scholarly journals Modeling and Analysis of System Error for Highly Curved Freeform Surface Measurement by Noncontact Dual-Axis Rotary Scanning

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 554
Author(s):  
Li Miao ◽  
Linlin Zhu ◽  
Changshuai Fang ◽  
Ning Yan ◽  
Xudong Yang ◽  
...  
Keyword(s):  
High Precision ◽  
Measurement Accuracy ◽  
Rotation Axis ◽  
Optical Probe ◽  
Measuring System ◽  
Freeform Surface ◽  
Normal Vector ◽  
Profile Measurement ◽  
Freeform Surfaces ◽  
System Error

Profile measurement is a key technical enabler in the manufacturing of highly curved freeform surfaces due to their complex geometrical shape. A current optical probe was used to measure nearly rotary freeform surfaces with the help of one rotation axis, because the probe needs to measure along the normal vector of the surface under the limitation of the numerical aperture (NA). This kind of measuring system generally has a high cost due to the high-precision, multi-axis platform. In this paper, we propose a low-cost, dual-axis rotation scanning method for a highly curved freeform surface with an arbitrary shape. The optical probe can scan the surface profile while always keeping consistent with the normal vector of the measuring points with the help of the double rotation axis. This method can adapt to the changes in curvature in any direction for a highly curved freeform surface. In addition, the proposed method provides a system error calibration technique for the rotation axis errors. This technique can be used to avoid the dependence of the measuring system on the high-precision platform. The three key system errors that affect the measurement accuracy such as installation error of the B-axis, A-axis, and XZ perpendicularity error are first analyzed through establishing an error model. Then, the real error values are obtained by the optimal calculation in the calibration process. Finally, the feasibility of the measurement method is verified by measuring one cone mirror and an F-theta mirror and comparing the results to those obtained using commercial equipment. The maximum measurable angle of the system is ±90°, the maximum measurable diameter is 100 mm, and the measurement accuracy of the system reaches the micron level in this paper.

Error Modeling and Compensation for High-Precision Non-Contact Four Coordinate Measuring System

2010 ◽  
Vol 437 ◽  
pp. 232-236 ◽  
Author(s):  
Fei Zhang ◽  
Zhuang De Jiang ◽  
Bing Li ◽  
Jian Jun Ding ◽  
Lei Chen
Keyword(s):  
High Precision ◽  
Error Compensation ◽  
Rotation Axis ◽  
Thermal Error ◽  
Geometric Error ◽  
Error Modeling ◽  
Measuring System ◽  
Precision Measuring ◽  
Compensation Methods ◽  
Compensation Technique

The error compensation technique is used to improve the accuracy of non-contact high-precision measuring system. To ensure the accuracy of the high-precision non-contact four-coordinate blade profile measuring system, the geometric and thermal error compensation model is proposed in this paper. The system is composed of three orthogonal coordinate axes (X, Y and Z) and a rotation axis R. The coordinate transformation matrix can be calculated by the mathematical model of rigid body which is established according to the related theoretical analysis. Three-beam interferometer and standard gauge block are adopted to verify the geometric error of the system. In the thermal deformation error compensation, wavelet neural network model is established. The thermal and geometric error compensation methods are analyzed and the experimental results are given.

On-Machine Optical Surface Profile Measuring System for Nano-Machining

2011 ◽  
Vol 5 (3) ◽  
pp. 369-376 ◽  
Author(s):  
Hiroshi Sawano ◽  
◽  
Motohiro Takahashi ◽  
Hayato Yoshioka ◽  
Hidenori Shinno ◽  
...  
Keyword(s):  
Error Detection ◽  
Machine Surface ◽  
Detection Method ◽  
Surface Profile ◽  
Optical Probe ◽  
Measuring System ◽  
Profile Measurement ◽  
Optical Surface ◽  
Increasing Demand ◽  
Surface Profile Measurement

There has been an increasing demand for machining of precision parts recently. In order to meet such requirements, nano-machining systems with on-machine surface profile measuring function are required. This paper presents a newly developed on-machine shape measuring system with an optical probe. In this system, an astigmatic focus error detection method is applied to the optical probe. In addition, the influence of the uneven reflection from the surface can be reduced by using two quadrant photodiodes. The results of surface profile measurement confirm that the system developed provides a resolution of 1 nm scale and a repeatability of approximately 50 nm.

Profile Measurement of a Curved Workpiece by the Fuzzy Control of Sensor Positioning

1999 ◽  
Author(s):  
Masatake Shiraishi ◽  
Gongjun Yang
Keyword(s):  
Fuzzy Control ◽  
Control Algorithm ◽  
Experimental Results ◽  
Measuring System ◽  
Displacement Sensor ◽  
Profile Measurement ◽  
Laser Displacement Sensor ◽  
Inclination Angles ◽  
Fuzzy Control Algorithm ◽  
Sensor Positioning

Abstract A laser displacement sensor which has a resolution of 0.5 μm was used to determine the measurement of a curved workpiece profile in turning. This sensor is attached to a specially designed stage and is operated by three motors which are controlled by a fuzzy control algorithm. The experimental results show that the measuring system can be applied to workpieces having inclination angles of up to around 45°. The proposed measuring system has a practical measuring accuracy to within ten micrometers.

scholarly journals A Novel Vision-Based Pose Measurement Method Considering the Refraction of Light

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4348 ◽  
Author(s):  
Wei Liu ◽  
Xin Ma ◽  
Xiao Li ◽  
Yi Pan ◽  
Fuji Wang ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Measurement Accuracy ◽  
Performance Testing ◽  
Angle Measurement ◽  
Normal Vector ◽  
Calibration Model ◽  
Linear Calibration ◽  
Observation Window ◽  
Vision Measurement

Nowadays, due to the advantages of non-contact and high-speed, vision-based pose measurements have been widely used for aircraft performance testing in a wind tunnel. However, usually glass ports are used to protect cameras against the high-speed airflow influence, which will lead to a big measurement error. In this paper, to further improve the vision-based pose measurement accuracy, an imaging model which considers the refraction light of the observation window was proposed. In this method, a nonlinear camera calibration model considering the refraction brought by the wind tunnel observation window, was established first. What’s more, a new method for the linear calibration of the normal vector of the glass observation window was presented. Then, combining with the proposed matching method based on coplanarity constraint, the six pose parameters of the falling target could be calculated. Finally, the experimental setup was established to conduct the pose measurement study in the laboratory, and the results satisfied the application requirements. Besides, experiments for verifying the vision measurement accuracy were also performed, and the results indicated that the displacement and angle measurement accuracy approximately increased by 57% and 33.6%, respectively, which showed the high accuracy of the proposed method.

Study on Profile-Adaptive Tool System for Small Robots in Large Freeform Surface Polishing

2010 ◽  
Vol 37-38 ◽  
pp. 1327-1331
Author(s):  
Qi Tong Liu ◽  
Jian Ming Zhan ◽  
Jian Hua Mao
Keyword(s):  
Freeform Surface ◽  
Polishing Process ◽  
Processing Efficiency ◽  
Kinematic Equation ◽  
Freeform Surfaces ◽  
Surface Polishing ◽  
Adaptive Tool

An adaptive tool system of polishing robots for large freeform surface which is installed discoid tool is proposed. To improve processing efficiency, the mechanical of adaptive tool system adjust to curvature changing of large freeform surface is designed. Adaptability of the processing is analyzed and simulated, and kinematic equation of tool system is established. The polishing process of large freeform surfaces with tool system is analyzed.

scholarly journals Cosine Error-Free Metrology Tool Path Planning for Thickness Profile Measurements

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Xiangyu Guo ◽  
ChaBum Lee
Keyword(s):  
Path Planning ◽  
Wall Thickness ◽  
Tool Path ◽  
Measuring System ◽  
Profile Measurement ◽  
Thin Wall ◽  
Tool Path Planning ◽  
Thickness Profile ◽  
Thin Walls ◽  
Displacement Sensors

Abstract This paper presents a novel thickness profile measuring system that measures double-sided thin pipe wall surfaces in a non-contact, continuous, cosine error-free, and fast manner. The surface metrology tool path was developed to align the displacement sensors always normal to the double-sided surfaces to remove cosine error. A pair of capacitive-type sensors that were placed on the rotary and linear axes simultaneously scans the inner and outer surfaces of thin walls. Because the rotational error of the rotary axis can severely affect the accuracy in thickness profile measurement, such error was initially characterized by a reversal method. It was compensated for along the rotational direction while measuring the measurement target. Two measurement targets (circular and elliptical metal pipe-type thin walls) were prepared to validate the developed measurement method and system. Not only inner and outer surface profiles but also thin-wall thickness profiles were measured simultaneously. Based on the output data, the circularity and wall thickness variation were calculated. The thickness profile results showed a good agreement with those obtained by a contact-type micrometer (1-µm resolution) at every 6-deg interval. The uncertainty budget for this measuring system with metrology tool path planning was estimated at approximately 1.4 µm.

A weighted fusion method with multi-system for improving measurement accuracy of structured light 3D profilometry

2021 ◽  
Author(s):  
Chao Xing ◽  
Junhui Huang ◽  
Zhao Wang ◽  
Jianmin Gao
Keyword(s):  
Measurement Errors ◽  
Measurement Accuracy ◽  
Structured Light ◽  
Profile Measurement ◽  
Complex Surfaces ◽  
3D Profilometry ◽  
Weighted Fusion ◽  
Multiple Measurements ◽  
Geometric Relationship ◽  
3D Profile

Abstract It is a challenge to improve the accuracy of 3D profile measurement based on binary coded structured light for complex surfaces. A new method of weighted fusion with multi-system is presented to reduce the measurement errors due to the stripe grayscale asymmetry, which is based on the analysis of stripe center deviation related to surface normal and the directions of incident and reflected rays. First, the stripe center deviation model is established according to the geometric relationship between the stripe center deviation, the incident and reflected angles at any measured point. The influence of each variable on stripe center deviation is analyzed, and three subsystems are formed by a binocular structured light framework to achieve multiple measurements based on the influence regularity. Then in order to improve the measurement accuracy, different weights are assigned to the measured point in different subsystems according to the stripe center deviation model and its relationship with measurement error, and the weighted data from different subsystems are fused. Experiments are carried out to validate the presented method, and the experimental results demonstrate that it effectively improves the measurement accuracy of complex surfaces and measurement accuracy is improved by about 27% compared with the conventional method.

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