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This paper presents the developed 3D profilometers for surface inspection and profile measurement based on the triangulation principle. The applied compact high-resolution laser triangulation sensors with the mechatronics positioning system and computer data analysis enable the surface profile reconstruction for applications in industry as well as...
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... laser triangulation principle is founded on the measurement of the an- gle of view of a laser beam spot projected onto the object surface (Fig. 1). The light quantity distribution of the reflected beam from the object is ana- lysed and the CCD sensor detects the pixel with the laser light peak value. The position of the laser spot on the CCD sensor is related to the position of laser spot on the object surface (Fig. 2). When object is moved from position 1' to- wards 2', the ...
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... data matrix presentation enables image analysing using mathematical transformation. As shown in Fig. 10, in the image processing suitable filters can be effective. In the presented case the convolution filter was used. The results of measurement tests with highly reflective metal surfaces have shown that the output signal trace contains disturbing peaks caused by reflection of the surface microstructure (Fig. 11). In the case of the ...
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... transformation. As shown in Fig. 10, in the image processing suitable filters can be effective. In the presented case the convolution filter was used. The results of measurement tests with highly reflective metal surfaces have shown that the output signal trace contains disturbing peaks caused by reflection of the surface microstructure (Fig. 11). In the case of the applied laser head of the measured range of 10 mm, the identified and measured single peaks have a value up to 40 µm. For eliminating the peaks, the low band-pass filters and ad- vanced analysing filters can be used. The high resolution scanning of maximum area range with the linear stage step of single micrometers ...
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... As a result, the ratio of the accounting perimeter for field and laboratory conditions was 1:10 (according to Gilliot et al. (2017). To avoid possible effects of positional micro-profiling of images (Giesko et al., 2007), the camera positioning was changed in 4 positions with a shift in relation to different sides that formed the perimeter of the image area. The focusing distance for all photographic variants was 50 cm for field conditions and 25 cm for laboratory conditions. ...
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... They have shown that results are reliable and the systems are robust. There are also another studies based on the laser triangulation (with and without Scheimpflug condition) method such as measuring inner surfaces of deep holes (Ye et al., 2018) and surface quality assessment of materials (Zhang et al., 2008, Wu et al., 2020, Buschinelli et al., 2014Bracun et al., 2016), motion correction techniques for moving objects (Goel & Lohami, 2014, Blais et al., 2004Lindner et al., 2015), form, thickness, profile, liquid level and distance measuremets (Lee et al., 2013;Stöbener et al., 2003;Ghiotti et al., 2015;Zhang et al., 2014;Giesko et al., 2007;Dorsch et al., 1994;Buzinski et al., 1992, Dong et al., 2018, Tao and Liu, 2010Struckmeier et al., 2020;Donadello et al., 2018;Zhuang et al., 1994;Molleda et al., 2010;Lombardo et al., 2000;Baozhen et al., 2013;Demeyere et al., 2007), reverse engineering (Cajal et al., 2015), laser radar applications (Busk & Heiselberg, 2004) and simulation analysis (Cajal et al., 2015). ...
... Coherence scanning interferometry (CSI) provides outstanding axial resolution and dominates the world of nanometer-scale measurement [11,12]. Laser triangulation, though moving toward higher resolution, is often used for measuring larger objects [13][14][15]. ...
The article presents a new method for resolving measurement ambiguity in diffractive image microscopy (D.I.M.) for automated optical inspection (AOI) in advanced manufacturing. The D.I.M. is developed as a new microscopic profilometry for six-degrees-freedom (6DOF) surface reconstruction using a multiple-layer perceptron (MLP) to learn the underlying relationship between detected microscopic images and multiple surface geometric properties of the sample. To ensure the validity of the proposed method, there should be a one-to-one correspondence between the microscopic image and surface properties, and matching ambiguity has to be avoided through machine learning. Optical aberration exists in the microscope as the system default property is generally ineffective in generating the unique one-to-one corresponding optical transformation. By inserting additional aberration into the D.I.M., the degree of optical aberration can be quantitatively controlled to avoid mapping ambiguity between the detected diffractive image and the measured surface geometry. Experimental results showed that measurement accuracy can be achieved with a maximum height error of 1.33 μm and less than 0.123° in tilting angle. With the proposed AF-based D.I.M., it was verified that the original measurement ambiguity can be effectively avoided. Measurement errors can be further minimized by building a finer database. The proposed method is proven capable of measuring and reconstructing 3D surfaces by detecting the surface position and its orientation.
... This will result in a thicker and denser layer, causing improper bonding between layers. This porosity can be visualized either through the above-mentioned thermal imaging or even by a laser profilometer [35,39]. The laser profilometer would measure the amount of polymer that fills each layer. ...
In this review, the potential failures and flaws associated with fused deposition modeling (FDM) or fused filament fabrication (FFF) 3D printing technology are highlighted. The focus of this article is on presenting the failures and flaws that are caused by the operational standpoints and which are based on the many years of experience with current and emerging materials and equipment for the 3D printing of polymers and composites using the FDM/FFF method. FDM or FFF 3D printing, which is also known as an additive manufacturing (AM) technique, is a material processing and fabrication method where the raw material, usually in the form of filaments, is added layer-by-layer to create a three-dimensional part from a computer designed model. As expected, there are many advantages in terms of material usage, fabrication time, the complexity of the part, and the ease of use in FDM/FFF, which are extensively discussed in many articles. However, to upgrade the application of this technology from public general usage and prototyping to large-scale production use, as well as to be certain about the integrity of the parts even in a prototype, the quality and structural properties of the products become a big concern. This study provides discussions and insights into the potential factors that can cause the failure of 3D printers when producing a part and presents the type and characteristics of potential flaws that can happen in the produced parts. Common defects posed by FDM printing have been discussed, and common nondestructive detection methods to identify these flaws both in-process and after the process is completed are discussed. The discussions on the failures and flaws in machines provides useful information on troubleshooting the process if they happen, and the review on the failures and flaws in parts helps researchers and operators learn about the causes and effects of the flaws in a practical way.
... Laser profile sensors [1,2] provide very accurate depth maps at a very reasonable speed suitable for a wide range of useful tasks. Their typical final output is a 2D array containing distances from the sensor to the scanned area for each point in a 2D grid. ...
We introduce an integrated method for processing depth maps measured by a laser profile sensor. It serves for the recognition and alignment of an object given by a single example. Firstly, we look for potential object contours, mainly using the Retinex filter. Then, we select the actual object boundary via shape comparison based on Triangle Area Representation (TAR). We overcome the limitations of the TAR method by extension of its shape descriptor. That is helpful mainly for objects with symmetric shapes but other asymmetric aspects like squares with asymmetric holes. Finally, we use point-to-point pairing, provided by the extended TAR method, to calculate the 3D rigid affine transform that aligns the scanned object to the given example position. For the transform calculation, we design an algorithm that overcomes the Kabsch point-to-point algorithm’s accuracy and accommodates it for a precise contour-to-contour alignment. In this way, we have implemented a pipeline with features convenient for industrial use, namely production inspection.
... Laser profilometers are often used to investigate surfaces and factors that affect the vehicle pavement interaction at micro, macro and mega scale (e.g. tire-friction, tire-wear, hydroplaning, rolling resistance, etc) [5,6,7]. The laser scanners point cloud is adopted for the evaluation of pavement condition such as: road defects (cracks, potholes, ravelling, etc), road markings, pavement cross fall and many others. ...
... A laser profilometer (5) is mounted on the front part of the vehicle, next to the right wheel, while an odometer is located next to the front wheel rim (6). The two GPS antennas (7) are in front of the vehicle and next to (2). The PC is next to the operator, controlling the whole system (8). ...
Ensuring safety levels on roads is an imperative task for road authorities. Significant amounts of time and money are spent on performing road inspections every year. In order to ensure efficiency of road inventories, road practitioners are in need of reliable systems that are fast and are designed to comply with high standards at lower costs. To date, the 3D Mobile Mapping Systems is the most efficient, productive and accurate system used during evaluation of pavement inventories. This paper presents ViaPPS, a 3D Mobile Mapping System from ViaTech AS. ViaPPS offers accurate georeferenced data by combining the perception and navigation sensors. This paper showcases results from multiple mobile systems after the harmonization process which is held once a year to evaluate reliability and repeatability of the measurements.
... Manual measurements of gravel roads are subjective due to the location of the placed straight edges, which may produce drastically different measurements due to slight variations in placements. Therefore, alternative methods have been developed to assess gravel roads based on digital surveying technologies such as laser profilometers, laser scanners, and USAs (Giesko et al. 2007;Williams et al. 2013;Brooks et al. 2015). Among these technologies available to assess the gravel roads, ground-based lidar scanning (GBL) and UAS platforms, data can be processed to create 3D point cloud models that can be used for various road surface assessments. ...
In the state of Nebraska, over one-third of roadways are unpaved, and consequently require a significant amount of financial and operational resources to maintain their operation. Undesired behavior of surface gravel aggregates and the road surfaces can include rutting, corrugation, and ponding that may lead to reduced driving safety, speed or network efficiency, and fuel economy. This study evaluates the parameters that characterize the performance and condition of gravel roads overtime period related to various aggregate mix designs. The parameters, including width, slope, and crown profiles, are examples of performance criteria. As remote sensing technologies have advanced in the recent decade, various techniques have been introduced to collect high quality, accurate, and dense data efficiently that can be used for roadway performance assessments. Within this study, two remote sensing platforms, including an unpiloted aerial system (UAS) and ground-based lidar scanner, were used to collect point cloud data of selected roadway sites with various mix design constituents and further processed for digital assessments. Within the assessment process, statistical parameters such as standard deviation, mean value, and coefficient of variance are calculated for the extracted crown profiles. In addition, the study demonstrated that the point clouds obtained from both lidar scanners and UAS derived SfM can be used to characterize the roadway geometry accurately and extract critical information accurately.
... Despite its usability has already been validated by measuring a circular hydrodynamic jump in a liquid metal, nevertheless, it can only measure a fixed point and still needs validation before the application to liquid metal film flows under a magnetic field. Since the laser triangulation technique has been applied successfully in detecting the surface contour and vibration of objects (Bradshaw 1999;Giesko et al. 2007;Tsuji et al. 2018), it may also be possible in detecting the shape of the liquid metal film surface. Thus, it is our purpose in the present study to adopt a commercial Laser Profilometer (LP) with triangulation head to measure the surface shape and film thickness because the LP can generate a laser sheet on an object and detect any motion in a specified line with high spatial and temporal resolution (60 µm and 64 kHz (maximum value), LJ-V7300, KEYENCE). ...
... In the laser triangulation system, as plotted in Fig. 4, the measurement sensitivity is described as ds/dR = f/R sinθ, where θ is triangulation angle, f is the focal distance, R is the base distance, and ds is the offset distance of laser detected by CCD sensor (Giesko et al. 2007;Czajka et al. 2014). Usually, the commercial LP can achieve a resolution of micrometer scale which is enough for the present measurement in liquid metal film, e.g., the KEYANCE LP adopted here has a repeatability of 5 µm in the measurement of surface roughness. ...
In the fusion engineering, the liquid metal flows are considered to be an alternative solution against the solid surface in designing the plasma facing components. However, it remains unclear about the magneohydrodynamics influences on the liquid metal flows due to the lacking of experimental observations that the limited measurement method for the opaque liquid metal film should be criticized. In the present study, a laser profilometer based on the laser triangulation technique is adapted to measure the thickness of liquid GaInSn film, while a visualization method is introduced to monitor the topography of the free surface, which is formed on a horizontal substrate in the presence of a uniform transverse magnetic field. We will firstly demonstrate the applicability of a laser profilometer by measuring the thickness of GaInSn in a container with a quasi-static or dynamic free surface, to validate that the result is in good agreement with theoretical data. Using the visualization method and the laser profilometer, the evolutions of free surface waves and the time-dependent film thickness across a fixed line are measured by varying the flow rate and the magnetic field continuously. It is found that, under the influences of transverse magnetic field, the free surface waves are strongly suppressed along the spanwise direction, leaving the surface waves to propagate in the streamwise direction. More quantitatively, the measured thickness of the free surface reveals that a moderate magnetic field tends to decrease the averaged value and the root mean square value of the film thickness fluctuations while a strong magnetic field will conversely increase them. Besides, the dominant fluctuation frequencies of surface wave are observed to decrease with the increase of magnetic intensity, indicating that greater suppression is induced on the motion of small waves by the transverse magnetic field.
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... One of the most rapidly developing noncontact measurement techniques is the method involving the application of laser optical triangulation [1,2]. The sensors using this method are intended for the noncontact measurement of dislocations in the applications where high accuracy as well as the resolution and speed of measurements are required [3,4]. ...
The article presents the methodology, test stand and results of noncontact tests conducted using a laser sensor-equipped system for measuring displacement. The tests were carried out in an attempt to determine the sensitivity of the measurement system to the angular position of the sensor against the surface onto which the laser spot was projected. The scope of investigations constitutes a crucial problem dealing with the determination of tolerance of assembling a laser head in the measurement system for a laser penetrometer used for examining substance consistence. The tests were executed in the measurement range between 5 and 50 mm taking into account 5 angular positions of the laser sensor. The readings of the laser head were referred to the value of displacements adjusted with the use of a micrometric head. In the case of the tested system, the dispersion of measurement deviations was estimated as a function of the measured distance.
... W [162] zaprezentowano metodę wstępnego szacowania, która nie wymaga znajomości kształtu skanowanego elementu, natomiast w [163] opisano inną techniczną ocenę niepewności urządzenia opartego o sensor triangulacyjny, przeznaczoną dla konkretnego sensora. Procedurę szacowania niepewności pomiaru urządzenia bazującego na punktowej głowicy laserowej przedstawiono w [164]. ...
In the industry, especially automotive, the most important criterion of quality is the dimensional accordance with specification. Keeping the dimensional tolerances given by the constructor is critical from the reliability and life time point of view. For this reason, an important role in quality control play the coordinate measurements. On the market there are many coordinate measuring machines intended not only to work in the laboratory, but also on the production line. Their manufacturers have developed applications for a very wide range of applications. From small, to measure the precise details, of the size in scale of centimetres until large, having workspaces that allow for the measurements of the whole body of vans. All these machines are characterised by very large accuracies, and in addition, due to the classic, tactile nature of measurement, are relatively easy to validate. For this reason, until recently such machines were the only used in the field of geometrical quality inspection. Their main disadvantage is, however, very little speed and often limited possibility of full automation. Therefore, 100% control by means of measuring machines is impossible in large scale production. For this reason, the role of optical devices grows. Data from German industry, the most representative in terms of development trends, show that about 30% of production enterprises are going to change the current solutions to 3D non-contact optical systems and the trend is rising.
Optical measuring devices, particularly those that are based on the image analysis, allow the acquisition of more points than tactile ones. This is due to the fact that single image contains information about a large number of measuring points (> 103), depending on its resolution. In addition, the acquisition of modern cameras and communication interfaces requires just a fractions of a second. This is especially useful when mapping objects with freeform shapes, which by nature cannot be described with single values. Examples of such non-contact digitizing method are presented in Chapter 1.
Freeform surfaces are an essential element of such industries as automotive, aerospace or appliances, and the accuracy of their implementation is often a decisive influence on the efficiency and reliability. With the development of multiaxis machining techniques the number of its applications grows. A consequence of this trend is the need for quality control methods.
In this paper the focus was mainly on applications of optical 3D reconstruction methods in the industrial quality control. Very rapid expansion is observed in this field because of modern trends in production. In part I, the optical 3D reconstruction methods used in quality control will be presented. After this concise characteristics they are compared, and as a result, the method with the greatest potential for applications will be chosen. Perfect candidate appears to be the laser triangulation method which, thanks to the considerable speed and relatively simple components is used successfully for over thirty years to measure the shape of the products on the production lines. Another advantage is its resistance to external light, which is important to reduce other optical and video solutions. Thanks to the use of monochromatic light can be effectively minimized with the use of optical filters.
In the remainder of the work the source of the interference of the laser triangulation are briefly described. From there, one can see that one of the most important disturbances are internal specular reflections that arise while scanning complicated shapes containing highly reflective surfaces. They appear on the triangulation images as multiple light profiles leading to ambiguity. In this case, the 3D model reconstruction is impossible. Because this problem is crucial (it eliminates the triangulation method laser for many parts produced in the metal industry) one can find in the literature several solutions to eliminate the problem of internal reflection. They are briefly characterized in Chapter 4. One of the methods there uses the preliminary scan (pattern) of an object that satisfies the quality criteria, so that the data collected serve as the standard for filtration. Application of non-ideal detail as a golden-template and problems with data synchronization did not allow for the implementation of this concept. It was developed at a time when computer systems were not sufficiently developed to fully exploit it. The wide use of CAD/CAM systems in the modern industry, however, gives new opportunities, so that the use of this approach may be reconsidered. Each product today is manufactured according to the nominal model developed by the designer in the form of a virtual solid model. As applied to quality control, such model can therefore be used as a knowledge base for elimination of gross errors in the process of mapping shape reconstruction. Errors of this type will be in the case of laser triangulation method for example multiple profiles, which formation mechanism is described above.
However, it is not clear whether the use the knowledge of nominal object’s shape will allow for its digital reconstruction in the conditions of strong disturbances associated with surface reflectivity. Because this can be regarded as a measurement method, it is also important to proof if the changes do not derogate from its metrological capacity. Based on the above concepts and concerns a thesis has been formulated together with research tasks. Proof of the thesis requires the test implementation of the modified laser triangulation algorithms and analysis of obtained results. The use of the nominal model for 3D measurements requires extra synchronization-related treatments. Studies in this area have shown that for proper operation of the developed concepts, it is necessary to develop a stable positioning method of the object being analysed, as well as the calibration of the measuring system. They have been described in part II.
Research section (III) describes the verification of the resulting modification of laser triangulation method. In accordance with the thesis its proof requires both the investigation if a new segmentation algorithm eliminates internal reflections, and improves the accuracy of the scan. The first part was carried out using the two examples that manifest very well internal, specular reflections. The first is the v-block, and the other is a shiny freeform surface. Investigations have confirmed the effectiveness of the algorithm. In the second part it was necessary to designate the measuring uncertainty of triangulation setup. The phenomenon of multiple reflection does not, however, manifests in the standard procedure of uncertainty estimation, that requires multiple measurements of gauge blocks. It would therefore be necessary to use more specialized patterns. These, however, significantly impede research carried out under repeatability conditions. A simplified estimation method of measurement’s uncertainty, has been proposed based on the assumption that the segmentation accuracy is one of the components of the uncertainty budget. The convergence of the results of this estimation method and the classic method, argues that the standard assumptions about the immediate impact of the segmentation accuracy on the uncertainty of the measurements. The results suggest that segmentation algorithm improved the ability to detect light profile and, therefore, also contributed to improving the measurement uncertainty.
The last part of the work (IV) summarizes the developed solution and the outcome of the tests.
