Techniques for measuring and compensating for servo mismatch in machine tools using a laser tracker

Lee, Hoon Hee; Son, J. H.; Yang, Seung-Han

doi:10.1007/s00170-017-0382-2

Cited by 16 publications

(3 citation statements)

References 9 publications

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“…Since the measurement errors of the laser tracker along the horizontal and vertical direction are almost the same (i.e. assuming m α = m β ), the mean square error of the slope taping between two points is m r , then the error estimation equation for point P is 13…”

Section: The Measurement Accuracy Analysis Of the Laser Trackermentioning

confidence: 99%

Method of improving large-scale measurement accuracy of laser tracker based on photogrammetry

Zhang

Jing

Chen

et al. 2019

Measurement and Control

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Background: When performing the spatial large-scale measurements, the measurement accuracy of laser tracker would decreased with the increase of the measurement distances due to the refraction difference of most optical digital measurement devices. Therefore, this paper proposed a method based on photogrammetry system to improve the large-scale measurement accuracy of the laser tracker. Purpose: The purpose of this method is to improve the large-scale measurement accuracy of the laser tracker by considering the advantages of photogrammetry system such as high measurement accuracy and good portability. Methods: The measurement data from the photogrammetry system would be used as a reference to do correction on measurement results from laser tracker. The coordinate correction method based on Rodrigues’ rotation formula has been discussed. The measurement accuracy of the long-distance point of laser tracker can be significantly improved through the coordinate correction method. Conclusion: Based on the advantages of using photogrammetry system, the proposed method can achieve higher accuracy when measuring the common points at a closer distance than the laser tracker can do when measuring objects far away from instrument. The feasibility of the proposed method has been demonstrated by experiment.

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Section: The Measurement Accuracy Analysis Of the Laser Trackermentioning

confidence: 99%

Method of improving large-scale measurement accuracy of laser tracker based on photogrammetry

Zhang

Jing

Chen

et al. 2019

Measurement and Control

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“…Thus, it can be seen that the topics covered in the two conferences are of great importance to CNC machine tool end users [8]. To summarize the current standards and state of the art, the equipment used to evaluate the dynamic performance of machine tools in unloaded conditions is categorized into double ballbar [9,10], crossgrid encoder [11,12], R-test [13,14], laser tracker [15,16], and machine vision technology [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Binocular vision-based 3D method for detecting high dynamic and wide-range contouring errors of CNC machine tools

Li¹,

Liu²,

Pan³

et al. 2019

Meas. Sci. Technol.

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Periodic checking for contouring error in unloading conditions can effectively evaluate the dynamic performance of machining centers. Existing measurement devices have limitations in the high accuracy three-dimensional (3D) measurement of arbitrary contouring errors (e.g. ballbar and cross-grid encoder). Thus, in this paper, a cost-effective binocular vision-based 3D method for detecting high dynamic and wide-range contouring error of computer numerical control machine tools is proposed. With this method, the strobe lighting method is first presented to suppress the blurring effect of the newly designed 1024 coded targets that were embedded in the measurement fixture. Thereafter, an encoding and decoding method based on finding the optimal initial non-encoding region is proposed to automatically identify, match, and reconstruct the time-varying targets. Then, to enhance the performance of the vision system, a calculated method based on three visible non-collinear coded targets is presented to deduce the dynamic and large-scale contouring error. Finally, contouring error detection experiments are carried out in a self-built five-axis machine tool to validate the advantages of the method. Both the proposed vision method and cross-grid encoder are used to measure contouring errors of three types of trajectories under different feed rates. By comparing the difference between the two trajectories measured by the two devices, the experimental results illustrate that the mean vision detection error at 7 m min−1 is about 4.3 µm, which verifies the accuracy and effectiveness of the proposed vision measurement method.

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“…In terms of the ISO 230 series, this year, the ISO/TR 230-11:2018 [5] norm was released to specify the measurement devices suitable for geometry testing of machine tools. To summarize the state-of-the-art ISO standards and research studies, equipment used for dynamic performance assessment under unloaded conditions can be categorized into telescoping ballbar [6,7], cross-grid encoder [8,9], R-test [10,11], laser tracker [12,13] and machine vision technology [14,15,16].…”

Section: Introductionmentioning

confidence: 99%

A Knowledge-Driven Approach for 3D High Temporal-Spatial Measurement of an Arbitrary Contouring Error of CNC Machine Tools Using Monocular Vision

Liu

Pan

et al. 2019

Sensors

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Periodic health checks of contouring errors under unloaded conditions are critical for machine performance evaluation and value-added manufacturing. Aiming at breaking the dimension, range and speed measurement limitations of the existing devices, a cost-effective knowledge-driven approach for detecting error motions of arbitrary paths using a single camera is proposed. In combination with the PNP algorithm, the three-dimensional (3D) evaluation of large-scale contouring error in relatively high feed rate conditions can be deduced from a priori geometrical knowledge. The innovations of this paper focus on improving the accuracy, efficiency and ability of the vision measurement. Firstly, a camera calibration method considering distortion partition of the depth-of-field (DOF) is presented to give an accurate description of the distortion behavior in the entire photography domain. Then, to maximize the utilization of the decimal involved in the feature encoding, new high-efficient encoding markers are designed on a cooperative target to characterize motion information of the machine. Accordingly, in the image processing, markers are automatically identified and located by the proposed decoding method based on finding the optimal start bit. Finally, with the selected imaging parameters and the precalibrated position of each marker, the 3D measurement of large-scale contouring error under relatively high dynamic conditions can be realized by comparing the curve that is measured by PNP algorithm with the nominal one. Both detection and verification experiments are conducted for two types of paths (i.e., planar and spatial trajectory), and experimental results validate the measurement accuracy and advantages of the proposed method.

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Techniques for measuring and compensating for servo mismatch in machine tools using a laser tracker

Cited by 16 publications

References 9 publications

Method of improving large-scale measurement accuracy of laser tracker based on photogrammetry

Method of improving large-scale measurement accuracy of laser tracker based on photogrammetry

Binocular vision-based 3D method for detecting high dynamic and wide-range contouring errors of CNC machine tools

A Knowledge-Driven Approach for 3D High Temporal-Spatial Measurement of an Arbitrary Contouring Error of CNC Machine Tools Using Monocular Vision

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