Reclined seating positions for level 4 HAD vehicles
A comfort and safety approach
Andreas Hagberg Sandra Jodlovsky
Industrial Design Engineering, master's level 2017
Luleå University of Technology
Department of Business Administration, Technology and Social Sciences
Reclined seating positions for level 4 HAD vehicles
A comfort and safety approach
Andreas Hagberg Sandra Jodlovsky 2017
SUPERVISOR: Therese Öhrling & Katarina Bohman REVIEWER: Jörgen Normark
EXAMINER: Lena Abrahamsson/Åsa Wikberg Nilsson
CIVILINGENJÖR I TEKNISK DESIGN MSc in Industrial Design Engineering Luleå University of Technology
Reclined seating positions for level 4 HAD vehicles - a comfort and safety approach
© Andreas Hagberg & Sandra Jodlovsky Published and distributed by
Luleå University of Technology SE-971 87 Luleå, Sweden
Telephone: + 46 (0) 920 49 00 00 Printed in Luleå Sweden by
Luleå University of Technology Reproservice Luleå, 2017
Acknowledgement
We would like to warmly thank all people that have supported us during our master thesis project. First of all, we would to thank our supervisors Katarina Bohman at Autoliv
Development AB and Therese Öhrling at Luleå University of Technology (LTU) for all the support and guidance you have given us.
The user needs and other data wouldn’t have been obtained if it weren’t for the people that participated in our studies, so we would like to thank you all who participated. We would also like to thank the students at LTU and the employees at Autoliv who helped us to generate ideas.
Some employees at Autoliv also helped us to evaluate our concepts, we are grateful for your input and would like to thank you.
Thank you Annika Larsson at Autoliv for contributing with your expertise in Human Factors when we formulated the questions that we asked in interviews and in the survey. We would like to thank Yogen Patel at Autoliv for being available when we had questions regarding the project.
The people that reviewed the draft of this thesis report contributed with valuable comments that made the report better. So thank you Åsa Wikberg-Nilsson, Jörgen Normark, Allan Said and Jenny Nilsson at LTU for that.
Last but not least, we thank Mikael Enänger, Johan Holmsten and Daniel Nylén at Autoliv for building a car rig and supporting us when we conducted our clinics in Vårgårda.
Gothenburg 11th of June, 2017
Sandra Jodlovsky Andreas Hagberg
Abstract
KEYWORDS: Submarining, HAD, Level 4, Reclined seat back, Restraint system, Clinic, Automation.
Occupants have already in today’s cars the opportunity to choose various reclined seating positions. As highly automated driving (HAD) vehicles are introduced on the market, the possibility to sit in reclined positions will increase. The car manufacturers will most likely be responsible for ensuring crash safety for new seating positions. Therefore, the restraint system has to be developed to make these seating positions safe.
The objective of this master thesis is to make reclined seating positions safer and comfortable in level 4 HAD vehicles, with a focus on the lap belt geometry and submarining. The aim is to investigate how people want to sit in relaxed positions in level 4 HAD vehicles. With that information provided, develop a restraint system that meets the user and safety requirements with a focus on submarining. Submarining is an unwanted phenomenon that can occur during frontal collisions where the occupant slides under the lap belt (Hermitte & Labrousse, 2012).
The solution should be delivered as sketches and renderings. The work is performed in cooperation with Autoliv Development AB. The project has been conducted by using a user- centered-design process. The methods have been chosen to generate user-centered results.
Autoliv, as the constituent, has been involved in the project through all of the project’s phases, which has been benefiting for the progress.
The result shows that in today’s cars, 48% of the passengers preferred to sit in a relaxed position where the seat back was reclined over 30 degrees. 56% of the passengers chose a seat back angle over 30 degrees when they wished to sleep. In the level 4 HAD vehicles, people wanted to recline the seat back more. 80% chose a seat back angle over 30 degrees when relaxing, in both the drive’s and passenger seat. 100% of the passengers chose a seat back angle over 30 degrees when they wished to sleep.
The result indicates that the lap belt geometry deteriorated when the seat back reached an angle over 30 degrees. This means that the majority would, in their relaxed position, have a lap belt geometry that could increase the risk for submarining. The pelvis rotation that comes with reclined positions is one of the reasons that cause submarining (Couturier, Faure, Satué
& Huguet, 2007). SafeX is a concept of a restraint system, developed as a part of this thesis. It provides a safer way for the occupants to sit in their most comfortable seating positions, with the pelvis rotation in consideration.
This project provides Autoliv with valuable data for further investigation and development of restraint systems.
Sammanfattning
NYCKELORD: Underglidning, HAD, Nivå 4, Bakåtlutat ryggstöd, Fastspänningsanordning, Klinik, Automation.
Redan i dagens bilar har passagerare möjligheten att sitta i olika tillbakalutade sittpositioner.
Samtidigt som högautomatiserade (HAD) bilar är introducerade på marknaden, ökar möjligheten till att sitta i tillbakalutade positioner. Biltillverkarna kommer förmodligen ha ansvaret för att göra nya sittpositioner säkra i samband med krock. På så sätt behöver säkerhetsanordningen utvecklas för att göra dessa sittpositioner säkra.
Syftet med detta examensarbete är att göra tillbakalutade positioner säkrare och komfortabla i nivå 4, HAD-bilar, med fokus på höftbältesgeometrin och underglidning. Syftet är att undersöka hur folk vill sitta avslappnat i nivå 4, HAD-bilar. Med den informationen tillhandahållen skall en säkerhetsanordning utvecklas som möter användar- och säkerhetskrav, med fokus på underglidning. Underglidning är ett oönskat fenomen som kan uppstå vid frontalkrockar där den åkande glider under höftbältet (Hermitte & Labrousse, 2012).
Lösningen ska levereras i form av skisser och renderingar. Projektet utförs i samarbete med Autoliv Develoment AB. Projektet har utförts genom att använda en användarcentrerad designprocess. Metoderna har valts för att generera användar-centrerade resultat. Autoliv som uppdragsgivare har varit involverade genom alla projektets faser, vilket har varit fördelaktigt för framåtskridandet.
Resultatet visar att i dagens bilar föredrog 48% av passagerarna att sitta i en avslappnad position där ryggstödet var lutat över 30 grader. 56% av passagerarna valde en ryggstödsvinkel över 30 grader när de önskade att sova. I nivå 4 HAD-bilarna ville folk vinkla ryggstödet mer. 80% valde en ryggstödsvinkel över 30 grader när de ville slappna av, i både förar-och passagerarsätet.
100% av passagerarna valde en ryggstödsvinkel över 30 grader när de önskade att sova.
Resultatet indikerar på att höftbältesgeometrin försämrades när ryggstödet nådde en vinkel över 30 grader. Detta betyder att majoriteten, i deras avslappnade position, skulle haft en höftbältesgeometri som skulle kunna öka risken för underglidning. Höftrotationen som uppstår i samband med tillbakalutade positioner är en av anledningarna som orsakar underglidning (Couturier, Faure, Satué & Huguet, 2007). SafeX är ett koncept av en fastspänningsannordning, utvecklad som en del av detta examensarbete. Det bidrar med ett säkrare sätt för passageraren att sitta i sin mest komfortabla sittposition, med hänsyn till höftrotationen.
Detta projekt tillhandahåller Autoliv med värdefull data för fortsatta undersökningar och utveckling av säkerhetsanordningar.
Content
1 INTRODUCTION
1.1 Background 10
1.2 Stakeholders 11
1.3 Objective and aim 11
1.4 Project scope 12
1.5 Thesis outline 12
2 CONTEXT
2.1 Autonomous driving 14
2.2 History of the seat belt 15
2.3 Current state 16
2.4 Benchmarking 17
3 THEORETICAL FRAMEWORK
3.1 Industrial design engineering 21
3.2 Submarining 21
3.3 Ergonomics and anthropometry 25 3.4 Anthropometric aspects of seat design 26
3.5 Comfort 26
4 METHOD AND IMPLEMENTATION
4.1 Process 28
4.2 Project planning 28
4.3 Context immersion 29
4.4 Requirement specification 45
4.5 Idea generation 46
4.6 Concept development 49
4.7 Detailed design 50
5 RESULTS
5.1 Context immersion 52
5.2 Requirement specification 82
5.3 Idea generation 83
5.4 Concept development 84
5.5 Detailed design 86
6 DISCUSSION
6.1 Result of the context immersion 92
6.2 Final concept 93
6.3 Relevance 94
6.4 Reflection 95
6.5 Limitations 95
6.6 Recommendations 95
6.7 Conclusion 96
List of appendices
Appendix 1. Gantt- chart
Appendix 2. Formulary Focus group Appendix 3. Volvo Interview
Appendix 4. Formulary Clinic 1
Appendix 5. Result Requests for comfortable seating positions in today´s cars. Clinic 1 Appendix 6. Rig specifications
Appendix 7. Formulary Clinic 2 Appendix 8. Formulary Clinic 3 Appendix 9. Pelvis rotation Appendix 10. Web survey
List of Figures
Figure 1. Introduction. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 2. Autonomous driving. 2025. (n.d.) Iconic image of automated driving. Available from https://www.2025ad.com/latest/
milestones-the-ad-timeline/?type=0%252525 252525253Ftype%252525252525253D7777 Figure 3. Autonomous driving. SAE Interntional. (2014). J3016. Available from https://www.sae.org/misc/pdfs/automated_
driving.pdf
Figure 4. Benchmarking. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 5. Submarining. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 6. Submarining. Reed, M. (2013).
Effects of Driver Characteristics on Seat Belt Fit.
Figure 7. Submarining. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 8. Submarining. BMW VISION NEXT 100 Design sketches, ID: P90212366, https://
www.press.bmwgroup.com/global/photo/
detail/P90212366/bmw-vision-next-100- design-sketches-03/2016. Mercedes-Benz F 015 Luxury in Motion: The variable seating system, with four rotating lounge chairs that allow a face-to-face seat configuration, ID: 14C1450_077, http://media.daimler.
com/marsMediaSite/en/instance/ko/Start.
xhtml?oid=4836258. Concept 26, ID: 169543, https://www.media.volvocars.com/global/en- gb/media/photos/list.
Figure 9. Ergonomics and anthropometry.
Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 10. Process. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 11. Clinic 1. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 12. Clinic 1. Photo: Andreas Hagberg Figure 13. Clinic 1. Photo: Andreas Hagberg Figure 14. Clinic 1. Photo: Andreas Hagberg Figure 15. Clinic 2. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 16. Clinic 2. Photo: Andreas Hagberg Figure 17. Clinic 2. Photo: Andreas Hagberg Figure 18. Clinic 2. Photo: Sandra Jodlovsky Figure 19. Clinic 2. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 20. Clinic 2. Keil, D. (2012). How to check your pelvis.
Figure 21. Clinic 2. Photo: Andreas Hagberg Figure 22. Clinic 2. Photo: Andreas Hagberg Figure 23. Clinic 2. Photo: Andreas Hagberg Figure 24. Clinic 2. Photo: Andreas Hagberg Figure 25. Clinic 2. Photo: Andreas Hagberg Figure 26. Clinic 3. Photo: Andreas Hagberg Figure 27. Clinic 3. Photo: Andreas Hagberg Figure 28. Clinic 3. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 29. Clinic 3. Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 30. Clinic 2. Photo: Andreas Hagberg Figure 31. Idea generation. Photo: Andreas Hagberg
Figure 32. Idea generation. Photo: Andreas Hagberg
Figure 33. Idea generation. Photo: Andreas Hagberg
Figure 34. Idea generation. Photo: Andreas Hagberg
Figure 35. Idea generation. Photo: Andreas Hagberg
Figure 36. Idea generation. Photo: Andreas Hagberg
Figure 37. Concept development. Photo:
Andreas Hagberg
Figure 38. Detailed design. Photo: Andreas Hagberg
Figure 39. Context immersion. Illustration:
Andreas Hagberg & Sandra Jodlovsky
Figure 40. Context immersion. Illustration:
Andreas Hagberg & Sandra Jodlovsky
Figure 53. Context immersion. Illustration:
Andreas Hagberg & Sandra Jodlovsky
Figure 60. Context immersion. Illustration:
Andreas Hagberg & Sandra Jodlovsky
Figure 61. Context immersion. Illustration:
Andreas Hagberg & Sandra Jodlovsky
Figure 112. Context immersion. Illustration:
Andreas Hagberg & Sandra Jodlovsky
Figure 113. Requirement specification.
Illustration: Andreas Hagberg & Sandra Jodlovsky
Figure 114. Idea generation. Illustration:
Andreas Hagberg & Sandra Jodlovsky
INTRODUCTION 1
1 Introduction
This is a master thesis in Industrial design engineering, at Luleå University of Technology. The constituent of the project is Autoliv Development AB in Vårgårda, Sweden, where the project is mostly performed. It is a development project where the aim is to develop a restraint system that meet users’ comfort requirements and make their seating positions safer, with focus on the lap belt geometry and submarining.
In the cars of today, the occupants have the opportunity to choose various seating positions where the seat back is reclined. These reclined seating positions can increase the risk of injury during frontal collisions due to the risk of submarining (Thorbole, 2015). According to Royce (2011), a reclined seating position is one where the seat back is reclined more than 30 degrees from the vertical.
Submarining is a phenomenon where the occupant slides under the lap belt in a frontal collision (Hermitte & Labrousse, 2012). The lap belt is then unable to restrain the occupant in the designed manner as it passes above the bony pelvis (Eggers et al., 2016). The occupant’s abdomen is then exposed to the force of the lap belt, see Figure 1, which can cause the abdomen and lumbar spine to be seriously injured (Kim, Kim, Kim and Lee, 2015). The injuries caused from submarining can in the worst cases be fatal (Hermitte & Labrousse, 2012).
Based on semi-realistic concepts from car manufacturers, highly automated driving (HAD) vehicles might enable the possibility for reclined positions. The car manufactures will most likely be responsible for the actions that the car makes during autonomous driving mode. They may therefore have to prove the safety of the offered seating positions that are available in autonomous driving mode.
Volvo’s CEO Håkan Samuelsson (2015) says: “ Volvo will accept liability whenever one of our cars is in autonomous mode. Mercedes and Google have made similar claims (Elmer, 2015).
They would effectively be responsible for injuries that occur in autonomous mode. Injuries that could be more severe if the seat is reclined.
1.1 BACKGROUND
There is no current regulation or rating evaluating reclined seating positions, even though reclined seats can cause submarining. It is up to the car manufacturers themselves to evaluate the car. People might recline their seat, not aware of the restrictions of their specific car.
Automotive experts from around the world have developed the SAE standard J3016TM, which is a classification of automation levels in on-road motor vehicles. Autonomous vehicles that occupy the roads today are between level 2 and 3, conditional automation. On this level, the driver is expected to respond appropriately to a request to intervene. The industry is now striving to reach level 4, high automation, where the driver does not have to respond appropriately to a request to intervene (SAE International, 2016).
As highly automated driving (HAD) vehicles are introduced on the market, it is necessary to Seat belt Force
Femur Force
Seat Force
Legs
Upper body
FIGURE 1. SEAT BELT FORCE.
FIGURE 1. SEAT BELT FORCE.
develop restraint systems to protect the driver in new, challenging positions. The driver will not be dedicated to drive the car, and might therefore start to behave similar to a front seat passenger. The driver might be occupied in activities such as sleeping, interacting with other occupants, watching their smartphone, reading, etc.
There is a need to understand how people sit in relaxed positions in the front passenger seat today, and furthermore how people want to sit in reclined positions if there are no restrictions from the car manufacturers. How can comfort needs be combined with the safety features needed, in order to protect the occupant in case of a front collision?
1.2 STAKEHOLDERS
The constituent and stakeholders who are involved and affected by the project are described below.
1.2.1 Autoliv Development AB
The constituent of the project is Autoliv Development AB. The company was founded in 1953 by Lennart Lindblad in Vårgårda, Sweden. Today, Autoliv is the largest automotive safety supplier in the world and distributes to all the leading car manufacturers. According to Autoliv, their focus is on one very important issue, saving lives. They develop, manufacture and market protective systems such as seat belts, airbags, steering wheels, passive safety electronics and active safety systems, among others. Their innovative products save 30 000 lives a year and prevent ten times as many injuries (Autoliv Development AB, n.d.).
Autoliv develops safety systems for HAD vehicles. In these vehicles, there will be opportunities for the driver to sit in various positions. New challenges emerge with these positions concerning the safety for the occupants, which are in interest for Autoliv to investigate and solve. In-house stakeholders are the producers of the products or systems developed by Autoliv.
1.2.2 Car manufacturers
Autoliv is a subcontractor to approximately one hundred car manufacturers all over the world (Lundgren, 2014). These car manufacturers are therefore affected by the restraint systems that Autoliv develops.
1.2.3 Front seat occupants
According to Jorlöv (2016), it is shown that front seat occupants want to sit in relaxed positions during the drive in HAD vehicles. In order to sit relaxed, they might want to recline their seat and are therefore affected by the risks that comes with these positions.
1.3 OBJECTIVE AND AIM
The objective of this master thesis is to make reclined seating positions safer and comfortable in level 4 HAD vehicles, with focus on the lap belt geometry and submarining. The aim is therefore to investigate reclined positions and develop a restraint system that counteracts submarining and meets the users´ comfort needs in relaxed positions. In order to achieve the objective, the following research questions will be investigated:
• How can a safe lap belt geometry be defined today?
• How do people (as passengers) sit in relaxed positions today and how does that affect the lap belt geometry?
• How do people want to recline their seat in a level 4 HAD vehicle – when relaxing and when sleeping?
• How can comfort and safety be combined, with focus on the lap belt’s interaction with the pelvis?
The developed solution is expected to contribute to the HAD vehicle’s restraint system that Autoliv will deliver to car manufacturers. The car manufacturers will be able to equip their HAD vehicles with restraint systems that meet safety requirements. The restraint system will then provide safety and comfort to the front seat occupants in HAD vehicles.
The objective will be accomplished through literature and user studies which will contribute with immersed knowledge about submarining and user needs. The result will be presented through sketches and rendered pictures.
1.4 PROJECT SCOPE
The estimated time for the project is 40 hours a week per person during 20 weeks. We are two students who will work with the project, which corresponds to a total of 1600 hours.
The following list shows the delimitations of the project:
• Rear seats will not be included in the study.
• People under 18 years will not be included. Including children is too extensive within this time frame since it adds a broader range of anthropometric data needed to be taken into account.
• Exact details and dimensions will not be determined in the final concept.
1.5 THESIS OUTLINE
Chapter 1 comprises an introduction of the master thesis and Chapter 2 provides the reader with the context of the work. Chapter 3 presents the theoretical framework that the thesis is based on. Chapter 4 describes the chosen process and the methods that have been conducted in the project. The result of the studies and investigations is shown in chapter 5. The report ends with a discussion, conclusion and recommendations in chapter 6.
CONTEXT 2
2 Context
This chapter describes the different levels of autonomous driving, along with when some car manufactures are expected to deliver these vehicles. The history of the seat belt and to what extent it is being used is also covered. The chapter ends with a benchmarking that covers prod- ucts and devices that counteract the submarining phenomenon.
2.1 AUTONOMOUS DRIVING
2025AD (n.d), a website powered by Continental, has created an autonomous driving (AD) time line that illustrate the milestones in the field of autonomous driving. The time line include an iconic image of automated driving, which was first shown in 1957, see Figure 2. The image indicates that the idea of highly automated vehicles have existed for at least 60 years.
Some automotive manufacturers are at level
1 or 2, while others have deployed level 3 vehicles on the road (Boeriu, 2017). See the defined levels in Figure 3.
FIGURE 3. SAE´S DEFINITIONS OF AUTONOMOUS DRIVING LEVELS
Autonomous levels
SAE International (2016) has defined 5 levels of automation in on-road motor vehicles. This thesis will be based on SAE’s definition of the autonomous levels.
FIGURE 2. ICONIC IMAGE OF AUTOMATED DRIVING
Volvo Cars and level 4
Volvo Cars has as an objective to put 100 unsupervised autonomous driving cars on the roads of Gothenburg by 2017 as a part of their “Drive Me - self-driving cars for sustainable mobility”
research project. (Volvo Cars, n.d.). These cars reach level 4 (high automation) on SAE International’s automation scale.
Volvo Cars states that their level 4 HAD vehicles will be able to navigate without human input.
In order to navigate, the cars will use sensors that read the surroundings and adapt through changing traffic conditions. The cars will be able to steer, brake and accelerate whilst in unsupervised autonomous mode and the car occupants are not expected to have control of the vehicle (Volvo Cars, n.d.).
The cars that are a part of Volvo Cars’ “Drive Me” research project, are early prototypes and will need supervision from the occupant in the driver seat. However, Volvo Cars believe that their first level 4 HAD vehicle, that does not need supervision, will be on the market by year 2021 (Volvo Cars, n.d). According to Mertens (in Berggren, 2016), the first level 4 HAD vehicles from Volvo will mainly be able to drive in autonomous mode on freeways and in commuting environments.
According to Peter Starke, Unit Program Leader of Autonomous Cars at Volvo, people will not be allowed to sleep in the first level 4 HAD vehicles. The car will be able to handle all possible situations that can appear where it is allowed to have the autonomous mode activated. The driver will never have to take control over the vehicle on short notice. See appendix 3 for the whole interview (P. Starke, personal communication, 2017 March 13).
Mercedes and level 4
The most autonomous cars from Mercedes have reached level 2 on the autonomous scale. The goal is to reach level 4/5 of autonomous driving by year 2025. Mercedes see the autonomous development as a journey of building blocks. Until the goal is reached, Mercedes want to give some of that technology to the customer along the way (Ola Källenius, 2017).
BMW and level 4
At the Customer Electronics Show (CES) 2017, BMW demonstrated how someone’s life could be in 2022 with one of their future level 4 car. The vehicle will be able to load your destination before you step into the car, using a “Mobility Cloud” system. The intention with the BMW’s Mobility Cloud is to allow the car occupants to decide what they want to do with the time they spend in the self-driving car (Boeriu, 2017).
Other companies that develop self driving cars are:
Tesla, Uber, Google, Toyota, Nissan, Ford, General Motors & Lyft, Audi, Baidu, Honda, Hyundai, Bosch, PSA Groupe, Faraday Future, LeEco and Apple (Muoio, 2016).
2.2 HISTORY OF THE SEAT BELT
The history of the safety belt goes more than a hundred years back. The first patent of a safety belt for passengers was granted to Edward J. Claghorn in 1885. The belt was provided with hooks and attachments for securing a person to a fixed object. During the first half of the 20th century, the safety belts were mostly used in aircrafts (Journath, 2005).
During the 1950s a thousand people were killed every year in the Swedish traffic, and the number continued to increase. Lennart Lindblad, founder of Autoliv Development AB, became a pioneer in seat belt technology when the company started the production of the two-point seat belt. The trigger of the seat belt development was an incident during a road trip with the
Lindblad couple. A serious car accident occurred close to their home and Lindblad got worried for his wife’s security. He found a seat belt advertisement in the newspaper and bought one.
The seat belt was a disappointment and Lindblad decided to develop one himself (Westergård, 2016).
After the Second World War, the Swedish company Vattenfall expanded, and the number of work-related accidents increased. Between 1953 and 1954 Vattenfall had about 1500 vehicles within the company and something had to be done to prevent the accidents. Two engineers at Vattenfall, Bengt Odelgard and Per-Olof Weman, were given the job to develop a seat belt directly to Vattenfall. It resulted in a diagonal seat belt which they started fitting in their vehicles in 1956. The idea of equipping cars with seat belts was later presented to the Swedish manufacturer Volvo. In 1958 the first modern three-point belt was patented by the safety engineer at Volvo, Nils Bohlin, and in 1959 it was standard equipment in Volvo Amazon (Vattenfall, n.d.).
In 1963 Volvo made the three-point seat belt a standard in front seats in America. The seat belt was compulsory in both the front and rear seat in 1986 in Sweden. Only three years later it was compulsory in 34 of the states in America (The Royal Society for the Prevention of Accidents, n.d.).
Ever since the seat belt was first introduced in automobiles in the 1950s, it has been estimated that more than a million people have been saved because of the seat belt (Autoliv, n.d.).
2.3 CURRENT STATE
Frontal collisions typically occur when the driver crosses the centerline and crashes into a forthcoming vehicle. According to National Highway Traffic Safety Administration´s (NHTSA) Fatal Analysis Reporting System (FARS), 75% of these types of accidents occur on rural roads.
These roads are often two-laned and undivided, which makes the risk for frontal collision higher than on any other types of roads (Safety Transportation, 1999).
Seat belt usage
The seat belt usage in private cars differ from country to country. In 2014, 97% of the people in Sweden seated in the front seat were wearing seat belts. According to the Swedish Transport Administration, the goal is to reach 99% in 2020 (Trafikverket, 2015). In 2016, the seat belt use reached 90% in the United States. Seat belt usage is higher in the states where the occupants can be pulled over solely for not using a seat belt, compared to the states where the enforcement laws are weaker (NHTSA, 2016). In India, for example, the seat belt use in the front seat year 2013 was only 26% (World health organization, 2015).
As mentioned, not all people wear seat belt, some people just wear it occasionally and others never wear it. In the US, adults in the age of 18 to 34 are less likely to wear seat belts than those 35 years and older. Males are 10% less likely to wear it than females, and teens have the lowest seat belt use (Virtual Drive USA, n.d.). The primary reason why people wear seat belt occasionally is because they are only driving a short distances (56%) Half of them also tend to simply forget on occasion. For the people who never wear seat belts, the most common reason is that they experience the seat belt as uncomfortable (65%) (US Legal, n.d.). The most common reasons why teens are not wearing seat belts include, apart from the previously mentioned ones, the lack of understanding why it is important (Virtual Drive USA, n.d.).
Safety regulations
United Nations Economic Commission for Europe (UNECE) (2012), have safety regulations that vehicles have to meet in order to be approved. These regulations state that the lap belt in
motor vehicles shall have an angle (form the horizontal) within the range of 30 to 80 degrees (other than buckle side). On the buckle side, the range shall be within 45 to 80 degrees. These requirements shall be valid in the front seat for all normal traveling positions. At least one of the these angles shall be constant (e.g. anchorage fixed at the seat), with a value of 60 ± 10°. With a seat back angle of less than 20 degrees from the vertical, the angle may have a minimum value of 20° (other than buckle side).
There are regulations of locations where the lap belt anchorages should be positioned in order to be effective. In the front seat, the anchor points should be positioned with a minimum distance of 125 mm from the seat reference point (SRP) and 350 mm from the opposite anchorage (UNECE, 2012).
2.4 BENCHMARKING
Before reading the benchmarking chapter, the reader is recommended to read the Submarining section in the Theoretical framework (page 21), in order to learn what causes submarining. With respect to the future concepts presented in the theoretical framework section, it seems that modern anti-submarining devices and other countermeasures can be used in some extent even in highly automated cars, especially for upright seating positions. These countermeasures will be described in this section. Some of the presented countermeasures are already implemented in today’s cars, and some have not yet reached that stage.
The benchmarking was conducted as part of a literature review where the submarining phenomenon was investigated. Articles and books were the main source of the benchmarking.
5-point seat belt
The 5-point seat belt is often used in off-road vehicles.
The belt has two shoulder mounts, two lap belt mounts and also a strap between the passenger’s legs, which is called “anti-submarine strap”. The anti-submarine strap prevents the passenger from slipping underneath the lap belt. The 5-point seat belt is therefore one of the most secure restraint systems available (Seat belts plus, 2016).
6 or 7-point seat belt
Racing cars tend to pack drivers in a more reclined posture compared with an SUV, see Figure 4 (Thomas & Smith, 2015). Sports cars with reclined driving positions must therefore have either 6-point or 7-point harness together with other anti-submarining devices. The lap belt must also have an angle between 60 and 80 degrees to the horizontal, in order to prevent submarining (Royce, 2011).
Seat belt buckle height adjustment mechanism
It is a telescoping seat belt buckle design which improves the buckle accessibility and comfort, see Figure 5. It adjusts the length of the seat buckle in order to maintain an optimal relation between the buckle position and the seat cushion position (Yilma, 2014).
Anchorage device fitted on the support frame
The anchor point is movable along a side on the support frame of the seat cushion, see Figure 6. The slide is connected to the lower part of the seat back. When the seat back is reclined, the anchor point slides to improve the effectiveness of the seat belt in reclined positions (Magneval
& Aoudia, 1994).
Motor vehicle seat part comprising an anti-submarining crosspiece
FIGURE 4. 6-POINT SEAT BELT.
It is a seat cushion that includes an anti-submarining cross member to limit the forward movement of the occupant’s pelvis, see Figure 7. The cross member extend crosswise to the top of the seat cushion framework. The cross member prevent the occupant from sliding (Alain, 2003).
Pretensioners
Pretensioners prevent the seat belt to slack by retracting the belt in the instant prior to impact (Smith & Hall, 2005). Sensors detect when a collision is inevitable and activates the pretensioners as a result (Kompass et al, 2014). There are two main types of pretensioners; spring tension and pyrotechnic. These units have to be replaced once deployed (Denton, 2004).
PrePretensioner
A reversible electromotive belt retractor (PP) can contribute with safety potential by gently tightening the seat belt after the occupant has buckled it. It can also more strongly pretension the belt in dangerous driving situations. PP counteracts the forward displacement of the occupants and consequently reduces the damaging forces on the occupants during a frontal collision (Kompass et al., 2014).
Force limiters
Force limiters, also known as load limiters, allow the belt to yield slightly in the event of a collision to minimize excessive force to be applied on the occupant. The force limiter activates if the force on the occupant’s body becomes too high (Smith & Hall, 2014).
Development of conventional seat belt
A different kind of seat belt, the Life belt, is provided with an extra continuous lap loop that is shown to give a high level of anti-submarining performance. The Life belt is able to reduce the need for other anti-submarining devices, the pretentioners for example (Gibson et al., 2011).
A possible solution to counteract submarining is to integrate the seat belt anchors into the seat itself, known as “all belts to seat” (ABTS) or “belt in seat” (BIS). This design could be beneficial when the seat back is reclined, but it doesn’t eliminate the danger of submarining completely (Emison, 2010).
Anti-submarining seat
An anti-submarining seat has a cushion frame that slopes upward toward the front of the seat. A cushion frame that has proven to counteract submarining had an upslope angle of 13-14 degrees (Thorbole, 2015). The seat presses the occupant’s thighs and pelvis during a frontal collision and helps to prevent the lower body from sliding under the lap belt. Together or separately with the sloping cushion frame, there is an anti-submarining air-bag that is placed in the cushion under the occupants in the front seats. The air-bag inflates in the event of frontal collision and reduces the pelvis forward motion (Smith & Hall, 2005).
Make safety instructions more available
Restraint instructions should be clear and stress the hazards of misuse (Lovesey, 1993). A cheap way to prevent misuse (seat backs that are too reclined for example) is to implement a warning system (visible or audible) that reminds the occupants of the proper seat belt use, seating configuration, etc (Emison, 2010).
Adaptive restraint systems
Adaptive restraint systems classify the occupants at the beginning of the trip. This could be done by seat cushions that are pressure-sensitive and detection of the longitudinal seat position.
When the classification is done, the restraint system can adapt according to the occupant’s
features. In the future, this function could be enhanced by using multiple sensors that measure crash conditions and occupant characteristics, such that the optimal protection can be provided for the occupants (Kompass et al., 2014).
Optimal seating position
Modern technology makes it possible for occupants to be moved to optimal seating positions using reversible actuators. With this solution, both the vehicle structure for energy absorption and the restraint systems can reach its full potential. However, faster seat motors are needed to increase the chances of achieving the safest seat position within the pre-crash that is detected by environmental sensors (Kompass et al., 2014).
Another solution is to prevent seats from reclining beyond a specified angle while the car is in motion. This alternative may be the most controversial (Emison, 2010).
THEORETICAL 2
FRAMEWORK
THEORETICAL FRAMEWORK 3
3 Theoretical framework
The theoretical framework is used as a foundation on which the concept development is based on. This chapter will present the result from a literature review where the submarining phenomenon, ergonomics and anthropometry were studied. The field of Industrial Design Engineering has also been reviewed in order to provide the reader with an insight in how industrial design engineers approach a product development project.
3.1 INDUSTRIAL DESIGN ENGINEERING
The fields of Industrial Design and Engineering Design will be described in this section in order to provide an insight in how industrial design engineers work.
3.1.1 Industrial design
The definition of Industrial Design has changed several times over the years and the first definition, from 1959, states that industrial designers use their training, technical knowledge and visual sensibility to develop a product. They determine the shape, color, mechanisms, materials, decoration and surface finishes of the product with the intension to produce it in large quantity by industrial processes (World Design Organization, n.d.).
In 2015, the Professional Practice Committee unveiled a renewed definition of Industrial Design which states that Industrial Design is a trans-disciplinary process that drives innovation. It leads to innovated products, systems, services and experiences that improves the quality of life. To accomplish this, industrial designers use human-centered processes in order to acquire deep understanding of user needs (World Design Organization, n.d.).
Industrial Designers of America (n.d.) describes Industrial Design as a professional service of creating systems and products that optimize value, function and appearance for the benefit for both the manufacturer and the user. Industrial designers collect and analyze data with the guidance of special requirements of their client and manufacturer. Clear recommendations are then presented through drawings, models and descriptions. They often work in multi- disciplinary teams that include management, engineering, manufacturing specialists and marketing (Industrial Designers of America, n.d.).
3.1.2 Engineering design
Pahl, Beitz, Feldhusen, Grote and (2007) have described the tasks and activities that engineering designers (or design engineers) are performing in their profession. They mention that engineering designers’ main task is to use their engineering knowledge to solve technical problems. The solutions shall then be optimized with respect to constrains and requirements set by human- related, environmental, technological, material, legal and economic considerations. The product development can be conducted through individual work as well as in interdisciplinary teams.
Dym and Little (2009) have stated a definition of engineering design. They mention that it is an intelligent and systematic process where designers generate, evaluate and specify design for systems, devices or processes that meet users’ needs and clients’ objectives while satisfying specified constrains.
3.2 SUBMARINING
The most important safety device during a vehicle collision is the seat belt. The majority of
today’s cars are equipped with the conventional single loop 3-point belt systems. The shoulder anchor point (D-Ring) in the belt system is usually fixed on the B-pillar (Thorbole, 2015).
The seat belt has a central role in this section where it’s a part of the unwanted
phenomenon called submarining. An explanation on what submarining is will be provided along with what causes the phenomenon. Some countermeasures on how submarining can be prevented in HAD vehicles is covered in the previous Benchmarking section.
3.2.1 What is submarining?
As mentioned in the introduction, submarining is phenomenon where the occupant slides under the lap belt in a frontal collision. (Hermitte & Labrousse, 2012). When the occupant slides, the pelvis rotates as seen in Figure 5. The lap belt is then unable to restrain the occupant in the designed manner as it passes above the bony pelvis. (Eggers et al, 2016). The occupant’s abdomen is then exposed to the force of the lap belt and can therefore be seriously injured. (Kim et.al., 2015). The injuries caused from submarining can in the worst cases be fatal (Hermitte &
Labrousse, 2012).
3.2.2 What causes submarining?
This section will provide a list of what could cause submarining. Firstly, some seat belt related causes will be covered and at the end of the section, causes related to the car’s owner’s manual will be described.
Seat belt used the wrong way
An occupant could be subjected to submarining if the lap bet is initially positioned high on the abdomen (Stockman, 2016), see Figure 6.
Slack in seat belt system
The seat belt’s restraint abilities are negatively affected if there is slack in the seat belt system in relation to the occupant’s body. Obesity effectively causes slack in the seat belt system by increasing the distance between the seat belt
and the skeleton. The increased distance between the pelvis and the belt results in a higher risk for submarining during frontal crashes. (Reed, Ebert-Hamilton & Rupp, 2012) .
Crash tests´ inaccuracy with reality
The fact that cars have been designed for humans and not crash test dummies, calls for a closer look on how crash tests are arranged in order to develop the best suited design solution. When
FIGURE 5. THE PELVIS ROTATES FROM THE GREEN AREA TO THE RED WHEN SUBMARINING OCCURS.
FIGURE 6. SEAT BELT POSITIONED ON THE ABDOMEN
observing occupants in cars, it’s safe to say that they take a variety of seating positions. Positions that might not be tested in crash tests. The position of the driver in the crash tests closely corresponds to the seating position in the real world. This is due to the fact that the driver has to reach the pedals and the steering wheel as well as maintain good view of the vehicle exterior and the instruments. The driver’s positions are therefore geometrically constrained within narrow limits. For the passenger, those limits do not apply. The passenger’s seating positions is consequently influenced by predominantly comfort aspects (Kompass, Schweigert, Gruber, Domsch & Kates, 2014).
According to Euro NCAP (2011), the seat back should have an angle of 25 degrees when evaluating crash safety. How reclined seats affect the risk for submarining can be read about later in this section.
There are no safety regulations that take into account that drivers often brake before collision.
In reality, car occupants are often placed in a forward displacement due to the deceleration of the car, which is a result from the braking of the vehicle, see Figure 7 (Kompass et al., 2014).
The HIII dummy is frequently used for safety assessment Richard et al. (2015) . This dummy is provided with a very stiff lumbar spine, which prevents the pelvis rotation and therefore also the submarining phenomenon. In other words, the biofidelic behavior of the dummy does not correspond well enough to humans’ biological features (Couturier, Faure, Satué & Huguet, 2007). The seat belt force that causes injury is very sensitive to the configuration of the dummy’s abdomen as well for the material property of this area (Kim et al., 2015).
Seating positions
The results from a crash test showed that a slouched position of the dummy led to the most severe submarining. This position is commonly chosen by children who are too small for the standard rear seat environment (Brown, Beck & Bilston, 2011). However, Uriot et al. (2015) states that a slouched position doesn’t necessarily result in submarining, if certain anti-submarining devices are used (lap belt load limitation at 4 kN and a pretension system).
Passengers often keep the seat position that was previously set, only to save the trouble of positioning the seat. This could result in a less favorable position for a crash (Kompass et al., 2015).
Submarining occurs most frequently when the occupant is sitting on the seat edge and/or if the seat back is significantly reclined. In these cases, the seat belt fails to restrain the occupant in the intended manner (Thomas &Smith, 2015).
Reclined seat
Reclined seats may satisfy the comfort needs of some passengers, but a highly reclined seat back is not recommended for safety reasons (Kompass et al, 2014). With highly reclined seats comes greater submarining risks due to the impairment of the belt fit in relation to the occupant’s body. (Thorbole, 2015). Tang & Liu (2012) conducted a study where the objective was to find out what it takes to make a reclined seat as safe as an upright seat. They used a modified FTSS HIII 5th percentile female dummy model (Version 5.1) in order to investigate at what angle on the seat back that make the seat more likely to cause submarining. The result showed submarining when the seat back had been reclined to 45 degrees. However, there
Unknown
>6.0 m/s2 4.1-6.0 m/s2 2.1-4.0 m/s2 0.1-2.0 m/s2
No breaking Positive acceleration
FIGURE 7. PERCENTAGE OF PEOPLE WHO BREAK BEFORE FRONTAL COLLISION
was no indication of submarining when the seat cushion was angled and provided with extra support. The extra support could however cause discomfort if it was placed too high.
The lawyer Kent Emison won a $59 million verdict against Toyota on behalf of a man who had a car accident whilst his seat was reclined. The man had to amputate both legs below the knees due to the injuries (Emison, 2010).
Biss (2011), who has consulted over 30 reclined seat cases, mentions that the automotive industry does not take responsibility for the hazard of reclined seats. They shun the responsibility by saying; “Everyone knows it’s dangerous”, “It is common sense” and “It is spelled out in the Owner’s Manual” (Biss, 2011). An example of a warning stated in the Owner´s manual is “Do not incline the backrest on the front passenger side too far to the rear during driving, or there is a risk of slipping under the safety belt in the event of an accident. This would eliminate the protection normally provided by the belt” (BMW, 2012).
Users do not read the owner´s manual
A study by Leonard (2001) shows to what extent car users read the Owner’s Manual where safety instructions are stated. 62% read parts of the Owners manual and 2% of these read the safety section in the Owners manual.
3.2.3 How will the seating situation be in highly automated cars?
The seating in highly automated cars is likely to offer a wider range of seating possibilities for the driver. Figure 8 shows some future semi-realistic concepts designed by selected car manufacturers.
BMW
Volvo Mercedes
FIGURE 8. MERCEDES´F 015 LUXURY IN MOTION. A CONCEPT OF A FUTURE HIGHLY AUTOMATED VEHI- CLE. VOLVO´S CONCEPT 26. A CONCEPT WITH THE POSSIBILITY TO RECLINE THE SEATS. THE BOOST AND EASE MODE, A PART OF BMW´S VISION NEXT 100. THE EASE MODE ALLOWS THE OCCUPANT TO SIT
3.3 ERGONOMICS AND ANTHROPOMETRY
Knowledge within the field of ergonomics and anthropometry is considered necessary in order to develop a restraint system that suits a wide range of the target group.
Ergonomics is the science of human work, it means the interaction between the people and the way the work is done. It includes the equipment that people use, the places they work in and the psychosocial aspects of the situation. The word “ergonomics” comes from the Greek where ergos means work and nomos means natural law (Pheasant & Haslegrave, 2005).
The definition of work is in this context defined by in how it is performed rather than its content.
Ergonomics is concerned with the design of the tools, artifacts and environment for human use.
An object, system or environment that is intended for human use should be designed based on physical and mental characteristics of its users. Ergonomics is about achieving the best possible match between the product and its users in context of the task being performed, the principle of user-centered design. Consequently it is about fitting the job to the operator and the product to the user. Some important criteria that define a successful match are functional efficiency, ease of use, comfort, health and safety and quality of working life. A product that is easy to use is in general both safe and efficient, which in turn is paid off in terms of productivity (Pheasant
& Haslegrave, 2005).
Anthropometry is an important branch of ergonomics (Pheasant & Haslegrave, 2005). The word anthropometry derives from the two words anthopos and metrikos, which means human and pertaining of measuring (Rosebuck, 1995). It is the part of human science which deals with body measurements, particularly body size, shape, strength and working capacity (Pheasant
& Haslegrave, 2005). Human beings are variable in all these characteristics, which mean that designing for the human requires a great understanding for this variability. The statistical description of human variability can be described in a frequency distribution for statures, see Figure 9. The curve is symmetrical about its highest point, the average stature. Probability is on the vertical axis and stature is on the horizontal axis. The curve is symmetric so it means that 50 percent of the population is shorter than average and 50 percent are taller. That means that, in this distribution, the average is equal to the 50th percentile. In general n percent of people are shorter than nth percentile. Near the end on the left-hand side of the horizontal axis, there is a point where it can be said that exactly 5 percent of the people are shorter than this, which is known as the 5th percentile (Pheasant & Haslegrave, 2005).
FIGURE 9. STATICAL DESCRIPTION OF HUMAN VARIABILITY
1 5 50 5 1
Percentile
An equal distance towards the end on the right-hand side is a point of which can be said that only 5 percent of the people are taller than this, that point is known as the 95th percentile. 90
percent of the population is in between the 5th and the 95th percentile in stature. Percentiles are specific to the dimensions they describe, which means that a person who is a specific percentile in stature may not be the same in waist circumference or shoulder breadth. As said, people are variable and differ in shape as well as in size (Pheasant & Haslegrave, 2005).
3.4 ANTHROPOMETRIC ASPECTS OF SEAT DESIGN
The seat design is an important factor in how people experience comfort. Seat back dimensions and angles are aspects that have a great impact on the user depending on the dimensions (Pheasant & Haslegrave, 2005).
Seat back angle
When the seat back angle increases, a greater portion of the weight of the trunk will be supported since the compressive force between trunk and pelvis is decreased. When increasing the angle between trunk and thighs it also improves the lordosis. However, the horizontal component of the compressive force increases. This tends to drive the buttocks forward and out of the seat if not counteracted by a seat tilt, high friction upholstery or muscular effort (Pheasant & Haslegrave, 2005).
Seat angle and tilt
A seat with upward slope helps the user to have a good contact with the seat back and counteracts any tendency to slide out of the seat. An excessive tilt will reduce the ease of standing and sitting up though. A tilt of 5 to 10 degrees is a preferably compromise (Pheasant
& Haslegrave, 2005).
3.5 COMFORT
People spend a significant time travelling nowadays, which means that there is an increasing demand for comfort in private and public transport (Gaminero da Silva, 2002). Producers and designers see comfort as a major selling point because of the increasing role it seem to play in a buying decision (Pennestri, Valentini & Vita, 2005). The practice is to design automobile seats that satisfy the ergonomic criteria related to anthropometry, which is considered a key aspect when it comes to comfortable seating. Automobile seats are specified by the anthropometric dimensions for the target population. The designers must ensure that the seat is designed so that a wide range of people fit in the seat, from the 5th percentile female to the 95th percentile male (Kolich, 2003). Good riding conditions results not only in better performance by the driver, but also a decreased exhaustion of the passengers (Gaminero da Silva, 2002). Human factors and the study of how seats can be designed better for human use is therefore an important part in vehicle seat design today (Jhinkwan & Singh, 2014).
The comfort concept is very subjective, and what seems comfortable for one person may not be as comfortable for another. That is why there is no universally accepted definition of comfort (Pennestri et.al., 2005). Some researchers define comfort as “the absence of discomfort (Hertzenberg, 1958), “a pleasant state of physiological, psychological and physical harmony between a human being and its environment”, or “comfort is a state of a person involving a sense of subjective well-being, in reaction to an environment or situation” (De Looze, Kuijt- Evers & Van Diee, 2003).
METHOD AND IMPLEMENTATION 4
4 Method and implementation
The user is the center of attention in this master thesis. Therefore, the methods have been conducted from a human-centered point of view in order to obtain knowledge about the people we are designing for. The chosen process, planning of the project and the context immersion, will be described in this chapter.
4.1 PROCESS
In order to properly plan the project, the objective and aim with the project had to be defined.
Continuous conversations with the supervisor from Autoliv helped to define the objective and aim. How to approach the project was later investigated. To determine the approach, a literature review was conducted to find relevant product development processes that could be used in this project. Since the project puts the human in focus, it was considered that a human-centered process would suit the project. After searching for human-centered processes in articles, books and websites, we found an ISO standard that graphically describes how a human-centered process should be conducted. The process consists of phases that should be performed in an iterative manner, see Figure 10.
FIGURE 10. HUMAN-CENTERED DESIGN PROCESS
4.2 PROJECT PLANNING
The methods that the phases consist of could be determined after the process was chosen. The methods that were used in the project were mainly determined at an early stage of the project.
As the project progressed, new methods were added to the project plan. These methods were considered necessary in order to obtain better results from the different phases. The predetermined methods had a short description in the project plan and were described more thoroughly as the project proceeded. The longer descriptions of the methods can be read in later in this chapter.
The extent of the methods and when they would take place were visualized with a Gantt-chart, see first version of the chart in appendix 1, using the web-based platform GanttPro. The extent of the methods was reviewed by the supervisor on Autoliv. The Gantt chart was then updated based on the feedback from the supervisor.
We assigned different roles that we would have during the project. Roles such as Project leader, Secretary, Photographer etcetera were assigned. Since we are a small team, it was considered that the roles could be flexible throughout the project.
4.3 CONTEXT IMMERSION
In order to obtain an understanding about the context of this thesis, several methods have been used. We started with a literature review followed by more practical methods that include the user.
4.3.1 Literature review
It is important to conduct a literature review when you wish to acquire an understanding of a specified topic (Hart, 1998). In our pursuit to gain knowledge, articles and books were the main sources. When we found a viewpoint on the topic from an author, we tried to find if another author shared that viewpoint or had a different one. The purpose with this approach was to make sure that the theoretical framework, context and benchmarking provide valid information.
Different data bases was used in order to get access to relevant articles. Data bases used were:
Google Scholar, IRCOBI and Ergonomics Abstract. Regular Google-searches were also a tool that we used in order to find articles. In the literature review, we explored the submarining phenomenon, ergonomics & anthropometry, autonomous vehicles and the history of the seat belt.
4.3.2 Focus group
In order to investigate people´s experiences, thoughts and knowledge regarding future autonomous cars, a focus group was conducted. The expected outcome of the focus group was to get a greater understanding about how people from a potential target group of the future HAD vehicles, think and reflect about future autonomous cars.
A focus group is a qualitative research method. It is a form of group interview which takes advantage of the communication and interaction between research participants in order to generate rich data. The participants are encouraged to talk, exchange stories, ask questions and comment on each other’s point of view. The method is mainly useful for exploring people´s experiences and knowledge in order to analyze what people think, how they think and why they think the way they do. There is one facilitator that controls the group and asks questions, preferably open questions so that the research can lead to new and unexpected directions.
Group processes can help people to explore and clarify their thoughts which are harder in a one-to-one interview. (Kitzinger, 1995).
Since the focus group is based on group interaction, it is important to make a climate where the participants feel comfortable talking and expressing themselves. The selection of people is therefore valuable (Rabiee, 2004). Homogenous groups, where the participants share the same characteristics such as age-range, gender, ethnic and social class are an advocate in order to get the best result. It is also preferable to use pre-existing groups, because people who have a connection can easier relate to each other and have the courage to challenge each other (Kitzinger, 1995).
Small groups with four to six members may be the most productive, since that encourages the participants to take place and to be a part of the discussion. Larger groups can be hard for the facilitator to control (Mousa & Masadeh, 2012).
Implementation
We asked the participants about their interest in having a future autonomous car, how their seating positions would look like, entertaining activities, need of sleeping and sight, and the restraint system. For a clearer view of the questions and the layout of the questionnaire, see appendix 2. The focus group consisted of a homogeneous and pre-existing group of four men in the age range 23-25 years, who all study Industrial design engineering.
One day before the session started, the group was sent an introduction of the project and background information about the topic, in order to prepare them for the upcoming questions.
The background also consisted of a video of the Concept 26 created by Volvo, where they got familiar with how the future level 4 HAD vehicles could look like.
Since the participants were located in Luleå, the session was performed over Skype. We, as facilitators, had a group room at Chalmers Technical University with computers and a questionnaire. One of us was the facilitator and the other one documented everything that was said during the session. The facilitator controlled the discussion and kept the questions open since that encourages the participants to explore the issues of importance and make their own priorities. Some of the questions were:
• Would you like to buy a self-driving car? Why?
• How would you like to sit in a self-driving car?
• Would you feel safe when traveling in a level 4 HAD vehicle?
The session lasted for one and a half hour and the participants got to discuss their thoughts and feelings considering the questions of interest. Since the participants were located together at the same place, they could easily interact with each other and use both verbal communication and use body language in order to express themselves.
The result of the focus group was compiled and the comments of each questions was characterized. From that, key words were found in each category. Key words and interesting quotes were compiled into a poster to visualize the result of the method.
Method discussion
To get a wider perspective, a focus group session with females should also have been conducted.
Since we knew the participants from before, it was easy to communicate and discuss. This might have encouraged them to share their needs and thoughts.
There were some communication difficulties during the Skype session. If we all were located at the same place, the communication between the participants and us would have been easier.
This might have improved the flow of the discussion and led the group into other interesting topics.
4.3.3 Interviews
Interviews were conducted in the context of identifying user needs. Users were therefore asked questions during the later described Clinic 1 and 2. Also, an interview was conducted in order to identify the intended target group which car manufacturers might have in mind for the level 4 HAD vehicles.
Interviews could be conducted during several stages in the design process. Before interviews are used as a data-collecting method, the purpose of the collected data should be specified (Kylén, 2004). Kylén also mentions that the accessibility, competence and resources of those who collect and compiles the data affect when the method is used.
How can a designer know what customers are looking for in a particular type of product? A market survey could answer this question. Eppinger & Ulrich (2011) mention that interviews are commonly used in order to identify these customer needs. In relation to other concept development activities, the identification of customer needs is conducted early in the design process. Johannesson, Persson and Pettersson (2013) also include the interview as a commonly used method in the market survey. But in contrast to Baxter, Johannesson et al. (2013) talks more about collecting the viewpoints and valuations of “soft” product features, instead of customer needs
What is an interview?
According to Kylén (2004), the interview is a meeting with one or several people. The purpose with the interview is to obtain information from the interviewee. To do that, the interviewer stimulates the interviewee to tell or answer different questions. The interviewer is taking notes and the notes are later analysed. According to Lantz (2007), the interview is an interaction between two people with different and unequal roles. One person asks the questions and the other answers. She continues by stating that the interaction is based on volontaryness. She also mentions that the communication between the interviewer and the interviewee, is the material that should be analysed. The communication that is in focus is mostly the verbal. But the non- verbal communication, such as body language, could be of interest depending on the purpose of the interview.
Quantitative and qualitative data
A data collecting method can either obtain quantitative or qualitative data. Quantitative data is often presented in numbers. Quantitative data could be obtained using interview as a method.
For example, if subjects are asked on a scale how comfortable a driver seat is, their answer is considered to be quantitative data (Bohgard et al., 2010).
However, interview is a method mostly used to collect qualitative data. The data is an understanding and a description of the world. The qualitative data answers the questions what, who, how, when and where. Qualitative data could be usability problems that are found during an interaction study. It could also be a user’s description of the pain caused by poor work postures (Bohgard et al., 2010).
What is a semi-structured interview?
A difference between a semi-structured interview and a structured is that the
interview questions don’t have to be formulated with the exact same words every time. The importance lies in the conveyed meaning of the questions instead of the words that form the questions. This way of conducting an interview is preferable if the responders don’t use the same vocabulary (Treece & Treece, 1986). In a semi-structured interview, the interviewer often start with the “structured” questions and then use follow-up questions to guide the conversation into interesting territory (Lantz, 2007).
Implementation
Semi-structured interviews was a part of the later described Clinic 1 and 2. This section will cover how we interviewed the Unit Program Leader of Autonomous Drive at Volvo Cars in Gothenburg. The result from the interview is presented in the previous context chapter. The objective of the interview was to collect information about what Volvo thinks the seating situation of level 4 HAD vehicles will look like and other questions regarding the autonomous technology, view the used questionnaire in appendix 3.
An interview form was created with respect to the interview objectives. The interview was conducted through telephone where one of us asked questions and the other one was documenting the answers. The interview started with an introduction of us and our thesis,
