Design of an ergonomic control lever for wheel loader attachments

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20 Figure 2.9 Image board Single levers The three upper images are thumb-controlled joystick. The two to the left is located in a Ålö front loader and the one to the right is located in a Ponsse forestry harvester. The two joysticks to the lower left are both located in wheel loaders. They are defined as regular joysticks; the upper is made by LiuGong, and the lower by CAT. The two images to the lower right are defined as mini-joysticks. The upper image is located in a John Deere harvester and the lower image is from a Valtra tractor.
3 Theory The theory research gathers facts for a deeper understanding of the ergonomic limitations of human physics and also describes what aspects that are important for cognitive ergonomics. Regarding the physical ergonomics, the anatomy of the hand and hand function is presented together with factors that impact the workload. A summary relates the facts to the work in wheel loaders and encloses what ergonomic issues that exist today. The cognitive ergonomics chapter presents theories of perception processing and why mental models should be studied. The cognitive ergonomics chapter mostly explains terms and concepts and why they are used in this project. A chapter of standards and recommendations from literature studies, related to wheel loaders and control lever design, summarize the theory chapter. 3.1 Physical ergonomics The control lever unit mainly involves the use of the hand and requires dexterity and precision from it. Therefore it is important to consider the variables in hand work to understand what influences effectiveness, comfort and efficiency of hand related work (Haslegrave & Pheasant, 2006). The overall work posture – especially the position of the arm will have effects on whether the operator will experience discomforts or not. The overall work posture is related to the chair and the armrest, which is outside of this project scope, and will therefore not be included in any deeper analyze. Forestry machines, such as forestry harvesters facilitates a work situation that is not identical, but in some aspects similar to wheel loaders. Some research has been done on this topic in an ergonomic aspect and some of this research relevant for the project is used in this chapter. In several situations there is useful to use planes to describe postures or other movements. Well-recognized plans that relate the human body to the surrounding world are the following (Leonard, 1995): 1: the sagittal plane that divides the body in the left and right halves 2: the coronal (or frontal plane) divides the body into the front and back halves 3: the transverse plane is horizontal that divides the body into the upper and lower halves. Figure 3.1 Muscles (Bartleby 1918) 21
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: 2.2.2 Technical terms related to jo
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 and 34: Simulation interview gives users vi
Page 35 and 36: 4.3.3 Morphological matrix Morpholo
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
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7.3 Design Heuristics Depending on
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8 Concept generation 1 The first co
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8.2 Concepts The ideas from the ide
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8.3 Concept selection 8.3.1 Concept
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9 Concept generation 2 The second c
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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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