Master Thesis - Fachbereich Informatik

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3. Hardware Configuration This chapter introduces the physical design of the visual inspection prototype. This includes the conveyor, the camera setup, the choice of illumination as well as the blow out mechanism. Figure 3.1 gives an overview on the hardware setup of the prototype. 3.1. Conveyor For the prototype, a 200cm long and 10cm wide conveyor is used to simulate a production line. It can be manually fit with several tube segments where the exact number depends on the target length and the distance between two consecutive segments. The measuring is performed at a certain area of the conveyor denoted as measuring area in the following. The field of view of the camera is adjusted to this area, as well as the illumination as will be introduced in Section 3.2 and 3.3 respectively. The dimension of the measuring area depends on the size of the tubes to be measured. Therefore, with respect to the range of tube sizes, the measuring area is designed to cover the maximum tube size of 100mm in length and about 12mm in diameter. It must be even larger to be able to capture several images of each tube while passing the visual field of the camera. Since in production the tubes are cut to lengths from a continuous tube using a rotating knife (flying knife), there would not be a notable spacing between two consecutive tube segments if transfered to the measuring area with the same speed as entering the knife. Thus, it can be difficult to determine where one tube starts and ends in the continuous line by looking both for humans and artificial vision sensors. To overcome this problem, after cutting, the tube segments have to fall onto another conveyor with a faster velocity to separate them. The faster the second conveyor is compared to the first one, the larger the gap. Since processing time is expensive, the goal is to simplify the measuring conditions as much as possible using an elaborated hardware setup. One easy but effective simplification is to mount two guide bars to the conveyor that guarantee almost horizontal oriented tube segments. The guide bars are arranged like a narrow ‘V’ (see Figure 3.1(b)). The tubes enter the guide bars at the wider end and are adjusted into horizontal position while moving. At the measuring area the guide bars are almost parallel and just slightly wider than the diameter of the tubes. The distance of the guide bars can be easily changed using adjusting screws if the tube type changes. The color and structure of the conveyor belt is crucial to maximize the contrast between objects and background for the inspection task. Therefore, a white-colored belt is used. The advantage of this choice with respect to the range of tube types to be inspected in combination with the illumination setup will be discussed in more detail in Section 3.3. 31
32 CHAPTER 3. HARDWARE CONFIGURATION (a) (b) Figure 3.1: Hardware setup of the prototype in the laboratory environment. (a) Total view. (b) View on the measuring area.
Page 1 and 2: Fachbereich Informatik Department o
Page 4: Acknowledgments First of all, I wou
Page 8 and 9: Contents Acknowledgments iii Abstra
Page 10 and 11: Contents ix 5.3.7. TubeLength .....
Page 12 and 13: List of Tables 1.1. Rangeoftubetype
Page 14 and 15: List of Figures 2.1. AccuracyandPre
Page 16 and 17: 1. Introduction Heat shrinkable tub
Page 18 and 19: 1.2. PROBLEM STATEMENT 3 hazards, r
Page 20 and 21: 1.4. RELATED WORK 5 Length [mm] Tol
Page 22 and 23: 1.5. THESIS OUTLINE 7 The vision pa
Page 24 and 25: 2. Technical Background 2.1. Visual
Page 26 and 27: 2.1. VISUAL MEASUREMENTS 11 (a) Fig
Page 28 and 29: 2.1. VISUAL MEASUREMENTS 13 Figure
Page 30 and 31: 2.1. VISUAL MEASUREMENTS 15 � xd
Page 32 and 33: 2.2. ILLUMINATION 17 tubes alternat
Page 34 and 35: 2.2. ILLUMINATION 19 effect of comp
Page 36 and 37: 2.3. EDGE DETECTION 21 i 2 i 1 0 (a
Page 38 and 39: 2.3. EDGE DETECTION 23 N × 1 kerne
Page 40 and 41: 2.3. EDGE DETECTION 25 These operat
Page 42 and 43: 2.3. EDGE DETECTION 27 (a) 0 ◦ (b
Page 44 and 45: 2.4. TEMPLATE MATCHING 29 accuracy
Page 48 and 49: 3.2. CAMERA SETUP 33 3.2. Camera se
Page 50 and 51: 3.2. CAMERA SETUP 35 eachcolorchann
Page 52 and 53: 3.2. CAMERA SETUP 37 Figure 3.4: Co
Page 54 and 55: 3.2. CAMERA SETUP 39 adjusting scre
Page 56 and 57: 3.2. CAMERA SETUP 41 further distan
Page 58 and 59: 3.3. ILLUMINATION 43 f V 12mm 129mm
Page 60 and 61: 3.3. ILLUMINATION 45 (a) (b) (c) Fi
Page 62 and 63: 3.3. ILLUMINATION 47 (a) (b) Figure
Page 64 and 65: 3.4. BLOW OUT MECHANISM 49 A light
Page 66 and 67: 4. Length Measurement Approach Whil
Page 68 and 69: 4.2. MODEL KNOWLEDGE AND ASSUMPTION
Page 74 and 75: 4.3. CAMERA CALIBRATION 59 4.2.7. B
Page 76 and 77: 4.3. CAMERA CALIBRATION 61 Figure 4
Page 78 and 79: 4.3. CAMERA CALIBRATION 63 is compu
Page 80 and 81: 4.4. TUBE LOCALIZATION 65 (a) (b) F
Page 82 and 83: 4.4. TUBE LOCALIZATION 67 � 1 Psm
Page 84 and 85: 4.4. TUBE LOCALIZATION 69 Global Th
Page 86 and 87: 4.4. TUBE LOCALIZATION 71 but also
Page 88 and 89: 4.4. TUBE LOCALIZATION 73 Global Re
Page 90 and 91: 4.5. MEASURING POINT DETECTION 75 f
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4.5. MEASURING POINT DETECTION 81 0
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4.5. MEASURING POINT DETECTION 83 o
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4.5. MEASURING POINT DETECTION 85 (
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4.5. MEASURING POINT DETECTION 87 w
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4.6. MEASURING 89 side of the tube,
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4.6. MEASURING 91 fcor(x) =−(c1x
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4.7. TEACH-IN 93 inthemeasuringplan
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4.7. TEACH-IN 95 The pair of a pixe
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5. Results and Evaluation 5.1. Expe
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5.1. EXPERIMENTAL DESIGN 99 between
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5.1. EXPERIMENTAL DESIGN 101 where
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5.1. EXPERIMENTAL DESIGN 103 Ground
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5.2. TEST SCENARIOS 105 enough, the
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5.3. EXPERIMENTAL RESULTS 107 The t
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5.3. EXPERIMENTAL RESULTS 109 Detec
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5.3. EXPERIMENTAL RESULTS 111 Lengt
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5.3. EXPERIMENTAL RESULTS 113 GTD [
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5.3. EXPERIMENTAL RESULTS 115 gray
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5.3. EXPERIMENTAL RESULTS 119 (a) (
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5.3. EXPERIMENTAL RESULTS 121 (a) (
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5.3. EXPERIMENTAL RESULTS 125 Total
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5.3. EXPERIMENTAL RESULTS 127 Color
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5.3. EXPERIMENTAL RESULTS 129 Task
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5.4. DISCUSSION AND FUTURE WORK 131
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6. Conclusion In this thesis a func
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Appendix 135
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138 APPENDIX A. PROFILE ANALYSIS IM
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140 APPENDIX A. PROFILE ANALYSIS IM
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142 APPENDIX B. HARDWARE COMPONENTS
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144 APPENDIX B. HARDWARE COMPONENTS
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146 Bibliography [18] C. Demant, B.
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148 Bibliography [51] K.K. Pingle.
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Master Thesis - Fachbereich Informatik

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