development of a vision system for ship hull ... - ePrints@USM

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Although the proposed system is mainly depending on the laser, there are somedisadvantages of using laser device has to be taken into consideration. For instance,light is absorbed by water (which may also be useful) and by the debris producedduring processing. Furthermore, light may be scattered by the water surface,suspensions and bubbles, and possible power loss due to water cooling (Kruusing,2002).In brief, this section had discussed the factors that contribute to the accuracy inlaser range measurement technique. As a preliminary study, the theoretical explanationin this section will be tested.2.5 SummaryIn this chapter, the ship hull inspection technology, underwater laser andunderwater guidance and control have been reviewed. Since underwater laserapplication has undergone several positive developments recently, small issueregarding its weakness as mentioned in previous section can be neglected. Howeverthe main challenge is to perform high speed loop control respond and precision inmeasurement as well. Selection of proper hardware devices and programmingtechnique may overcome this problem. In order to develop the system, the need of theparticular goals have been taken into consideration. Among the key design issuesaddressed are Cartesian platform as an ROV, pan-tilt camera, laser device positions,feature extraction techniques, real time programming language, calibration methods,controller, ship hull prototype and underwater environment. These subjects will bediscussed in details throughout the thesis.22
CHAPTER THREETHEORY3.0 IntroductionA theoretical explanation of the research is discussed in details in this chapter.A Cartesian platform is used to emulate the ROV’s movement. It is similar to setupwhich had been done by Lots et al. (2001) to emulate the six DOF of the ROV.Assuming the underwater environment characteristics are known, this research willfocuses on how to develop the vision-based tracking system itself. The permeationcharacteristics of visible light in water, turbidity effects, laser beam detection forunderwater applications and underwater laser triangulations, are also discussed in thischapter.Scaled-down ship hull section is developed and used as the target object,painted with the actual anticorrosion paint (dark maroon). Grids of 10cm x 10cm aremarked on the ship hull model surface so that it can provide some mean for the visualobservation, measurement and analysis. Finally, this research adopts a set of metricsand performance criteria from feedback control theory to characterize the dynamicperformance of the tracking system.24
Page 2 and 3: DEVELOPMENT OF A VISION SYSTEM FOR
Page 5 and 6: CHAPTER THREE : THEORY3.0 Introduct
Page 7 and 8: LIST OF PUBLICATIONS & SEMINARS 119
Page 9 and 10: LIST OF FIGURESPageFigure 1.1 Examp
Page 11 and 12: Figure 5.6 Captured images: Manuall
Page 13 and 14: dL1L2L3dLAdLBdLCLaLbLaCxLa,CyLaCxLb
Page 15 and 16: PEMBANGUNAN SEBUAH SISTEM PENGLIHAT
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Page 19 and 20: photographed. The inspector may als
Page 21 and 22: • To study the usage of a laser f
Page 23 and 24: 2.0 IntroductionCHAPTER TWOLITERATU
Page 25 and 26: 2.1.1 The need of an ROV for inspec
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Page 29 and 30: In short, in order to measure a sma
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Page 35 and 36: 2.3.2 Single point projectionYu et
Page 37: 2.4.2 Hardware manipulationIn terms

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