Research on the High Precision Laser Line Scanning Measuring System

2007 ◽  
Vol 339 ◽  
pp. 131-135 ◽  
Author(s):  
Jian Jun Ding ◽  
Zhuang De Jiang ◽  
Bing Li ◽  
Jun Jie Guo
Keyword(s):  
High Precision ◽  
Laser Scanning ◽  
Laser Line ◽  
Measuring System ◽  
Surface Measurement ◽  
Iteration Algorithm ◽  
Reconstruction Method ◽  
Loop Feedback ◽  
Axis Position ◽  
Line Scanning

Rapid reverse technology is one of the key technologies with which the enterprises develop new product and occupy the market rapidly. How to realize the reverse measurement and CAD geometry reconstruction rapidly and accurately is always the most important focus for the researchers. Based on the laser scanning technology, the realization principle of the laser line scanning measuring system is presented and the approaches to improve the precision are also analysed in the paper. The self-adaptation adjustment of the probe position can move the light knife image to the optimal imaging area of the CCD according to the calibration result, which will ensure the measurement precision of the CCD image. With the inner velocity loop and outer position loop feedback control, the simple axis position precision of the mechanical system can be controlled within 5um. In order to pick up the points of the light knife centre rationally and exactly, the reconstruction-disperse iteration algorithm is put forward. After processed by different iteration times, the optimal points can be obtained. The reconstruction method of curve and surface based on NURBS is also given. The paper presents the application and realization of the system at last, which realizes the curve and surface measurement with high precision.

The influence of surface topology on the quality of the point cloud data acquired with laser line scanning probe

Sensor Review ◽  
2014 ◽  
Vol 34 (3) ◽  
pp. 255-265 ◽  
Author(s):  
Syed Hammad Mian ◽  
Mohammed Abdul Mannan ◽  
Abdulrahman M. Al-Ahmari
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Specular Reflection ◽  
Surface Characteristics ◽  
Laser Line ◽  
Scanning Probe ◽  
Surface Topology ◽  
Polished Surface ◽  
Content Type ◽  
Line Scanning

Purpose – The purpose of this paper is to investigate the influence of surface topology on the performance of laser line scanning probe and to suggest methodology for 3D digitization of specular surfaces. Design/methodology/approach – Two different molds, one having milled surface and the other with polished surface, were used to identify effect of surface characteristics on the performance of laser line scanning probe mounted on bridge-type coordinate measuring machine. The point cloud data acquisition of two surfaces was carried out using different combinations of laser scanning parameters. The point cloud sets thus obtained were analyzed in terms of completeness, noise and accuracy. The polished mold which exhibited specular reflection was digitized at different scanning angles of laser line scanning probe using the best combination of scanning parameters. Findings – Results confirmed that surface characteristics play important role to determine quality of the reverse engineering (RE) process. The results in terms of completeness, accuracy and noise for point cloud sets have successfully been obtained for milled and polished surfaces. Three-dimensional (3D) comparison analysis suggested larger deviation in cases of polished surface as compared to milled surface. The point cloud set acquired with proposed approach was better in terms of both completeness and noise reduction. Originality/value – There has been an increased demand for measurement of metallic, polished and shiny surfaces in automotive, aerospace and medical industries. These surfaces are very difficult to scan because they exhibit specular reflection instead of diffuse reflection. Laser line scanning probe which is a non-contact method is in great demand for RE. This is due to the fact that it possesses very high data acquisition speed. However, laser scanning is hugely affected by surface characteristics which in turn govern specular reflection.In this paper, it has been shown that a surface that exhibits various degrees of specular reflection can be digitized efficiently if appropriate combination of scanning parameters and positions of laser line scanning probe are used. Also, this paper has attempted to offer a procedure to overcome incompleteness and noise in 3D data as obtained by the laser line scanning probe.

scholarly journals OPTICAL TRIANGULATION ON INSTATIONARY WATER SURFACES

2016 ◽  
Vol XLI-B5 ◽  
pp. 85-91
Author(s):  
C. Mulsow ◽  
H.-G. Maas ◽  
B. Hentschel
Keyword(s):  
Water Level ◽  
Laser Light ◽  
Light Sheet ◽  
Water Levels ◽  
Laser Line ◽  
Frame Rate ◽  
Measuring System ◽  
Optical Triangulation ◽  
Dynamic Experiments ◽  
Water Surfaces

The measurement of water surfaces is a key task in the field of experimental hydromechanics. Established techniques are usually gauge-based and often come with a large instrumental effort and a limited spatial resolution. The paper shows a photogrammetric alternative based on the well-known laser light sheet projection technique. While the original approach is limited to surfaces with diffuse reflection properties, the developed technique is capable of measuring dynamically on reflecting instationary surfaces. Contrary to the traditional way, the laser line is not observed on the object. Instead, using the properties of water, the laser light is reflected on to a set of staggered vertical planes. The resulting laser line is observed by a camera and measured by subpixel operators. A calibration based on known still water levels provides the parameters for the translation of image space measurements into water level and gradient determination in dynamic experiments. As a side-effect of the principle of measuring the reflected laser line rather than the projected one, the accuracy can be improved by almost a factor two. In experiments a standard deviation of 0.03 mm for water level changes could be achieved. The measuring rate corresponds to the frame rate of the camera. A complete measuring system is currently under development for the Federal Waterways Engineering and Research Institute (BAW). <br><br> This article shows the basic principle, potential and limitations of the method. Furthermore, several system variants optimised for different requirements are presented. Besides the geometrical models of different levels of complexity, system calibration procedures are described too. The applicability of the techniques and their accuracy potential are shown in several practical tests.

scholarly journals A Model Study of Building Seismic Damage Information Extraction and Analysis on Ground-Based LiDAR Data

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Fan Yang ◽  
Xintao Wen ◽  
Xiaoshan Wang ◽  
Xiaoli Li ◽  
Zhiqiang Li
Keyword(s):  
High Precision ◽  
Laser Scanning ◽  
Full Range ◽  
Scientific Basis ◽  
Building Damage ◽  
Vector Model ◽  
Lidar Data ◽  
Emergency Relief ◽  
Cloud Data ◽  
Ground Based Lidar

Earthquake disasters can have a serious impact on people’s lives and property, with damage to buildings being one of the main causes of death and injury. A rapid assessment of the extent of building damage is essential for emergency response management, rescue operations, and reconstruction. Terrestrial laser scanning technology can obtain high precision light detection and ranging (LiDAR) point cloud data of the target. The technology is widely used in various fields; however, the quantitative analysis of building seismic information is the focus and difficulty of ground-based LiDAR data analysis processing. This paper takes full advantage of the high-precision characteristics of ground-based LiDAR data. A triangular network vector model (TIN-shaped model) was created in conjunction with the alpha shapes algorithm, solving the problem of small, nonvisually identifiable postearthquake building damage feature extraction bias. The model measures the length, width, and depth of building cracks, extracts the amount of wall tilt deformation, and labels the deformation zone. The creation of this model can provide scientific basis and technical support for postearthquake emergency relief, assessment of damage to buildings, extraction of deformation characteristics of other structures (bridges, tunnels, dams, etc.), and seismic reinforcement of buildings. The research data in this paper were collected by the author’s research team in the first time after the 2013 Lushan earthquake and is one of the few sets of foundation of LiDAR data covering the full range of postearthquake building types in the region, with the data information mainly including different damage levels of different structural types of buildings. The modeling analysis of this data provides a scientific basis for establishing the earthquake damage matrix of buildings in the region.

scholarly journals Dynamic Behaviour of a Conveyor Belt Considering Non-Uniform Bulk Material Distribution for Speed Control

2020 ◽  
Vol 10 (13) ◽  
pp. 4436
Author(s):  
Fei Zeng ◽  
Cheng Yan ◽  
Qing Wu ◽  
Tao Wang
Keyword(s):  
Dynamic Model ◽  
High Precision ◽  
Material Flow ◽  
Laser Scanning ◽  
Bulk Material ◽  
Speed Control ◽  
Conveyor Belt ◽  
Distribution Model ◽  
Material Distribution ◽  
Belt Conveyor

For the conveyor belt, variable material flow influences the energy efficiency of the speed control technology significantly. The fluctuation of material flow on the conveyor belt will lead to the detrimental vibrations on both the belt and the conveyor while the conveyor works at certain speeds. In order to improve the model inaccuracy caused by the uniform bulk material flow assumption in the current conveyor belt model, the paper establishes a high-precision dynamic model that can consider speed control of a conveyor belt under non-uniform bulk material transportation. In this dynamic model, a non-uniform bulk material distribution model is firstly proposed based on laser scanning technology. Then, a high-precision longitudinal dynamic model is proposed to investigate the dynamic behavior of a belt conveyor. Considering the micro-units of actual load on a conveyor belt, it can well describe the transient state of the conveyor belt. These models can be used to determine the optimal speed for safety and energy conservation in operation. Experimental results are used to validate the proposed dynamic model for analyzing belt mechanical behavior under non-uniform bulk material distribution on the belt. The results show that the proposed models can be used for optimizing the operating procedures of belt conveyor systems.

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