Lifting the Load: Optimizing Dishwasher Ergonomics Through User-Centered Design Master’s Thesis in Industrial Design Engineering SARA HENRIKSSON, AMBER ÖSTBERG DEPARTMENT OF INDUSTRIAL AND MATERIALS SCIENCE CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden, 2025 www.chalmers.se Master’s Thesis 2025 Lifting the Load: Optimizing Dishwasher Ergonomics Through User-Centered Design Sara Henriksson Amber Östberg Department of Industrial and Materials Science Division Design & Human Factors CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden, 2025 Lifting the Load: Optimizing Dishwasher Ergonomics Through User-Centered Design © SARA HENRIKSSON & AMBER ÖSTBERG, 2025 Supervisor and Examiner: Lars-Ola Bligård, Industrial and Materials Science Department of Industrial and Materials Science Division Design & Human Factors Chalmers University of Technology SE-412 96 Gothenburg Phone +46(0) 31 -772 10 00 Thesis in collaboration with ASKO Appliances Cover Photo: Sara Henriksson & Amber Östberg Print: Chalmers Digitaltryck Gothenburg, Sweden, 2025 Preface and acknowledgements This master’s thesis project was performed in the spring of 2025 at Chalmers University of technology at the department of Industrial and Materials Science, for the master program Industrial Design Engineering, in collaboration with ASKO. The supervisor as well as the examiner for this project was Lars-Ola Bligård. From ASKO, the supervisor was Mikael Johansson. Firstly, we would like to thank Lars-Ola Bligård, the supervisor and examiner of the project. Lars-Ola have supported us in all parts of this project as well as helped us achieve our personal goals we set for the project. Secondly, we would like to thank the people at ASKO, and our supervisor Mikael, for all their support in discussions about concept realization and prototyping the final concept. It has been an experience where we have had the ability to grow, learn and create an outcome that we are proud of. Moreover, we would like to thank Lars-Olas colleagues at the department of Industrial and Materials Science, who have helped us with this project as well. Cecilia Berlin who helped with the user test setup and ergonomic assessments, Håkan Almius who helped with product renders and animations and Siw Eriksson who helped us combine user study tools to create our own method, a method we are proud to have included in this thesis. Lastly, we would like to thank all participants in the user studies. We would like to thank the physio- and occupational therapists, the kitchen architect and dishwasher retailer, for participating in the interviews. We would like to thank the participants in the user tests, and we would like to thank the participants in our own method Letters. This thesis would not be possible without you. Abstract Dishwashers are a widely used appliance in modern homes, yet their design has seen limited ergonomic innovation in recent decades. Most models remain standing on the floor, requiring users to bend down repeatedly during loading and unloading dishware, leading to physical strain on the back. This study aims to improve the ergonomics of household dishwashers by developing user-centered design solutions, in collaboration with ASKO. Through an iterative design process, the project used a range of methods to analyze the current situation regarding dishwasher ergonomics, gathering both numeric and qualitative data. The data was analyzed leading to the identification of pain points and user needs, and then the development of two ergonomic dishwasher solutions. A contemporary concept and a future concept. The contemporary concept features a built-in scissors lift mechanism in the door, allowing the users to work at an ergonomically optimized height when loading and unloading the dishwasher, where both the upper and lower basket can be reached simultaneously. The future concept features modular baskets that can be removed and moved to a better work height, such as the countertop, with handles for better grip. This concept is a holistic concept that blurs the line between the dishwasher and kitchen storage by providing the possibility to store the baskets directly in drawers and cupboards. Both concepts aim to reduce bending, improve posture, and support usability. Ergonomic evaluations indicate improvements compared to ASKOs dishwashers today, with lower strain on the body in critical tasks when using a dishwasher. Table of Contents 1 Introduction ........................................................................................................................ 1 2 Final Results ........................................................................................................................ 5 3 Kitchen and dishwashers .................................................................................................. 13 4 Ergonomics ....................................................................................................................... 16 5 Methods ........................................................................................................................... 19 6 General description and procedure .................................................................................. 25 7 Project execution .............................................................................................................. 28 8 Results of Emphasize phase .............................................................................................. 43 9 Results of Define phase .................................................................................................... 49 10 Results of Ideate, Prototype and Evaluate phases ............................................................ 64 11 Results of final concept..................................................................................................... 73 12 Discussion ......................................................................................................................... 85 13 Future Work ...................................................................................................................... 93 14 Conclusions ....................................................................................................................... 97 References ................................................................................................................................ 99 Appendix 1: Interview guides ................................................................................................. 101 Appendix 2: Letters ................................................................................................................. 103 Appendix 3: Competitor analysis ............................................................................................ 109 Appendix 4: Questionnaire answers ....................................................................................... 110 Appendix 5: KJ-analysis themes .............................................................................................. 111 Appendix 6: Complete list of user needs ................................................................................ 118 Appendix 7: REBA ................................................................................................................... 120 Appendix 8: PEPA .................................................................................................................... 128 Appendix 9: Pugh matrix......................................................................................................... 131 Introduction 1 1 Introduction This project will investigate the ergonomic challenges of using a dishwasher, address these challenges and design a more ergonomic dishwasher solution in collaboration with ASKO. This chapter will introduce the project by giving a background to the subject, followed by the projects aim and objectives. The chapter will also present the project’s demarcations as well as the report structure. 1.1 Background For thousands of years, dishwashing was a manual task, performed by hand. This changed in 1886 when the first dishwasher was introduced to the market (Rosa, et al., 2012). This marked the beginning of a gradual evolution in dishwashing technology. Since then, dishwashers have become increasingly common in households. Today, dishwashers are in many homes considered a necessity. These machines are used daily by a wide range of individuals, from children who struggle to reach the upper baskets, to elderly users who may struggle to bend down to access the lower ones. Since the invention of the dishwasher, the machines have become more standardized in size and format. A width of approximately 60 cm is common in households, typically integrated under the kitchen countertop. This standardization aligns with standard measurements of countertops, which make the installation more convenient. The more recent development of dishwashers has largely focused on digitalization, quality enhancements and energy optimization. In recent decades, user-centered design and design for accessibility have become central values in product development across many industries. While dishwashers have followed this trend to some extent, particularly in terms of interface design and wash cycle customization, the physical ergonomics of dishwasher use have seen minimal progress. Most dishwashers are still installed at floor level, requiring users to bend down repeatedly, which may lead to discomfort and physical strain. Although the fixed dimensions and format of modern kitchens making it difficult to deviate from these standards, the lack of ergonomic innovation in this area represents a notable gap in product development. In contrast, industrial dishwashers have seen significant advancements. In these professional work settings, dishwashers are considered essential work tools, and industrial kitchens are often designed to accommodate dishwashers at optimal working heights. This has enabled the development of more ergonomically adapted solutions that minimize physical and cognitive strain and support efficient workflows. Despite these advancements in professional settings, there are still only a few household dishwashers on the market that prioritize ergonomic design. While some alternative concepts exist, they are not widely known nor adopted as standards solutions. 2 Given the shift toward inclusive and user-centered design in other areas of product development, there is a clear opportunity to explore how household dishwashers can evolve to better support user comfort, physical accessibility and ergonomic well-being. 1.2 Aim The aim of this thesis is to enhance the physical ergonomics of household dishwashers. This, by creating a more user-centered and ergonomically optimized dishwasher experience that minimizes physical discomfort and improves usability. The focus will be on improving the ergonomics when the users interact with the dishwasher within daily use. 1.3 Objectives 1. Analyze the current ergonomic challenges of an ASKO dishwasher in everyday tasks. 2. Develop a redesigned dishwasher concept with enhanced ergonomic features. 3. Evaluate the final concept based on ergonomic performance. 1.4 Demarcations This thesis will not address specific electric or mechanical functions or features in the current and developed dishwasher solution. 1.5 Report structure Chapter 1, Introduction The report begins with an introduction describing the background, aims, objectives and demarcations of the report. Chapter 2, Final results This chapter includes the result of this project and its objectives. This means that the current needs regarding ergonomics in use of household dishwashers, concepts created to meet these needs, and the evaluation of these concepts are presented here. Chapter 3, Kitchen and dishwashers This chapter introduces and explains the current situation in household kitchens and presents ASKO dishwashers. Chapter 4, Ergonomics 3 This chapter presents the basic ergonomic theories that are of importance for this project. This chapter is divided into two parts; Physical ergonomics and Cognitive ergonomics. Chapter 5, Methods The methods used in this project are presented in this chapter. Chapter 6, General description and procedures This chapter includes the description of the project model, and its respective phases, on which the project is based. Chapter 7, Project execution In this chapter, the execution of the different phases in this project are explained. Chapter 8, Results of Empathize phase This chapter presents the results of the empathize phase, including results from pre-studies as well as the results from user studies. Chapter 9, Results of Define phase This chapter presents the results of the Define phase, including ergonomic assessments and KJ- analyses. Chapter 10, Results of Ideate, Prototype and Evaluate phases This chapter presents the results of the Ideate, Prototype and Evaluate phases, including idea generation, concept evaluations and prototyping. Chapter 11, Results of final concept This chapter presents the final concept, which resulted in a contemporary concept and a future concept. Chapter 12, Discussion This chapter will discuss the results in relation to theory, process and methods. The aims and objectives from the introduction chapter will be addressed and discussed. Thereafter the validation of results will be discussed, and finally sustainability and ethics of the project will be addressed. Chapter 13, Future work In this chapter, opportunities for future work are presented, such as user testing, further development and prototyping. Chapter 14, Conclusion This chapter presents the final conclusions of this master’s thesis. 4 Final results 5 2 Final Results This chapter includes the results of this project and its objectives, as can be read in chapter 1. This means that the current user needs regarding ergonomics in dishwashers, concepts created to meet these needs, and the evaluation of these concepts are presented here. For the complete results see chapter 8, 9, 10 and 11. 2.1 Results from user studies The user studies included interviews, user tests and a new method for qualitative data collection, all focusing on ergonomic pain points in dishwasher use. These user studies, after thorough analysis, resulted in a list of user needs, consisting of insights phrased as requirements (see Appendix 6: Complete list of user needs). The list of user needs included user needs from all parts of the user studies, the most urgent needs being the ones most frequently mentioned, observed throughout the study and most relevant for the scope. A selection of these urgent needs and sub-needs can be viewed in Figure 1: Urgent needs. Figure 1: Urgent needs 6 These needs were thereafter at the center of ideation, concept generation and evaluation to develop concepts that meet these needs. Furthermore, ergonomic assessments were carried out to investigate the ergonomics of the current ASKO dishwasher. These assessments were based on two ergonomic assessment methods: PEPA and REBA (see information about these methods in 5.2). The PEPA showed that the task of loading and unloading the dishwasher were the most straining tasks. Furthermore, the positions observed in the user tests received points ranging from 4 to 9 in the REBA worksheet, meaning medium to high-risk positions, with bending down to reach as the biggest cause for these points. 2.2 Final concepts Following an iterative development process, two concepts were designed that met the user needs on an equal level. One of the concepts focuses on minimizing bending by adjusting the lower basket to a more favorable working height, thereby improving both visibility and overview. This concept also reduces cognitive load by presenting the baskets at the same height, side by side, providing the possibility to view and work with both baskets at the same time. The other concept focuses on minimizing bends by providing the possibility to remove individual baskets and place them at a good working height on the countertop, or store directly in kitchen storage. This provides the possibility for adjustability, good visibility and provides adequate grip and enhances the feeling of being effective by eliminating the need for completing a full unloading sequence. Both concepts are also adapted for critical users. 2.2.1 Scissors-lift integrated in the door This concept features a built-in lifting function that changes how the users interact with the lower basket of the dishwasher (see Figure 2). The lifting function is inspired by the mechanics of a scissors lift, where the function is smoothly integrated into the dishwasher door. The user interacts with the solution by pressing a button, which initiates the elevation of the lower basket, elevating it to the same height as the upper basket, eliminating the need for bending. 7 Figure 2: Scissors lift integrated in the door In this concept the baskets are approximately 60 mm shorter in depth, to provide the possibility to work on the lower and upper basket at the same time (see Figure 3). Figure 3: Upper and lower basket at the same height 8 The raised lower basket improves the visibility and enhances the sense of proximity. Aside from improving back ergonomics by reducing the need to bend, this concept also minimizes awkward postures by increasing proximity. 2.2.2 Modular baskets The second concept is created with a holistic approach, redefining how the dishwasher functions in relation to kitchen storage. This concept blurs the line between storage and dishwasher baskets by introducing modular baskets. These baskets can easily be removed and placed at a comfortable working height (see Figure 4). Figure 4: Modular baskets1 The baskets can also be placed straight into kitchen drawers and cupboards, shifting the process from unloading each individual dish, sorting, and storing it, to simply lifting out a few modular baskets and placing them directly onto shelves and in cabinets. The modular baskets therefore act as an extension of the dishwasher (see Figure 5). 1 Picture published with permission from ASKO. Retrieved from ASKO (https://asko-shop.ch/products/dfi746u), edited by the authors. 9 Figure 5: Store in cabinets2 In Figure 6, a suggestion of how the modular baskets could look are visualized. The modular baskets are designed so that the user can place the baskets correctly in the dishwasher, using hooks that hang on the rods of the original baskets. Figure 6: Modular baskets 2 Picture published with permission from ASKO. Retrieved from ASKO (https://asko-shop.ch/products/dfi746u), edited by the authors. 10 In addition to simplifying the unloading sequence in terms of time, this concept also offers several ergonomic advantages when using the dishwasher. Firstly, since the user only needs to lift a few modular baskets instead of handling each plate or glass individually, fewer bends and rotations are required to perform the same task. Moreover, the modular baskets feature handles on each side, providing a more ergonomic grip compared to the pinch grip typically used when holding a small fork or the edge of a thin plate. Finally, placing the modular baskets on the countertop offers better visibility, which reduces cognitive load. 2.3 Final evaluation Figure 7: REBA of final concept3 The scissors lift concept received a score of 3, suggesting a low-risk position (see Figure 7). The main reason for these low points is the straight neck position, small trunk bend, steady posture on the legs and low extension of the arms and wrists. In this case, the person is also reaching for the plate furthest away from them, meaning that this concept would score even lower when grabbing plates closer to the body. This result suggests an ergonomic improvement in comparison to the ergonomic assessments performed on an ASKO dishwasher on floor height. 3 REBA- worksheet recreated based on McAtamney, L., & Hignett, S. (2000). Rapid Entire Body Assessment (REBA). Applied Ergonomics, 31(2), 201–205. This source also applies to all subsequent REBA-related figures in this report. 11 The modular concept combined with the scissors-lift concept also shows an improvement in an estimated PEPA, with several improved aspects regarding, for example, the back and precision work among others. For the complete evaluation, see chapter 11. 12 Theoretical Framework 13 3 Kitchen and dishwashers This chapter introduces and explains the current situation in household kitchens and presents ASKO dishwashers. 3.1 Kitchens today Modern kitchen design prioritizes a layout that have an efficient workflow, often organized around the “work triangle” (Baden-Powell, 2005). The triangle is a concept that connects the sink, stove and refrigerator, the most used places in the kitchen. With this layout, unnecessary movements are minimized, which enhances functionality. The work triangle is based on the typical work sequence used in the kitchen. Store, wash, prepare, serve and eat. Once the sequence is complete, there is a cleaning sequence; clear, wash up. During the activities of the sequence, some activities are repeated, for example the use of the dishwasher both during and after the first sequence. Moreover, Baden-Powell states that the modern kitchens are based on key dimensions for ergonomic efficiency, which plays a crucial role in reducing strain and improving comfort. The ergonomic key dimensions are for example measurements of reach, vertical dimensions of cupboards and countertop, as well as space between counters. These dimensions are based on both men and women, where a sweet spot has been sought that suit both taller and shorter people. For countertops, the standard heights are around 900 mm, a dimension that suits the average user for food preparations tasks. Appliances such as microwaves and ovens are more commonly installed at higher levels, around 1200 mm, to minimize back pain and provide a better overview. Dishwashers are available in several sizes, where the full-size models are about 600 mm wide x 850 mm deep. 3.2 ASKO dishwashers ASKOs products are characterized by their durability in all their product categories. (ASKO Appliences, n.d.) Their dishwashers are built to last for 20 years. The durability and robustness can, for example, be observed by the amount of steel the dishwashers are produced in (see Figure 8). However, not only do the robust materials such as steel make ASKOs dishwashers durable, but they also present the design expression of a sturdy and reliable machine, that retains elegant and sleek. This minimalistic Scandinavian design is seen in all ASKO products. 14 Figure 8: ASKO dishwasher 8 steel4 ASKO has in recent years focused on improving flexibility, the capacity of dishware, energy and water consumption. The biggest model of ASKO, XXL, has a capacity for washing 17 place settings (see Figure 9). Figure 9: ASKO dishwasher4 4 Picture published with permission from ASKO. Retrieved from ASKO (https://se.asko.com/kok/diskmaskiner/funktioner). 15 ASKO has developed various modular inserts when moving towards a more user-friendly and adaptable development. When there is an interaction with a part inside the machine, those parts are colored in a distinct yellow-green color (see Figure 10). This makes it easier for the user to know that there is a function to be used. Figure 10: ASKO color cue5 3.3 Affecting the results The information in this chapter has affected the results of this thesis by providing insights regarding raising the dishwasher, to provide a more ergonomic work position in the kitchen. This has in turn led to an improved working height in the final concepts. Moreover, the traditional work sequence in the kitchen has been investigated, and efforts have been made to optimize efficiency by the modular concept. Furthermore, information about standard heights and adapting the solution to both taller and shorter people has affected the result by hindering the final concept from resulting in a too high or too low working height. Regarding the information about ASKO dishwashers, this has affected the results by mimicking the form language of ASKO into the final concepts. Color cues have also been added to the modular concept to parts that should indicate a function or interaction point, to serve as a help to the user. Lastly, the concepts have been using mostly steel as seen in the ASKO dishwashers today to stay consistent to the expression of durability. 5 Picture published with permission from ASKO. Retrieved from ASKO (https://se.asko.com/dw60). 16 4 Ergonomics This chapter presents the basic ergonomic theories that are of importance for this project. This chapter is divided into two parts: Physical ergonomics and Cognitive ergonomics. 4.1 Physical ergonomics Physical stresses on the body can cause injury in tissues, organs, joints and muscles (Bohgard et al., 2009). The concept of load in physical ergonomics is related to physical stresses, which includes both static load and dynamic load. Static load entails long-term continuous load without any variation in force or muscle length, while dynamic load is the opposite, with changes in force or muscle length. Slightly higher static loads often result in impaired blood circulation and very often tiredness and pain. Lower static loads do not frequently cause any acute problems; however, all sorts of static load increase the risk for various types of illnesses of the joints and muscles in the long run. Dynamic work can also be seen as static from a physiological point of view even though there is movement involved. For example, when the force level applied to a curtain muscle remains the same, even though there is movement involved to complete the activity. Bohgard explains that an emphasis has for a long time been on reducing the size of loads within the field of ergonomics. Thus, a long list of aids has been designed to reduce the effort needed to execute an activity, and as a result, working life today often includes prolonged low loads instead. It has become evident that the duration and frequency are essential in understanding how quickly fatigue and pain arise. In many cases, a person experiencing discomfort does not understand what the root of the cause is because the loads are so small. Furthermore, monotonous repetitive work is also of importance in physical ergonomics. This could lead to chronic pain and discomfort, similarly to a sudden high load, due to its repetitiveness. It's also discussed by Bohgard that lumbago commonly is a result of unexpected load of the back in an unexpected direction. This is probably due to small displacements of the vertebrae in the back that in turn is due to insufficient preparation in stabilizing back muscles. The displacements are what causes pain. Epidemiological research shows frequent heavy lifting to be a risk factor in back problems where twisted or bent postures can increase these risks. Regardless of the work being “light”, prolonged twisting and flexing in the back often lead to back problems, both due to the load and the actual weight of the body itself. When it comes to standing work it’s highly dependent on the height above the floor at which the work is carried out. With too high working height, the arms are kept in a high position resulting in a heavier static load, which is unbeneficial from an ergonomic standpoint. On the other hand, if the working height is too low, the body must be bent forward, and that increases load on the back as well as neck muscles. 17 According to Bohgard, as a result of the different possible causes, spontaneous emergence and passing of back pain, it is difficult to provide engineers with specific musculoskeletal ergonomic advice on designing products better suited. However, it’s reasonable to conclude that a guideline would be to avoid working positions with deep and frequently repeated bends forward or a twisted bodily position. Hands and wrists are critical parts of the human body for one to be able to execute various tasks (Berlin & Adams, 2017). The hand, wrist and arm together form a structure that is especially complex and sensitive to injury in physical work. An injury in this complex structure could severely hinder a human from executing a large range of activities. Belin & Adams explain that hands are an important tool for gripping, with different functional positions depending on the amount of power and/or precision needed for a specific activity. The complex structures of the hand are not to be overloaded with unnecessary twisting and bending, instead, the hand should be as close to its resting position as possible. The resting position of the hand is when the wrist is straight, muscles are relaxed, and fingers are slightly curled. A few typical issues that could risk injury to the hand are repetitive tasks, high forces and incorrect grips. 4.2 Cognitive ergonomics The human cognitive abilities are a combination of certain skills: experience, attention, pattern- recognition, ability to focus, association, memory and the ability to sort information into categories (Berlin & Adams, 2017). A well-designed work system, focused on improving cognitive ergonomics, can decrease the impact of fatigue by minimizing the ability to execute a task incorrectly. A more demanding task needs carefully designed cues in products that humans use. According to Berlin & Adams the human cognitive processes are the handling of information. The combination of sensory stimuli, attention, perception, memory and interpretation, which combined result in a response, is what builds these processes or mental capabilities. When designing to support human mental capabilities there are some specific design principles aimed at supporting the capabilities attention, perception and mental models. Three of those principles are: Minimize time and effort for finding information, proximity (being close to the product, visibility and reachability) and legible displays. 4.3 Affecting the results In this thesis the literature has affected the results in regard to exploring and establishing the cause of back-related ergonomic issues, hand and grip related ergonomic issues and cognitive related issues. It has also guided the execution of the ergonomic assessments conducted. Furthermore, a favorable working height and its effect on visibility, reachability and proximity, the importance of correct grips and well-designed work systems has been implemented in the final results. 18 Methods 19 5 Methods The methods used in this project are presented below. The order in which the methods are presented is based on the five phases of this project: Empathize, Define, Ideate, Prototype and Evaluate. More about the phases can be viewed in chapter 6.1. 5.1 Methods of Empathize phase This section presents the methods of the Empathize phase. 5.1.1 Functional analysis A functional analysis is a method used to break down a product's functions (Johannesson, Persson, & Pettersson, 2018). The main function is the primary purpose of the product. This main function is divided into several sub-functions, which are necessary for the main function to work properly. Support functions are features that enhance usability and support the product's use but are not critical for the main function. 5.1.2 Semi-structured Interviews A semi-structured interview is a qualitative data collection method combining open-ended questions with a pre-defined interview guide (Knox & Burkard, 2023). It is a method widely used to obtain participants’ perspectives, opinions and experiences regarding a topic. 5.1.3 User based evaluation A user-based evaluation is a usability method where users participate directly (Bastien, 2010). Users are invited to carry out typical tasks related to a specific product, while their behaviors during usage of the product are observed and recorded with the goal of identifying design flaws that cause issues. Once flaws in the products design have been identified, design recommendations can be proposed to improve ergonomic qualities of the specific product. 5.1.4 Letters Letters are a method used for obtaining information from users in their home environment, using probes guiding the user to reflect on everyday tasks. This is a method combining diary studies and cultural probes to reach deeper thoughts from the participants. Instead of using a diary, the user receives letters to fill in by hand. See more information about the method letters in Appendix 2: Letters. 20 5.1.4.1 Diary studies Diary studies is a research method used to keep log of the participants’ thoughts, experiences and activities of a set time frame (Hanington & Martin, 2012). It is a useful tool for exploratory research, where the participants self-report their personal details. Diary studies can be more or less guided, depending on the context. The results are then analyzed by the researchers to understand habits and patterns. According to Hanington and Martin, diary studies are useful when the researcher wants to understand long-term habitual behaviors and user experiences across time. They allow participants to reflect and report in their own words, leading to rich, user-driven data. 5.1.4.2 Cultural probe A cultural probe is a method where provocative materials are given to the participants, to help them reach thoughtful self-understanding about their lives, context, thoughts and interactions (Hanington & Martin, 2012). This method is often creative, varied and imaginative. In this method, any kind of material could be given to the participants, for example postcards or disposable cameras, to guide personal responses. The method is not intended to be formally analyzed, but rather to identify key patterns and themes that might emerge. 5.2 Methods of Define phase This section presents the methods used in the Define phase. 5.2.1 KJ-analysis The KJ-method is a method for qualitative data formulation and analysis (Scupin, 1997). Information relevant to the problems is written down on labels and each label contains only one concept, thought or opinion related to the problems. The labels are then grouped into “themes”. Here, biases should not motivate the grouping into themes, rather feelings or intuition. When repeating this process, larger themes will emerge and when all labels have been assigned a team, the team is given a title. The themes can then be grouped into larger “families”, helping to classify the data. When themes and/or families have been created, a chart will start to form by organizing the teams by occurrence and/or via arrows that indicate connections or contradictions. Finally, the chart is explained in writing or verbally, often developing new ideas surrounding the problems. 5.2.2 PEPA PEPA is an analytic assessment method for ergonomics in relation to a specific product (C. Berlin, personal communication, January 29, 2025). With PEPA one can analyze the ergonomics in a specific 21 task related to a critical user, to identify what steps in the task that result in strain on the body. The PEPA-table consists of steps in the task on the X-axis which are established from an HTA. An HTA is a task breakdown method which analyses a task and divides it into sub-steps and subgoals. On the Y- axis there are different ergonomic themes (such as force and precision). The analyzer will then estimate the strain for the critical user to low, medium or high for every step in the task and every ergonomic theme. 5.2.3 REBA REBA (Rapid Entire Body Assessment) is one of the most established methods for analyzing physical strain on the body (Bohgard, et al., 2009). Like the name suggests, this method focuses on the entire body. REBA also takes into consideration coupling effects, if the position of upper extremities is caused by gravity and if large dynamic changes of posture occur. The result from REBA is then connected to categories of action depending on the severity of the position, for example if measures must be taken or if it should be subject to further investigation. 5.2.4 List of requirements A list of requirements is a structured method used to define all the necessary requirements a product must fulfill (Johannesson, Persson, & Pettersson, 2018). The list can be organized into various themes, for example functional requirements. For a specific requirement, it is often described and ranked in priority. Often, the requirement list is divided into requirements and wishes, where wishes do not need to be met for the product to function. 5.3 Methods of Ideate phase In this section the methods of the Ideate phase are presented. 5.3.1 Brainstorming Brainstorming is a method used for idea generation (Johannesson, Persson, & Pettersson, 2018). It is a creative and open method for exploring new ideas and solutions to problems. This method aims to explore as many ideas as possible, where quantity precedes the quality of the solutions. 5.3.2 Brainwriting Brainwriting is a method used to come up with new ideas but is initiated individually and nonverbally (Tague, 2023). Participants write down ideas alone, to then be shared and added upon when a number of ideas have been produced. Brainwriting is used when a large range of ideas are 22 desired, when participation of the whole group is desired, to encourage equal participation and when ideas might be complex and require explanations. 5.3.3 6-3-5 6-3-5 is a creative method used for idea generation (Johannesson, Persson, & Pettersson, 2018). Firstly, all individuals sketch or write down several ideas that differ from each other, for a set time. After a few minutes, the ideas are passed along to the next participant. The timer will then start over, and each participant will be adding ideas to the already written ideas from the previous participant. This is to encourage collaboration and development of ideas. 5.4 Methods of Prototype phase Below the methods of the Prototype phase are presented. 5.4.1 Mock-up Physical mock-ups are an experimental way to test design decisions (Strobl, 2012). The level of fidelity in a physical mock-up can vary. Simple mock-ups can consist of easily obtained materials such as cardboard boxes or tape, where ideas can be quickly tested and manipulated. Simple mock- ups are both less expensive and less time consuming than detailed models. 5.4.2 Rapid prototyping Rapid prototyping is a technique and method for immediate conversion of CAD models into physical prototypes (Kamrani & Abouel Nasr, 2010). It is done through slicing the model into multiple 2D layers and stacking them one layer at a time. This method is often used to reduce the time spent on product development cycles, to quickly assess concepts. 5.4.3 Traditional prototyping Prototyping is a method for exploring, testing and communicating ideas (Bäumer, Stolterman, & Croon Fors, 2018). A traditional prototype is a physical or digital model that presents essential parts of a design. It helps improve communication, learning and decision-making in the design process. Depending on the design phase and the objectives, a prototype can be both high- and low fidelity. 23 5.5 Methods of Evaluate phase Below, the methods of the Evaluate phase are presented. 5.5.1 Concept selection Concept selections are done iteratively in the product development process and can be done in various ways (Ulrich & Eppinger, 2015). It’s a process of narrowing concepts down and eliminating worse performing ones. Concept selection can be more or less structured and follow different methods. Common methods are Intuition, pros and cons, multivoting, or external decision. The concept selection can also be combining several aspects and be a mix of different methods. 5.5.2 Pugh matrix The Pugh matrix is a decision-making tool used to evaluate and rank concepts by comparing them with a reference product (Johannesson, Persson, & Pettersson, 2018). Each concept is assessed based on whether it meets the requirements better (+), worse (-), or equally (0) compared to the reference. The scores are summed up, providing a clear ranking of concepts and identifying those most suitable for further development. 24 Process 25 6 General description and procedure This chapter includes the description of the project model, and its respective phases, on which the project is based. 6.1 Project model Figure 11: Project model The process used in this project is a modification of the design thinking process, a non-linear product development process. This modified process includes five phases, with their respective goals and focus; Empathize, Define, Ideate, Prototype & Evaluate (see Figure 11). The difference from the design thinking process is that Evaluate replaces “Test”. This is done because the evaluation of this project is essential, both in terms of ergonomic comparisons, but also for concept evaluations. This project model was chosen based on several advantages. The design thinking process model places the user at the center, which is suitable for a project focused on ergonomics. This ensures that the final product isn’t just technically sound, but also relevant, desirable and usable for the end user. Furthermore, it provides a structured but flexible framework, applicable to an iterative but goal-oriented project such as this thesis work. It allows for flexibility but also supports exploration without losing focus. This process model is also creative at its core, encouraging ideation beyond obvious solutions through exploration, increasing chances of innovative and meaningful end products. This encouragement also helps balance theory with practicality, for example with user testing and prototyping, further improving validation for real-world solutions, not only theory-based concepts. In this project an iterative workflow is applied to guarantee that input from different phases won't be discarded, considered equally and to its fullest potential. Thus, methods can be repeated and overlap from one phase to another. 26 6.2 Description of phases This section presents the goal, aims and contents of each phase in the order they are presented in the project model. Emphasize The emphasize phase aims to gather knowledge in the area of ergonomics, existing solutions and essential dishwasher functions to ensure a rigid foundation for the project. The aim is also to gather information regarding user needs in dishwasher use, preferences and ergonomic pain points to ensure a fair problem identification (see chapter 8 for the results of the Empathize phase). Define This phase aims to identify the needs and requirements for the end concept(s). This, by analyzing and summarizing the insights from the emphasize phase. With numerical data and qualitative insights, a list of user needs will be produced as a result of this phase (see chapter 9 for the results of the Define phase). Ideate The ideation phase will employ an iterative process with the aim of developing several concepts. The goal of this phase is to produce several ideas and solutions to the problems identified in the previous phase, it aims to refine ideas into concepts, and it also aims to try out ideas, discard, combine and develop iteratively against the list of user needs. This is to ensure that nothing important from the previous phase is missed and that all possibilities are explored (see chapter 10 for the results of the Ideate, Prototype and Evaluate phases). Prototype This phase aims to create solutions physically and thereby test ideas from the previous phases. By the end of this phase a better idea of the solutions’ possibilities and limitations will be obtained, benefiting potential real-world implementation (see chapter 10 for the results of the Ideate, Prototype and Evaluate phases). Evaluate In the last phase, the concepts will be evaluated to know which concept to further develop and to validate the chosen concept. This phase is iterative and is present along with other phases. The aim 27 of the evaluation phase is to ensure that and investigate if the concepts meet the list of user needs set from previous phases, mainly in terms of ergonomic improvements (see chapter 10 for the results of the Ideate, Prototype and Evaluate phases). 28 7 Project execution Below, the execution of the different phases in this project will be presented, using the phases explained previously as a guide. The project execution is presented in a chronological order and since the development process is iterative, some of the phases are explained together as they overlap. 7.1 Execution of Empathize phase This section presents how the Empathize phase was executed, including pre-studies and user studies (see chapter 8 for the results of the Empathize phase). 7.1.1 Online and literature research The project began with online and literature research to obtain knowledge of the current situation of ergonomics in dishwashers, how to best perform ergonomic assessments as well as carry out analyses of competitors ergonomic solutions. Databases that were used during this research phase were Chalmers library and AcessSience. Search engines such as Google Scholar was also used with search words such as “Ergonomic solutions in home appliances” and “Design solutions for dishwashers”. The aim was to find research on, and public solutions to similar ergonomic challenges, as well as dishwashers and the functions of these. Furthermore, the literature research also included gathering information on specific ergonomic assessment tools and methods from other studies and articles on ergonomics. The goal of this was to map out aspects of ergonomic issues to consider, as well as to get an understanding of the current solutions on the market. 7.1.2 Site visit and self-test After finishing the online and literature research, a field trip to two showrooms was scheduled, to see some of the competitors’ solutions firsthand. One showroom exhibited an Electrolux Comfort- Lift, designed to raise the lower basket to a more comfortable working height. The lower basket is lifted with the help of a handle that unlocks the basket and spring that helps elevate the lower basket to the height of the upper basket. This, however, hinders the user from using the upper basket simultaneously and blocks the user from refilling salt. The other showroom exhibited a Fisher & Paykel divided drawer dishwasher, that is designed for the purpose of making dishwashing more sustainable, running one of the two drawers at a time if the amount of dishware is lower than a full load. However, the design for sustainability in the Fisher & Paykel dishwasher is also beneficial for ergonomics, especially for the higher drawer. These two dishwashers were briefly examined mechanically, functionally and during the task of opening and pulling out the drawers to obtain an understanding of function, usability and ergonomic benefits. 29 7.1.3 Functional analysis To ensure understanding of the different functions and sub-functions of a dishwasher a functional analysis was made. This was done with the knowledge attained from ASKO, combined with the information gathered from literature and online research. 7.1.4 Product breakdown A product breakdown was carried out to get a better understanding of the different parts of the dishwasher relevant for the project. Two pictures of an ASKO dishwasher were used for labeling different parts of the dishwasher, one of a front view, and one of an exploded view. Information needed to label the different parts was obtained from the ASKO webpage. 7.1.5 Expert interviews Semi-structured interviews were held, focusing on two professional categories: Ergonomic experts, such as physiotherapists, and dishwasher experts, such as kitchen architects. These interviews were held with the aim of creating a rigid knowledge base in these areas. All interviews were recorded and transcribed using Words’ transcription tool. The transcribed material was then read through, and interesting opinions and experiences were marked, to be sorted into a KJ-analysis at a later stage. 7.1.5.1 Interview ergonomic experts Two interviews were held around ergonomics. One interview with a physiotherapist and one with an occupational therapist. For these interviews an interview guide was created (see Appendix 1: Interview guides). During the interviews the interview guide was followed but with space for follow up questions, probing and skipping questions already answered previously. Themes such as working posture during dishwasher use, common user errors, bodily strain and possible improvements of dishwashers were discussed. The interview with the physiotherapist was held in an online meeting, lasting for about 30 minutes. The interview with the occupational therapist was held at their workplace, lasting for about 30 minutes. 7.1.5.2 Interview dishwasher experts Two interviews were held around dishwashers. One with a kitchen architect and one with a kitchen appliance and dishwasher expert. For these interviews an interview guide was created similarly to the interviews with the ergonomic experts and the interviews were conducted in a similar way (see Appendix 1: Interview guides). However, the focus for the interviews with the dishwasher experts 30 were functionality, customer opinion, surrounding structure in the kitchen area and broader questions around ergonomics such as other ergonomic solutions in the home. 7.1.6 Letters Since the method Letters is a combination of different methods, the process of forming the method began with a meeting with a lecturer within design and human factors to discuss aims, methodology outline and layout. Once these aspects were established, the creation of the layout of the letters began, resulting in five letters. Each letter was based on different themes for the participant to fill out. The letters were created in Figma and were later labeled with day 1 through day 5 (see examples in Figure 12). All the letters can be viewed in Appendix 2: Letters. These letters were created for the purpose of obtaining deeper thoughts and experiences from the users regarding their lifetimes with their dishwashers. To do this, each letter has probing attributes and asks of the users to see themselves in different scenarios, and to write letters for different purposes. Figure 12: Letters A pilot study was performed to establish the final layout of the letters as well as the contents to ensure that the information that was needed for the study was obtained. The pilot study was carried out with two participants. The pilot study had a duration of 4 days, and the filled-out letters were then analyzed regarding information gathered, which resulted in some changes in the final layout, such as changing the introduction of some of the letters to target specific information and rephrasing some questions for the same purpose. 31 The letter for day 1 was a “love letter”, where the participants were asked to describe what they like about their dishwasher. The letter for day 2 was a “hate letter”, where the participants were asked to describe what they dislike about their dishwasher. The letter for day 3 was a “letter to your physiotherapist” where the participants got to fill out where on the body they experience the most strain while using their dishwasher, what the hardest thing is when using their dishwasher and how much they had loaded or unloaded their dishwasher that specific day, in relation to how much strain they experienced in the body. The letter for day 4 was an “excerpt from my diary” where the participants got to fill in a timeline explaining about times in their life where it was especially difficult to use their dishwasher, when the dishwasher potentially broke down or when they saw someone else having a difficult time when using the dishwasher. The fifth and last letter was a “letter to Santa” where the participants were asked to describe their dream dishwasher, with no limitations. They were also able to add to their description with drawings. These five letters were packaged in envelopes corresponding to each of the five days and they also came with an introduction (see Figure 13). Figure 13: Letters in envelopes 32 The introduction thanked the participant for participating in the study and included an explanation of the context of the study in connection with this master thesis. It also explained the purpose of the study and that it was designed the way it was to allow them to reflect from different viewpoints. Furthermore, the introduction also encouraged them to open the letter in the morning, reflect during the day and answer in the afternoon or evening. The letters were sent out to seven participants, aged approximately 40-80 years old with 5 women and 2 men, to be filled out in one week’s time (see Figure 14). These participants were chosen based on their age (preferably over 30 years old to have some longer experience with dishwashers) , and that they owned a dishwasher. To minimize potential bias from the participants, they were selected via indirect social connections, such as extended family acquaintances or friends-of- friends, rather than individuals with close personal ties with the authors. Figure 14: Participant selection Letters After one week, the letters from the participants were collected, read and answers interesting for the study were marked and then categorized in a KJ-analysis. 7.1.7 User test A pilot study was first performed for the user test to ensure that the information needed was obtained. The pilot study was carried out with one participant and one ergonomic researcher that observed the implementation of the test to later give feedback. The pilot study resulted in a few changes to the real user tests, such as filling the dishwasher half-full of dishware to guide the user on where to place dishes and to resemble a real situation. Six user tests were conducted with three women and three men, ages ranging from 50-64 and heights from 161-185 cm (see Figure 15). These participants had been chosen based on their age (50+ to get input from users with longer experience with dishwashers), their height (to ensure representation of different heights in the study) and to preferably not have a background in ergonomics or product development (to not be colored by their previous knowledge). The selection of participants was carried out through contacting the Chalmers library and Chalmers administration and sending an open invite, and by contacting lecturers at Chalmers and asking if they wanted to participate. 33 Figure 15: Participant selection User test The user tests were carried out to get physical observations on the use of the dishwashers to later be able to conduct ergonomic assessments. The participants were invited to a 40-minute test where they were to use dishwashers and “think out loud” while doing so. The test procedure looked like this: 1. Open and load a dishwasher with the dishware available on the table 2. Add the dishwasher detergent and close the door 3. Open and unload the dishwasher and put the dishware on the table 4. Answer the first part of the survey 5. Open and load another dishwasher with the dishware available on the table 6. Add the dishwasher detergent and close the door 7. Open and unload the dishwasher and put the dishware on the table 8. Answer the second part of the survey 9. Final questions and short discussion To ensure that the tests could be completed, the set-up included two dishwashers, one ASKO dishwasher on floor height, and one Gorenje dishwasher that was raised 35 cm of the floor using three EU pallets. The reason for having one raised dishwasher was because the information gathered from the literature and interviews pointed to that raising the height of the dishwasher could be beneficial for the users’ work position. The participants also had dishware to be able to load and unload the dishwasher. To be able to analyze the participants’ work position during the tasks, the test was recorded with video and audio using two Go-Pros placed at two different angles. In the middle and at the end the participants filled in a survey regarding how they rated the strain on the body during each task on each dishwasher on a scale from 1-6, 1 being “not straining at all” and 6 being “very straining”. At the end of the survey the participants answered which one of the two dishwashers was the most straining overall. The test ended with a discussion regarding the overall feeling during the test and final thoughts. Only the audio was recorded for this part. When the 6 tests were completed, all film and audio material were reviewed and notes were taken on observations regarding user behavior, work positions and the comments that the participants made during and after the test. The comments that the participants made during the tests and the Technical profession 34 final discussions were sorted into a KJ-analysis at a later stage. The film material was reviewed once more to conduct ergonomic assessments. 7.2 Execution of Define phase This section presents how the Define phase was executed, including ergonomic assessments and KJ- analyses (see chapter 9 for the results of the Define phase). 7.2.1 Ergonomic assessments Ergonomic assessments were conducted to identify problematic areas within the tasks completed during the user tests. The methods used for this assessment were PEPA and REBA. PEPA was used to analytically identify ergonomic pain points in specific steps of the tasks, based on how the user handled the dishwasher. Thereafter, REBA was used to gather numeric data that would provide a ranked score accompanied by a suggestion of action. The REBA score would also enable a numeric comparison in the final evaluation. The combination of these ergonomic assessments reinforced the validation of the project outcome. 7.2.1.1 PEPA The method PEPA was created for assessing ergonomics for a critical user. However, in the user tests three critical users were identified and therefore selected. The critical users chosen were the tallest, the shortest and one participant with scoliosis. Firstly, the video and audio materials were observed and analyzed, and an HTA was conducted to break down the steps of the task performed by the users. Thereafter, each step was observed, discussed, and finally evaluated on the scale “low physical effort, medium physical effort, or high physical effort”. To further understand the result, the complete tables were imported into Figma and further analyzed with comments, pictures and connections. Problems were grouped into themes to be a part of the merged KJ-analysis. 7.2.1.2 REBA REBA was conducted on the most critical ergonomic positions found in the video materials and on positions frequently repeated among the participants. Each video was observed through two angles and paused where a critical position was observed. These still images were saved and later analyzed through a REBA worksheet. Among the most critical ergonomic positions observed, deep bends were one of the most prominent positional issues among the participants, meaning that this position was a focus point in the REBA worksheets. This position was also compared between the two dishwashers used in the 35 user test. Lastly, raised shoulders, arms, positioning of legs/knees, neck extensions and twists of wrists were also observed. 7.2.2 KJ-analysis The data from each study (interviews, letters, and user tests) was analyzed first separately, grouping common comments, quotes and observations together, into common themes and themes within themes. Then a merged KJ-analysis was created to understand the overall themes and what has been observed and mentioned in more than one study. When the merged KJ analysis was done, connections between different themes were analyzed. The connections between the themes were drawn with dashed arrows, one-sided arrows and interconnected arrows, to separate the connections of something that could be a solution to a problem, something affecting something, and to themes affecting each other. From the data in the merged KJ-analysis as well as the connection between these, the categories and themes were translated into user needs. 7.2.3 List of user needs The list of user needs created in this study was based on the data obtained from the merged KJ- analysis. The list was designed as a requirement list but does not include target values and hard values. The list is more focused on soft values within the user needs and wishes collected in the previous phase. The reason for the creation of the list of user needs was to be able to structure and highlight some of the large number of needs gathered throughout the study, and to be able to use as a basis for later decision making in the development process. The user needs were divided into needs and sub-needs. The needs stemmed from the larger common themes in the hierarchy of the KJ-analysis as well as the number of connections that had emerged for them. The sub-requirements stemmed from the smaller themes and opinions in the hierarchy and specified and defined the needs. The list was divided into functional, emotional, ergonomic and other requirements. 7.3 Execution of Ideate, prototype and evaluate phases This section presents how the Ideate, Prototype and Evaluate phases were executed, including Ideation, prototyping and decision-making. Since these phases are iterative and overlap, the execution of them is presented together. This is to ensure a presentation of the execution that mirrors the true order in which it was done (see chapter 10 for the results of the Ideate, Prototype and Evaluate phases). 36 7.3.1 Ideation During the ideation methods were used iteratively: Brainwriting, brainstorming and 6-3-5. The brainwriting and brainstorming sessions varied in being conducted individually and as a team. Furthermore, sketches, refinements and mockups were also made in an iterative manner, whereas sketching and refinements also varied in being conducted individually and as a team. Additionally, some of the sketches were also refined and visualized with higher fidelity using AI, for example by adding materials. Lastly, mockups were created. The ideation started with brainstorming and brainwriting individually with the goal of producing as many ideas as possible (see Figure 16). Ideas varied in visuality, some being text, rough sketches, provisional sketches, and inspiration in combination with explanations. The individual ideation lasted for a few days, resulting in many ideas. These ideas were then brought forth in a discussion, where similar ideas were grouped together and thoughts, opinions and ideas of improvement were shared, and some ideas were developed further as a part of the brainwriting process. Figure 16: Ideation When all ideas had been grouped and discussions had been held, a round of 6-3-5 was conducted. This was carried out in three rounds with three different groups of concepts of interest. The aim of using this method was to further add on to the number of ideas. A discussion was held after these 37 sessions and advantages, problems and unclarities regarding the ideas were raised. Thereafter, a list was made on possible further refinements of ideas as well as points of investigation, especially regarding mechanics and realizations. Different mechanical solutions on the market were investigated and knowledge was gathered to be able to refine some of the concepts. After some refinements were made a discussion regarding the concepts was held with ASKO, where some concepts proved to be more interesting and feasible than others, subsequently eliminating a few concepts in a concept selection session. The concept selection that followed these discussions was based on both the discussed requirements and on intuition regarding the concepts overall potential. Furthermore, an external engineer with long experience in mechanics was also asked to take part in a discussion regarding how to realize these concepts, giving even more insight into possible construction plans. When having ideated, explored feasibility and discussed with ASKO and the engineer, mockups were made on a few of the concepts that moved forward from the concept selection. The mockups were made to further understand and explore mechanics and how the concepts would work in the real world. This was done iteratively; creating mockups; sketching on a new variant; changing the mockup; gathering information to solve problems found; changing the mockups again. Another discussion about the concepts was then held once more with ASKO. The aim of this discussion was to eliminate concepts that were not feasible and to obtain construction suggestions of prototypes for these concepts. When the mockups were made, mechanics were sufficiently understood, and the concepts were on the same level of fidelity another selection had to be made. The aim of this selection was to evaluate the concepts against the list of user needs and as a result eliminate concepts accordingly. 7.3.2 Pugh matrix To decide what concepts to continue with in the ideation phase, a Pugh matrix was created, with the user needs on the Y-axis and the concepts on the X-axis. Each concept was discussed against each of the user needs and scored either 0, if equal to the current ASKO dishwasher, “+” if it performed better, “- “if worse, and “?” if more investigation was needed to say. Each of the “+” were added and all the “- “ were subtracted from the total. As a result of the Pugh matrix some concepts could be eliminated based on their score, leaving four concepts. However, more information was needed on a few of the concepts that had the same score but had “?” on some user needs. Therefore, two of the concepts were rapid prototyped to more fairly be compared in the table. Thereafter the summarization of the scores were updated again and decisions about what to further develop were made. 38 7.3.3 Rapid prototypes When decisions were made based on the Pugh matrix, prototyping was initiated for three concepts. The aim of the prototyping was to test the functions, size and measurements and get an understanding of what it would look like in reality, to later be able to make decisions on what to further develop. Catia V5 was used to model the prototypes and their respective parts. The parts were later exported as STL files and imported into PrusaSlicer to be positioned and sliced as preparation for 3D-printing. The prototypes were then 3D-printed and assembled. With the functional prototypes, function, mechanics and strain on different components of the concepts could be investigated and based on these findings, decisions could be made regarding what concept to move forward with. It was decided to combine three of the four remaining concepts, while also developing the fourth concept separately, resulting in two separate tracks for the final concept; A scissors lift concept and a modular baskets concept. 7.3.4 CAD When the final concept had been chosen, modeling in Catia V5 was initiated for the final concept. The starting point of the modeling was a current ASKO dishwasher model. This model was used as reference and as a base for building the new parts. The final CAD file was then exported into VRED for final renderings and animations. 7.3.5 Visual prototype Based on the CAD model of the scissors lift concept, a non-functional prototype in real scale was created. The goal of this prototype was to be able to execute ergonomic assessments on the concept, hence the prototype being created in 1:1 scale. To simplify and to be able to build it within the time frame, a decision was made to build it in a static position. Firstly, the prototype was built using pine wood sticks and thin wooden sheets as a separate platform from the dishwasher, designed to be placed on top of the dishwasher door. In this prototype, the measurements of the height of the platform matched the measurements of the CAD model in the lifted position. But the width and length were over dimensioned, as well as the size of the scissor’s arms, since the height was what mattered the most for the execution of the ergonomic assessment. To build the prototype, a band saw was used to cut the wooden parts to the correct size, and a drill, screwdriver and screws were used to attach the wooden sticks to the wooden sheet (see Figure 17 for a picture of the process). 39 Figure 17: Process of first prototype A decision was made to further refine the prototype and build it more closely to how the real product would look like. Similarly to the first prototype, this was built as a non-functional static prototype. In this final prototype, an inner dishwasher door was used as the upper platform, and 2 mm thick 25 mm wide aluminum flat profile lists were used as the scissor’s arms. Since the aluminum profiles were a bit too unsteady, the profiles were stacked with two profiles, attached with double-sided tape, resulting in a thickness of 4mm. To attach the scissors lifts arms to the upper inner dishwasher door, 90-degree angled aluminum profiles were attached and bolted to the bottom of the inner dishwasher door. At the lower inner dishwasher door, attached to the machine, the arms were screwed directly into the steel. Before bolting, the holes were measured and predrilled. When the scissors arms and upper platform were mounted, the prototype was unsteady in the X- direction. Therefore, an extra 90-degree aluminum profile was mounted between the back of the upper platform and into the dishwasher, to minimize movement. Additionally, the modular basket concept was also prototyped, but with lower fidelity with the goal of testing size and weight (see Figure 18 and Figure 19). 40 Figure 18: Modular basket prototype for plates Figure 19: Modular basket prototype for cups and glasses These prototypes were created with already existing basket inserts with rods from another basket mounted on, to be able to place plates, cups and glasses and test the weight, size and stability. 7.3.6 Visualization of modular baskets The modular basket concept was further visualized using Figma. Pictures from ASKO dishwashers were used as a base, edited with lines to sketch and present the concept of the modularity. A decision was made to not refine the visualizations further and leave it as a theoretical concept that could be combined with the scissors lift concept and as a subject for future work. 41 7.3.7 Ergonomic assessment REBA With the refined static visual prototype of the scissors lift concept, pictures were taken to be analyzed with REBA. Since the limited time frame of the project, and the similarity to the raised dishwasher in the user tests, it was decided to not evaluate through a second user test, but to carry out self-tests for evaluation and validation purposes. 42 Results 43 8 Results of Emphasize phase This chapter presents the results of the empathize phase, including results from pre-studies as well as the results from user studies. 8.1 Functional analysis The results from the functional analysis are presented in a tree-diagram, presenting the main, sub and other functions (see Figure 20). Figure 20: Functional analysis The main function is “Wash dishes automatically” and this function is divided into “Clean dishware automatically and “Dry dishware automatically”. Furthermore, “Clean dishware automatically” is divided into “prepare for washing”, “perform washing” and “manage waste”. 8.2 Product breakdown The product breakdown is presented in two separate views, one of which parts can be seen from the front view picture, and one from the exploded view picture. The most important parts of the dishwasher for this project are viewed (see Figure 21 and Figure 22). 44 Figure 21: Product breakdown of dishwasher A6 Figure 22: Product breakdown of dishwasher B7 6 Picture published with permission from ASKO. Retrieved from ASKO (https://se.asko.com/produkter/kok/alla- diskmaskiner/fullintegrerade-diskmaskiner/DISHWASH-DW60-2-DFI544H-1-ASK/p/000000000000746022), edited by the authors. 7 Picture published with permission from ASKO. Retrieved from ASKO (https://se.asko.com/kok/diskmaskiner/funktioner), edited by the authors. 45 8.3 Interviews results The interviews resulted in two separate KJ-analyses, one for the ergonomic experts and one for the dishwasher experts. The KJ-analyses were done separately since the interview guides differed from each other. 8.3.1 Interviews ergonomic experts results The KJ analysis from the interviews with the ergonomic experts resulted in several themes and themes within themes (see Figure 23). Figure 23: KJ-analysis Ergonomic Expert Interview A few of the bigger themes were Working height, Grip & hand strength, Back & bends, Critical users and Balance. See Appendix 5: KJ-analysis themes for a complete account for all the themes. 46 From these interviews the general opinion was that the back is subjected to the most strain while loading and unloading the dishwasher and that the cause of this is an unfavorable working height and heavy lifts. Grip and hand strength were also important topics, where some tasks when using the dishwasher, such as opening the lid for detergent or gripping dishware, were especially straining. In these interviews critical users were also discussed, such as the elderly. These users would also have issues with balance when performing dishwasher related tasks. This is because of the low working height, deep bends and moving the center of gravity over the lower basket, trying to avoid hitting the dishwasher door and reaching the dishware. Additionally, robustness, space in and outside of the dishwasher, repetitive work and adjustment and adaptation were also discussed. 8.3.2 Interviews dishwasher experts results The material from the interviews with the dishwasher experts was handled in the same way as the interviews with the ergonomic experts. Interesting opinions and experiences from the interviews were sorted into a KJ-analysis and several themes emerged, see Figure 24. Figure 24: KJ-analysis: Dishwasher Expert interview The biggest themes that emerged were for example High installation, Comfort Lift, Pulling out the lower basket, Modular baskets & inserts and smart functions. See Appendix 5: KJ-analysis themes for a complete account for all the themes. 47 In these interviews the most prominent opinions were regarding high installation, where it was agreed upon that dishwashers should be prioritized when raising appliances in the kitchen, since the dishwasher is used more often. Pulling out the lower basket and for it not to derail and run smoothly was also a reoccurring theme, where a derailing lower basket could potentially cause both frustration, pain and injury, especially because it’s located at a very low height. Benefits and problems with the Electrolux Comfort Lift were also discussed, for example, that it provides a good working height, but it obstructs the use of the upper basket, forcing the user to only use one basket at a time. Modularity was also a topic where both benefits and problems arose. Many customers like modularity and it could improve the ergonomics, but if it becomes too modular, it becomes hard and troublesome to use and understand the dishwasher functions. Customers typically want something that is easy to use and that can be trusted for a long period of time, they do not want to read through the instructions a second time. Additionally smart functions, accessibility and the elderly were discussed. 8.4 Letters results All letters were received from the participants about 2 weeks after they were sent out. The letters were opened, read through and interesting opinions and experiences were marked (see Figure 25 for examples of the filled in letters). Figure 25: Results Letters The marked quotes from the letters were then categorized in a KJ-analysis where themes and themes within themes emerged (see Figure 26). 48 Figure 26: KJ analysis Letters From the KJ-analysis several themes emerged, a few of the biggest were User friendliness, Quality, Body, Base requirements and Packing. See Appendix 5: KJ-analysis themes for a complete account for all the themes and sub-themes. From the letters it became evident that quality was one of the most important aspects for the users when it comes to dishwashers. Many of the issues explained in the letters were regarding the dishwasher breaking, baskets derailing displays getting fainter with time etc. The second largest theme from the letters was “body”. This theme is connected to the ergonomics of using a dishwasher. Many of the respondents explained that lumbago is a common issue when using the dishwasher, and that it stems from deep bends and repetitive work on a low working height. Some also explained that they would like to have the dishwasher at a better working height, especially the lower basket. Fingers and hands were also an issue for some respondents, where pain arose from broken handles or when grabbing dishware. Another important theme was “packing” where effective packing was largely discussed, the users want it to go as fast as possible when loading and unloading the dishwasher. Additionally, some base requirements were mentioned such as running quietly and cleaning thoroughly. 8.5 Summary of Results of Empathize phase To summarize, the empathize phase resulted in a breakdown of the dishwashers’ various functions, a breakdown of its different components, as well as grouped recurring themes from both interviews and the Letters method. Key insights from this phase revealed that deep bends, grip and critical users are important factors when designing for ergonomic improvements. Moreover, insights regarding higher installations, robustness and existing ergonomic home appliance solutions emerged as recurring themes. 49 9 Results of Define phase This chapter presents the results of the Define phase, including ergonomic assessments and KJ- analyses. 9.1 PEPA results From the PEPAs one could observe what steps during the use of a dishwasher were the most straining and what ergonomic issue was the root of the problem. One could also observe the difference in strain in each step between the dishwasher on floor-height and the raised dishwasher (see Appendix 8: PEPA for all PEPAs). The dishwasher on floor height demonstrated several issues, mostly regarding steps in relation to loading and unloading the dishwasher. Parts of the body most affected by this activity were the back for all participants, in combination with endurance when being in a bent position for a longer period. The PEPA also demonstrated instances of strain on legs and knees, in connection with trying to reach the lower basket. Furthermore, precision work, such as loading cutlery, was also on a higher level of strain, this was because the hit area was less than 10 millimeters (see Figure 27 for one PEPA on a dishwasher on floor height). Figure 27: PEPA TP3, Floor height 50 In this PEPA one can also view examples of positions that result in the yellow or red fields, such as bending down and bending both the knees and the back. The PEPAs made for the raised dishwasher demonstrated overall lower strain on more fields in comparison to the PEPAs for the dishwasher on floor height (see Figure 28 for a PEPA on a raised dishwasher). Figure 28: PEPA TP3, raised height Here, the strain on the back, knees, legs and neck was much lower because of the raised height. This was true for all the participants. The yellow and red fields at the top in this PEPA represent precision work such as placing plates and cutlery on a small area. The precision work is generally the same for both dishwashers. However, there is one field for “opening the door” and “grip” that is red. The reason for this is that the participant didn’t see the handle, opening the door with force from the side, therefore there is also a yellow field for the same step but for “fingers” as well. When comparing these two PEPAs one can observe that the PEPA for the raised dishwasher received about ten fields less than the PEPA for the dishwasher on floor height. Meaning that the raised dishwasher resulted in less strain overall. One could also observe that the most straining 51 steps in the sequence for the dishwasher on floor height, with four yellow fields, were step 4 and 10, loading dishware in the lower basket and unloading dishware from the lower basket (see Figure 29). Figure 29: PEPA, Floor height, most straining steps Other straining steps with more than one yellow field were: Step 2. Pull out lower basket Step 5 Load upper basket Step 6 Load cutlery Step 7 Load detergent Step 11. Unload cutlery All the steps above except step 6 have issues when it comes to bending the back, meaning that bending the back could be a relevant problem area to work with. The precision work received both yellow and red fields on several steps in both PEPAs, meaning that this also could be a relevant field to work with. 52 From the PEPAs it could be observed that the raised dishwasher had fewer ergonomic issues in the different steps, however, there was a concern regarding shoulders for shorter people when handling the cutlery basket, since the entirety of the dishwasher was raised during the tests. As can be observed in Figure 30 the participant experiences raised shoulders, and raised upper arms, which was also commented on during the test, which are negative effects of raising the entirety of the dishwasher. Figure 30: PEPA TP5, raised height 53 9.2 REBA Result Figure 31: Reba worksheet Fifteen REBAs were conducted. REBAs were conducted on all participants, at least two for each one. In Figure 31, an example of a filled in REBA worksheet can be viewed. The focus for the REBAs was the deepest bend on both the raised dishwasher and the dishwasher on floor height. The reason for this was that bending down was seen as the most problematic position in the PEPAs. Precision was also seen as a problem in the PEPAs, therefore some of the pictures taken to be included in the REBAs were a combination between precision work and bending down. Lastly, some extra REBAs were done on other awkward positions. In this section, still frames of some of the positions used in the REBAs will be presented and the belonging worksheet can be found in Appendix 7: REBA. 54 Figure 32: REBA 1 This first REBA (see Figure 32) is during the task of opening the door and about to pull out the lower basket on the dishwasher on floor height. This position received an overall score of 5, meaning medium risk. In this position, the trunk received the most points because of the deep bend. This bend also results in bending of the legs, resulting in extra points for legs as well. Furthermore, upper arms, lower arms and wrist also received points, but not as high as trunk, but these also stem from trying to reach down, extending arms for example. Figure 33: REBA 2 55 This second REBA (see Figure 33) is during unloading of the lower basket on the raised dishwasher. This position received 3 points, meaning low risk. A clear improvement from the previous REBA. The main reason for this is that the bend isn’t as deep. This means that both trunk and legs received lower points. One can also observe that points for extension of the upper arm are lower, which also is a result of the less deep bend and better reachability. Other points in this position are also overall low, but this position received two extra points for actions that result in large change movements and small change movements. Meaning that the participant is both grabbing several plates (small change movements) and moving away from the dishwasher to place them on a table (large change movements). The points were generally higher for the dishwasher on floor height and lower for the raised dishwasher, however there were some instances where both received the same points (see Figure 34 and Figure 35) Figure 34: REBA 3 In this instance (see Figure 34) the position that affects the points the most is once again the trunk, but not the legs. This is because this participant is shorter, meaning that they don’t need to bend down as low as the previous participant, and therefore bends the legs a lower degree, resulting in lower points. However, this participant receives similar points as the previous participant when it 56 comes to upper and lower arms, again because they are trying to reach down, extending the arms. This participant also receives higher points on flexed and twisted wrist when grabbing an oven dish as well as points for large and small change movements. Figure 35: REBA 4 When this participant uses the raised dishwasher (see Figure 35) they receive lower points for the trunk, but higher points for the neck and legs. The reason for the higher points for the neck is that it’s twisted to be able to look into the dishwasher. Why it is twisted in this instance is because the participant hasn’t pulled out the lower basket completely, resulting in lower visibility and reachability, a frequently observed problem in the user tests. The higher points for the legs are because this participant is leaning on one leg, leaning over to again be able to look into the dishwasher. Points for twisted and flexed wrist are also given here, as well as points for large and small change movements. After doing the ergonomic assessments on the user tests it was evident that the activity of loading and unloading the lower basket was the biggest issue. This results in deep bends, affecting the back, legs and extension of arms. It was also evident that twisted and flexed wrists were issues in these activities, as well as small and large change movements and precision issues when handling dishware. Another observed problem was that the participants didn’t pull out the basket fully, resulting in awkward positions when trying to see and reach. 57 These issues would be even more prominent in some cases (see Figure 36 and Figure 37). Figure 36: REBA 5 In this case the participant sits down on their knees to load the lower basket on the dishwasher on floor height (see Figure 36). The reason for this is that this person has scoliosis and experience issues when bending down and staying in that position for longer periods of time. This demonstrates an important example of how people with different abilities approach the standard dishwasher on floor height. This position also creates new problems for the knees when standing on a hard surface such as the kitchen floor. 58 Figure 37: REBA 6 In this position one can observe an awkward position of the arm, wrist and a pinch grip (see Figure 37). This results in higher points for the upper arm, lower arm and wrist. Here, points for large and small change movements are also obtained. One thing also observed during the tests is that all participants grab several plates at the same time when unloading the dishwasher, resulting in uncomfortable grips. With the problematic steps observed in the PEPAs in combination with the issues in working position observed in the REBAs, it could be determined that loading and unloading the lower basket were the biggest issues. Therefore, the focus forward was to try to minimize the deep bend and repetition of the bend to reach the lower basket. From the points received in the REBA it was also of interest to minimize small and large change movements, increase reachability and visibility to avoid awkward positions, improve grip when handling dishware and minimize precision work in these steps (steps 4 & 10 in the PEPA). 9.3 Questionnaire The participants also answered a questionnaire during the user test. The questions were mainly focused on rating the level of strain after using each of the dishwashers. For example, the participants were asked to rate the strain they felt while unloading the lower basket from a scale on 1-6, 1 being no strain and 6 being high strain (see Figure 38 and Figure 39). (For complete review of all questionnaire answers, see Appendix 4: Questionnaire answers). 59 Figure 38: Questionnaire answers for loading the lower basket on the dishwasher on floor height Figure 39: Questionnaire answers for loading the lower basket on the raised dishwasher As can be viewed from the participants’ answers, the dishwasher on floor level received higher ratings than the raised dishwasher, with as high as 6 points, suggesting uncomfortable and straining positions. At the end of the questionnaire the participants were asked which one of the two dishwashers they felt was more straining and 100% answered that the dishwasher on floor height was the more straining. 100% also answered that it was in the lower back that they felt most strain, with quotes such as “the back quickly became statically loaded, unpleasant working position”. 9.4 KJ analysis User test To ensure that the participants’ opinions and comments in the user test were a part of the analysis, a KJ-analysis was created for this purpose. In this KJ-analysis the observational notes taken from the 60 video material were also included as well as some of the still frame pictures taken for the ergonomic assessments (see Figure 40). Figure 40: KJ analysis User test Several themes and themes within themes emerged in this KJ-analysis, the biggest themes being Layout & space, Taking several things at once, Hassle and fuss, Cutlery basket, Deep bends, Dishwasher on floor (bad) and Raised dishwasher (good). See Appendix 5: KJ-analysis themes for a complete account for all the themes and sub-themes. The comments and observational notes from the user tests showed a large consensus among the participants that the dishwasher on floor height felt worse ergonomically than the raised dishwasher. In connection to this, the participants mentioned lumbago and general pain and discomfort in the back as the biggest issues while using the dishwasher on floor height, because of repeated deep bends and holding the deep bends for a period of time. This was improved by a large extent in the raised dishwasher, where no pain or discomfort in the back was expressed. Layout & space was also an important topic where the participants stressed the importance of a good overview, organized baskets, space for pots and pans and an understandable layout. In the user tests it was also observed what the results were when the layout or functions were unclear: When the users were trying to make everything fit in the baskets they were forced to stay in uncomfortable positions for longer periods of time, especially when loading the lower basket. When forced into these uncomfortable positions frustration also arose. This frustration also led to some compensatory behavior, such as sitting down on the floor to get a better view and reach of the lower basket. Furthermore, there were other user behaviors that became prominent in the user tests. For example, many participants missed the cutlery basket, or just didn’t find it. This resulted 61 in awkward positions when trying to find the cutlery basket. The participants also didn’t pull out the baskets fully. This was a behavior that was repeated among every participant. This resulted in the participants themselves limiting their reachability and forcing themselves into awkward positions, especially when loading and unloading the lower basket. It was also evident that all participants wanted the loading and unloading of the dishwasher to go fast. Therefore, all participants took several things at the same time. For example, several plates were grabbed at the same time in the process of unloading the dishwasher, resulting in non-ergonomic grips and wrist positions that could have been avoided if the participants took one plate at a time, or if the plates had better grip possibilities. Additionally, themes such as an upright position, the dishwasher door and flexibility were also mentioned during these tests. 9.5 Merged KJ To analyze all gathered data from the user studies a merged KJ-analysis was created (see Figure 41). Figure 41: Merged KJ This KJ-analysis includes what was said during the interviews, what was said during the user tests, the observations and the user responses from the letters. Larger circles represent larger themes which include smaller circles that represent smaller themes and there are also smaller titles that do not create an independent theme, but a category within a larger theme. In this KJ-analysis pictures from the user tests and notes from PEPA and REBA are also included. 62 The larger themes with the larger number of opinions and sub-themes were Body load, Raised dishwasher, Compensatory behavior, Behavior & feelings / Cognitive and Functions. See Appendix 5: KJ-analysis themes for a complete account for all the themes and sub-themes. In the merged KJ it became evident what the users expect, want and need in regard to both general wishes such as quality, but mainly regarding ergonomics. Through the merged KJ repeated opinions and observations throughout the user studies could be viewed in a larger context. From all opinions and observations, the most common points were back-related, such as pain in the back, lumbago, deep bends and praise regarding a raised dishwasher or higher installation. This appeared across all studies conducted. Other themes related to the body that became larger themes in the merged KJ were fingers, hands & grip and critical users. In the merged KJ there were also repeated opinions and observations regarding cognitive and emotional aspects, such as wanting to feel effective or not pulling out the baskets fully, risking worse ergonomic working positions. Layout & space and quality & robustness were also largely important aspects across all studies, where layout & space goes hand in hand with wanting to feel effective and aligning with other cognitive aspects such as understanding functions or the interior of the dishwasher. Quality and robustness point to the user wanting to have the same dishwasher for a long time and they want it to look and feel like it is of high quality, which also is a criterion for them to be able to trust the functionalities of the dishwasher. Since the merged KJ-analysis was rather big and had low readability, it was decided to ensure the understanding of the themes through a mapping of them and their connections to each other (see Figure 42). There were three different kinds of connections in this mapping; Solution, a dashed line; leads to, a line with one arrow; and affects each other, a line with two arrows one on each side. From the number of connections and number of opinions in each theme, the first base-themes emerged, later translating to the user needs. Figure 42: Merged KJ Connections 63 The base themes that came from the connections mapping of the merged KJ-analysis were: • Critical users • Fingers, hands & grip • Awkward positions • Deep bends • Pain in back • Compensatory behaviors • Good with higher installation • Hardships with dishwasher on floor height • Hussle & fuss • Doesn’t pull out baskets fully • Important that it goes quickly • Layout & space • Adjustable • Quality & Robust To ensure that no smaller theme or category of importance were overlooked, each small theme and category were compiled into sub-themes and later came to be combined and translated into sub- needs. The sub-needs specified and defined the needs. 9.6 List of user needs The list of user needs emerged from the merged KJ-analysis as mentioned above (see Appendix 6: Complete list of user needs). The list of user needs was created by rephrasing the base-themes and sub-themes from the merged KJ-analysis into user needs and sub-needs. This was don