- 标题
- 摘要
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- 实验方案
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High-Precision 3D Object Capturing with Static and Kinematic Terrestrial Laser Scanning in Industrial Applicationsa??Approaches of Quality Assessment
摘要： Terrestrial laser scanning is used in many disciplines of engineering. Examples include mobile mapping, architecture surveying, archaeology, as well as monitoring and surveillance measurements. For most of the mentioned applications, 3D object capturing in an accuracy range of several millimeters up to a few centimeters is sufficient. However, in engineering geodesy, particularly in industrial surveying or monitoring measurements, accuracies in a range of a few millimeters are required. Additional increased quality requirements apply to these applications. This paper focuses on the quality investigation of data captured with static and kinematic terrestrial laser scanning. For this purpose, suitable sensors, which are typically used in the approach of a multi-sensor-system, as well as the corresponding data capturing/acquisition strategies, are presented. The aim of such systems is a geometry- and surface-based analysis in an industrial environment with an accuracy of +/? 1–2 mm or better.
关键词： synchronization,quality analysis,laser tracker,high-precision terrestrial laser scanning,multi-sensor-systems,calibration,industrial surveying,kinematic laser scanning,forward modeling,backward modeling
更新于2025-09-23 15:19:57
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A Novel Approach to Separate Geometric Error of the Rotary Axis of Multi-axis Machine Tool Using Laser Tracker
摘要： It is highly desirable to enhance machining accuracy for multi-axis machine tool, in which the geometric accuracy of rotary axis is a main contributing factor. Thus, how to achieve the fast and accurate identification of each geometric error of rotary axis, as well as its correction and compensation has become a key issue. This paper presents a novel method of geometric error separation of the rotary axis by means of laser tracker. For this method, the direction variation of the vectors composed by some adjacent measuring points during the rotation of turntable is measured, and rotary axis’s six geometric errors including three linear displacement and three angular displacement errors can be accurately identified on the basis of the mapping relationship between the vector’s direction variation and each geometric error. Meanwhile, the multi-station and time-sharing measurement is adopted based on GPS principle, aiming to overcome the effect of angle measurement error using laser tracker. Eventually, the geometric error separation mathematical model on rotary axis with this novel method is established, and the corresponding measurement algorithms containing the base station calibration and the measuring point determination based on the hybrid genetic algorithm, as well as each geometric error separation algorithm are deduced respectively. Furthermore, the numerical simulations are conducted to examine the validity of the derived algorithms. Results of the comparative experiment demonstrate that high-efficiency and high-precision measurement for the geometric error of the rotary axis can be accomplished by the proposed approach.
关键词： Error identification,Rotary axis,Laser tracker,Measurement algorithm
更新于2025-09-19 17:13:59
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Methods to calibrate a three-sphere scale bar for laser scanner performance evaluation per the ASTM E3125-17
摘要： A scale bar with sphere targets is one way of realizing the symmetric and asymmetric length tests to evaluate Terrestrial Laser Scanner (TLS) performance per the ASTM E3125-17 standard. The length of the scale bar is required to be known with an expanded (k = 2) uncertainty that must be at least four times smaller than the manufacturer’s maximum permissible error (MPE) specification of the instrument being tested. In this paper, we propose two methods to calibrate the scale bar length using a laser tracker. The first method, which we refer to as the four-orientation and two-face (FOTF) method, is proposed for calibrating the scale bar when it is in a horizontal orientation. The other method, which we refer to as the comparison method, is proposed for calibrating the length of the scale bar in any orientation. We describe the methods, present underlying theories, discuss validation experiments, and summarize results. The two calibration methods are beneficial for the realization of the ASTM E3125-17 standard for TLS performance evaluation.
关键词： Three sphere scale bar,ASTM E3125-17,Terrestrial laser scanner,Laser tracker,Length calibration
更新于2025-09-16 10:30:52
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Flexible method for accurate calibration of large-scale vision metrology system based on virtual 3-D targets and laser tracker
摘要： For the purpose of obtaining high-precision in stereo vision calibration, a large-size precise calibration target, which can cover more than half of the field of view is vital. However, large-scale calibration targets are very difficult to fabricate. Based on the idea of error tracing, a high-precision calibration method for vision system with large field of view by constructing a virtual 3-D calibration target with a laser tracker was proposed in this article. A virtual 3-D calibration target that covers the whole measurement space can be established flexibly and the measurement precision of the vision system can be traceable to the laser tracker. First, virtual 3-D targets by calculating rigid body transformation with unit quaternion method were constructed. Then, the high-order distortion camera model was taken into consideration. Besides, the calibration parameters were solved with Levenberg–Marquardt optimization algorithm. In the experiment, a binocular stereo vision system with the field of view of 4 (cid:2) 3 (cid:2) 2 m3 was built for verifying the validity and precision of the proposed calibration method. It is measured that the accuracy with the proposed method can be greatly improved comparing with traditional plane calibration method. The method can be widely used in industrial applications, such as in the field of calibrating large-scale vision-based coordinate metrology, and six-degrees of freedom pose tracking system for dimensional measurement of workpiece, as well as robotics geometrical accuracy detection and compensation.
关键词： error tracing,virtual 3-D target,Large-scale vision metrology system,laser tracker,calibration
更新于2025-09-16 10:30:52
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Determination of Laser Tracker Angle Encoder Errors
摘要： Errors in the angle encoders of a laser tracker may potentially produce large errors in long range coordinate measurements. To determine the azimuth angle encoder errors and verify their values stored in the tracker’s internal error map, several methodologies were evaluated, differing in complexity, measurement time and the need for specialised measuring equipment. These methodologies are: an artefact-based technique developed by NIST; a multi-target network technique developed by NPL; and the classical precision angular indexing table technique. It is shown that the three methodologies agree within their respective measurement uncertainties and that the NPL technique has the advantages of a short measurement time and no reliance on specialised measurement equipment or artefacts.
关键词： Precision Angular Indexing Table,NIST technique,NPL network technique,Angle Encoder Errors,Laser Tracker
更新于2025-09-16 10:30:52
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Thermal Deformation Compensation of Laser Tracker Relocating in Aircraft Assembly
摘要： During aircraft assembly, measurements from either a single or multiple laser tracker with different positions are transformed to an assembly coordinate system by measuring the enhanced reference system (ERS) points via a rigid-body registration method. The location deviations of the ERS points resulting from thermal deformations have become the major error source in registration. To improve the accuracy of measurement, a thermal deformation compensation method, based on precise thermal deformation theory, is proposed in this study. Thermal deformation coefficients of ERS points in X-, Y-, and Z-axes are calculated separately, and an iterative algorithm is developed to correct the actual locations of the ERS points and estimate the optimal coordinate transformation parameters. A case study indicated that, with our proposed novel thermal deformation compensation method, the average registration error is decreased by 9.2–38.7%, and the maximum registration error is deceased by 12.3–38.6%.
关键词： Laser tracker relocating,Thermal deformation coefficient,Enhanced reference system point,Location deviation,Large-volume metrology
更新于2025-09-16 10:30:52
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The generation and validation of a CUF-based FEA model with laser-based experiments
摘要： Architectural structures today are increasingly complex and structural health monitoring plays an important role in guaranteeing their safety. How to improve the reliability of deformation analysis is, thus, one of the key problems. This article combines laser-based measurement technology and the Carrera unified formulation (CUF) method to investigate the deformation of engineering structures. Within this article, we simulate architectural structures using the CUF geometric model, which is consistent with the results of the laser tracker experiment. We aimed at constructing an intelligent and efficient CUF model which can be applied extensively in the monitoring of various constructs, such as tunnels and bridges. The innovation of this article is that high-accuracy laser tracker technology is integrated with an effective CUF model to investigate the load-displacement relationship considering lateral displacement.
关键词： multi-sensor,laser tracker,SHM,FEA,terrestrial laser scanning
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE International Conference on Mechatronics and Automation (ICMA) - Tianjin, China (2019.8.4-2019.8.7)] 2019 IEEE International Conference on Mechatronics and Automation (ICMA) - Kinematics Calibration of Spraying Robot based on Laser Tracker
摘要： A method for industrial spraying robot calibration by using laser tracker is presented in this paper. Firstly, the structure of spraying robot is analysed and the coordinate systems of each joint are configured based on D-H method; Secondly, the kinematics model of spraying robot is established, and the error model of the spraying robot is established based on the differential transformation. Thus the functional equation between the position error of the end-effector and the D-H parameters is obtained; Thirdly, laser tracker is used to measure the actual position of the end-effector, and the error of D-H parameters of each joint are iteratively solved based on the kinematics error model; Finally, the error value is compensated to the robot motion control model for verification. The results of the experiment show that the absolute precision of the robot is improved greatly after calibration.
关键词： Kinematics Calibration,Laser Tracker,Spraying robot,Kinematics modeling
更新于2025-09-12 10:27:22
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Optimized free-form surface modeling of point clouds from laser-based measurement
摘要： Freeform parameterizations to reproduce structure deformation are increasingly important topics in laser-scanner-based deformation analyses. High-accuracy assurance of free-form surface approximation is extremely critical for reliable deformation analysis. One main challenge in this field is the model selection. Improper model complexity could result in under-fitting the real object shape or overfitting data noises, and thus a failure of deformation analysis. A multi-sensor system could integrate advantages of different sensors and improve the quality of mission completed. This paper combines terrestrial laser scanning (TLS) and laser tracker (LT) technologies, to enhance high-accuracy surface modeling in deformation analysis. A surface-based B-spline approximation and a multi-sensor system are investigated, the latter of which focuses mainly on the combination of TLS and LT technologies. The innovation of this paper is that the surface-based B-spline approximation is validated and optimized with LT corner cube reflectors. Hypothesis testing is adopted to select the best parameter setting by judging most consistency of TLS and LT in various epochs. In the B-spline surface modeling, both instrumental and numerical uncertainties are considered. We use the instrumental uncertainty model based on intensity value, as well as numerical uncertainty based on adjustment theories. A sampling strategy is proposed to avoid data gaps and obtain even distributed data points.
关键词： multi-sensor,laser tracker,Surface modeling,B-spline approximation,terrestrial laser scanning
更新于2025-09-11 14:15:04
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3D Measurement Simulation and Relative Pointing Error Verification of the Telescope Mount Assembly Subsystem for the Large Synoptic Survey Telescope
摘要： An engineering validation of a large optical telescope consists of executing major performing tests at the subsystem level to verify the overall engineering performance of the observatory. Thus, the relative pointing error verification of the telescope mount assembly subsystem is of special interest to guarantee the absolute pointing performance of the large synoptic survey telescope. This paper presents a new verification method for the relative pointing error assessment of the telescope mount assembly, based on laser tracker technology and several fiducial points fixed to the floor. Monte-Carlo-based simulation results show that the presented methodology is fit for purpose, even if floor movement occurs due to temperature variation during the measurement acquisition process. A further research about laser tracker technology integration into the telescope structure may suggest that such laser tracker technology could be permanently installed in the telescope in order to provide an active alignment system that aims to detect and correct possible misalignment between mirrors or to provide the required mirror positioning verification accuracy after maintenance activities. The obtained results show that two on-board laser tracker systems combined with eight measurement targets could result in measurement uncertainties that are better than 1 arcsec, which would provide a reliable built-in metrology tool for large telescopes.
关键词： RPE,mirror positioning,laser tracker,telescope mount assembly (TMA),large synoptic survey telescope (LSST),active alignment system,simulation
更新于2025-09-09 09:28:46