points are also marked in a work instruction.

In order for wire harnesses to be in place and sometimes together with other wire harnesses, wire harnesses are lashed with a specific lashing yarn. In a work instruction it is not described where and how the lashing should be performed. The different wire harnesses classes use specific types of lashing yarn. That is also how different wire harnesses classes can be distinguished in reality, with help of the type of lashing yarn. There are internal standards for how lashing of wire harnesses should be performed and are referred in the first WI-step. Figure 4 shows an example of how the shop floor workers can use work instructions in the final assembly station.

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Figure 4. This is an example of how the work instructions can be displayed for the shop floor workers at the shop floor. In the picture two work instructions are opened with different tasks, where each

work instruction is dedicated for one shop floor worker. Retrieved from: [https://mediaportal.saabgroup.com/#/items/23416]Copyright Saab AB, Harri Koskinen

5.2 Model Based Definition at Saab Aeronautics

2D-drawings are commonly the traditional way industries uses to transfer design to the shop floor workers. The purpose of these drawings are to include and carry the product definition. Nowadays, it is common to use Computer Aided Design (CAD) tools and 2D-drawing are transitioned to drawings. Model Based Definition (MBD) is a strategy involving 3D-models as the primary information carrier. The 3D-model contains the product definition and its geometry-data. The product definition contains the data necessary for design development, production and maintenance of the product. Some of the primary advantages of using MBD-methodology is shorter lead times, improved quality and reduced costs. [35]

Today, Saab Aeronautics have implemented MBD-methodology for manufacturing, development and maintenance of Gripen E. The product definition is stored as a 3D-model of the actual product. This 3D-model is entitled as the product definition at Saab Aeronautics and it is used during the full life-cycle of the product from design to maintenance. The product definition contains all the specifications needed, which includes tolerances, surface treatment requirements and additional information needed to manufacture Gripen E. With this methodology it is no longer needed to store and update 2D-drawings. Saab utilizes the MBD-methodology to effectively meet the challenges in the aeronautical industry.

The 3D-master models are shared between departments through integrated systems solutions. The models are shared downstream in the process flow and are used for part design, assembly design, process planning and to create 3D-based work instructions for the shop floor workers. Figure 5 below illustrates how the methodology is applied for the different departments in the company for manufacturing of Gripen E.

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Figure 5. A simplified picture of how the MBD-methodology is applied at Saab aeronautics for manufacturing of Gripen E. It shows which departments that are linked to and uses the 3D-model

product definition. Retrieved from: [Internal material], Copyright Saab AB.

The product definition is created and maintained by the design engineer in the design phase. The models are created in CATIA and are saved in their internal Product Data Management-system. When the product definition has been released, it is the same models that the process planners are using to create assembly work instructions. The work instructions are created in the software DELMIA, which are integrated with the MBD-data flow. When the work instructions are released, they are used by the shop floor workers in the production. The shop floor worker has access to the work instructions through the Enterprise Resource Planning (ERP) database.

5.3 Product Design

In order to initiate the process planning phase in DELMIA at Saab Aeronautics, 3D models are needed. CATIA is a Computer Aided Design (CAD) software that the design engineers at Saab Aeronautics uses for the design of parts. This design will serve as technical documentation of the part, stored as a 3D model. When designing, the product definition is used as a reference to position and decide the shape of the part to put it in a relation to the rest of the aircraft. The 3D models are described in the actual size of the parts. All parts that are designed for Gripen E are related to one coordinate system in the aircraft, which is placed in front of the aircraft. The 3D models included in the aircraft have their own coordinate system. All 3D models have a displacement in x,y,z and three angles in relation to the aircraft’s coordinate system, to define the position of each 3D model.

The design engineers handles both the design of the wire harness itself and the associated mechanical parts. In the design phase, 3D models for both detail manufacturing and for assembly is created. The detail manufacturing builds the wire harnesses and the final assembly installs it in the aircraft. 95% of all of the wire harnesses that are installed in the final assembly are built in-house at the company. The components that are not built in-house are usually

Maintenance Simulation Suppliers Process planning Maintenance Design Production Part drawing Virtual verification Product definition in 3D

Work instruction authoring

Work instruction

Technical information Maintenance instruction authoring

3D model / Product definition

Prerequisites for Automatically Creating Work Instructions in Augmented Reality for Assembly of Gripen E : a case study at Saab Aeronautics