Design of an ergonomic control lever for wheel loader attachments

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actions to depending on the angles. (Osvalder et al, 2009). RULA has a subjective aspect in the ratings, so it must be regarded a semi-objective method. In this project RULA was used to analyze the work postures of the reference group from the observations in the evaluation of the functional prototype (Chapter 11.2.3). 4.2.6 User Profile The method User Profile is used to present data about user characteristics. A user profile should contain data about the user’s background, the usage and experience of the product, what influence and responsibility the user has towards the product, what kind of emotional relationship there is between the user and the product, how the user interacts with the product and what goals the user has when using the product. A product can have many types of users, not all even being in contact with the product. The users can be classified into four roles; Primary user, secondary user, Side user and Co-user. The primary user is a person who uses the product for its main purpose. A Secondary user uses or might get in contact with the product but not for its mail purpose e.g. a salesman or a repairer. The product might affect a side-user without being a primary or a secondary user e.g. someone living next to a noisy road (a car being the product). A co-user collaborated with the primary or secondary user without being in contact with the product. (Osvalder et al, 2009) In this project the user profile was used to understand the perquisites of wheel loader usage and who the machine operator is (Chapter 6.2.1). As a support to this method semistructured interviews were made with a salesman of wheel loaders, a repairman and several Swedish machine operators in the Gothenburg area. 4.3 Idea generation methods Methods used to generate ideas and finding solutions is presented here. These methods help method users to systematically find solutions, or let the participants go into idea generation phases with a certain attitude. Heuristics and guidelines are not a generally well-know methods, but the project uses them for aiming the idea generations. 4.3.1 Brainstorming This is the most recognized method to find a lot of solutions in creative sessions, where criticism is absolutely forbidden during the session (Österlin 2007). The problem to find solutions for, is phrased as a question; “how can we open product A?” (Cross, 2008, p. 48-51). For this project the brainstorming was not performed as an isolated method with external participants, and the solutions were often sketched instead of verbalized or written (Chapter 8.1 and 9.1). 4.3.2 Design heuristics and guidelines The design heuristics is regarded general aims to fulfill stated needs, and not an ideation method, although they are important for that phase. In the concept development these heuristics will be more and more defined depending on chosen ideas and concepts. This project uses the term heuristics for the defined aims to fulfill needs, and the term guidelines if a specified design feature, such as measurement is tested in the project (Chapter 7.2). 34
4.3.3 Morphological matrix Morphological matrix is a systematic method for generating new ideas. The method is based on combining part-solutions into total-solutions – giving many different totalsolutions based on how the part-solutions have been combined. First, sub-functions should be generated. For each sub-function several sub-solutions are generated. The subsolutions may advantageously be clarified with simple sketches. The sub-functions together with the respective sub-solutions are then placed into a “morphological matrix”. In the morphological matrix polygons is drawn through the sub-solutions in the matrix generating in several total-solutions. The total solutions are then sorted out based on either how well they meet requirements or just for obvious reasons. (Johannesson et al, 2004) In this project a morphological matrix was used to find new solutions in the idea generation phase after having selected one concept approach to further develop (Chapter 9.1). 4.4 Concept evaluating methods Methods that are specially used for evaluating concepts are presented below. The most common method used for this in the project is the concept screening, but other resources were available in this project. 4.4.1 Concept screening To evaluate concepts in early stages, matrices are often used. The Concept screening is a fast method, adopted by Ulrich & Eppinger (2008), where concepts are evaluated by how well they satisfy different criterion. The criterion is related to needs or requirements, and a concept gets a plus, minus or zero. It gets a zero if it fulfills the criterion as good as a reference, or plus if it fulfills it in a better. In this project concept screening was used to evaluate the concepts from the two first iterations in the concept generation (Chapter 8.3 and 9.3). The criterion used in the screening was selected based on the needs from the problem definition (Chapter 7.2). 4.4.2 Prototype rig A metal frame construction with an armrest identical to the ones in Volvo’s Wheel loaders, were available for evaluating purposes. This rig has a right side armrest fitted in the same height and with same ajdustment abilities as the armrests of current products. The future product must fit this type of armrest. This gives a mounting point and acts as a reference for instant evaluation of mock-ups and prototypes. In this projetc the prototype rig was used in the concept generatoin phase during the workshop sessions when evaluate the mock-ups (Chapter 8.1 and 9.1), when evaluating the concepts with the reference group (Chapter 8.3 and 9.3) and when developing the funcional prototype (Chapter 10.2). It was also used when developing the final concdept (Chapter 12.2) and when validating the design changes with the reference group for one last time (Chapter 12.4). 35
Page 1 and 2: Design of an ergonomic control leve
Page 3: Acknowledgements This thesis work h
Page 7 and 8: Content 1 Introduction ............
Page 9 and 10: 1 Introduction The underlying reaso
Page 11 and 12: 1.3 Question formulation The studie
Page 13 and 14: 2 Current situation To get a deeper
Page 15 and 16: Figure.2.3. Control lever unit with
Page 17 and 18: Figure 2.4.Lifting and tilting the
Page 19 and 20: 2.2.2 Technical terms related to jo
Page 21 and 22: 3 Theory The theory research gather
Page 23 and 24: Angles of movement The hand has the
Page 25 and 26: 3.1.4 Ergonomic issues related to t
Page 27 and 28: 3.2 Cognitive ergonomics It seems t
Page 29 and 30: 3.3 Standards and recommendations T
Page 31 and 32: 4 Methods This chapter consists of
Page 33: Simulation interview gives users vi
Page 37 and 38: 5 Project implementation This chapt
Page 39: Concept generation Idea generation
Page 42 and 43: Figure 6.1 the system description.
Page 44 and 45: machine operator. Because of this,
Page 46 and 47: 6.2.2 Analysis of wheel loader task
Page 48 and 49: 6.2.3 Observation study The purpose
Page 50 and 51: Working postures of L90F The operat
Page 52 and 53: Discussion observation study The fi
Page 54 and 55: Figure 6.11 Jack simulation - Good
Page 56 and 57: Result anthropometric analysis The
Page 58 and 59: 6.4 Cognitive ergonomics in wheel l
Page 60 and 61: Discussion operators’ perception
Page 62 and 63: Result of operators’ mental model
Page 64 and 65: Discussion on operators mental mode
Page 67 and 68: 7 Problem definition This is the sy
Page 69 and 70: Table 7.1 Stated needs for handle A
Page 71 and 72: 7.3 Design Heuristics Depending on
Page 73 and 74: 8 Concept generation 1 The first co
Page 76 and 77: 8.2 Concepts The ideas from the ide
Page 78 and 79: 8.3 Concept selection 8.3.1 Concept
Page 81 and 82: 9 Concept generation 2 The second c
Page 83 and 84: Sketches wrist and arm support and
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Figure 9.5 Classic joystick Figure
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10 Concept generation 3 When the ba
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Table 10.3 Elaboration of physical
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Finished functional prototype When
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easier to control the functions sim
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Housing The housing is as have been
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11 Concept evaluation This chapter
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Subjective analysis The participant
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Figure 11.4 Participant E This is a
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11.2.3 Rapid Upper Limb Assessment
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General comments from the evaluatio
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11.3 Conclusion of the evaluation T
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12 Final concept With the input fro
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Table 12.3 Elaboration of physical
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Housing To meet the technical limit
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Finished prototype The prototype re
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Figure 12.5 Angle of handle First p
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Control panel One of the reasons th
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12.5 Final remarks on the concept I
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13 Discussion Different aspects of
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method without reflections on the p
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The choice of consider the 5 th to
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14 Conclusion Discussions about the
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References Literature Adolfsson, Ni
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Figures Figure 1.1, figure 1.2, fig
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Appendix I - HTA HTA of excavating
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HTA of loading logs onto a truck: b
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VI !"#$%&'(()&*#+,-'./'*%,)(0,0&$-'
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VIII Present and Future Yes, but no
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Appendix V - Protocol !"#$#%#&&'()*
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Appendix VI - Questions 14.1.1 Over
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14.1.3 Placement In the fourth and
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14.1.4 Function In the questionnair
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Appendix VII - Result questionnaire
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XXIV
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