Projective Parallel Single-Pixel Imaging to Overcome Global Illumination in 3D Structure Light Scanning

International Conference on Optical and Photonic Engineering (icOPEN 2022)

et al. 2023

High-accuracy 3-D shape measurement of turbine blade is important for manufacturing engine and aircraft's safety. At present, the most commonly used three-coordinate measuring machine in the industrial field may cause scratches on the surface of turbine blade. Optical 3-D measurement methods, such as fringe projection profilometry, are unable to carry out targeted measurement of geometric structures with different levels of precision. This paper presents an automatic measurement method based on pneumatic gripper and 6-axis robot. The proposed composite system includes global sensor with large scanning range and local sensor with high accuracy, which can perform 3-D reconstruction with specific resolution for different positions of turbine blade. We use a 6-axis robot and pneumatic gripper to grasp the turbine blade automatically. The 3-D scanning is completed according to the viewpoints planned in advance. The point cloud data of different angles are aligned to obtain a high precision 3-D model of turbine blade surface. The experimental results show that the proposed automatic scanning method can effectively avoid the measurement error caused by manual grasping operation. On the basis of complete 3-D measurement of the whole surface, more dense point cloud data are obtained for fine structures such as blade edge. Our result is of great significance to the field of industrial measurement.

Section: Composite Optical Measurement Methodsmentioning

confidence: 99%

An automated 3D shape measurement method for turbine blade using a 6-axis robot

Wang

International Conference on Optical and Photonic Engineering (icOPEN 2022)

et al. 2023

“…1), and is implemented by three stages. The first stage is the localization stage, where the visible region of each pixel in the FPA is localized by adaptive regional SI on the basis of Fourier slice theorem [18], [19].…”

Section: Introductionmentioning

confidence: 99%

Robustness analysis of parallel single-pixel imaging

International Conference on Optical and Photonic Engineering (icOPEN 2022)

et al. 2023

Single-pixel imaging (SI) methods have been widely studied in recent years. However, most existing researches have illustrated SI as an attractive prospect when multipixel sensors are not preferable due to cost or technological constraints. Parallel single-pixel imaging (PSI) has been introduced recently such that SI techniques is also attractive when multipixel sensors are easily obtained and provides new possibilities to traditional challenging problems. By treating each pixel on the camera as an independent SI unit, PSI captures light transport coefficients (LTCs) in highly efficient manner, and separates direct illumination and global illumination, thereby enabling 3D reconstruction under global illumination. Localization stage is of great importance for PSI, where the approximate information for visible region is obtained. In this paper, we analyze the robustness property of PSI with respective to localization stage. Robustness property of PSI states that the accuracy of 3D reconstruction data by PSI is insensitive to errors incurred in the localization stage. Firstly, we show this property from a theoretically aspect. Then, we conduct two experiments to test this property. Lastly, we also show that satisfactory 3D reconstruction results can be obtained when only partial frequencies are captured in the localization stage for a higher efficient data capture procedure.

“…To reconstruct the 3D data of step edges quickly and accurately is a significant challenge in 3D measurement. Active non-contact 3D surface measurement techniques such as fringe pattern profilometry (FPP) [1] and parallel single-pixel imaging [2] are applicable to the manufacturing industry. FPP is one of the most widely used techniques in practical applications of 3D shape measurements due to its high efficiency and precision [3].…”

Section: Introductionmentioning

confidence: 99%

An error compensation method for 3D measurement of step edge in fringe projection profilometry

Wang

International Conference on Optical and Photonic Engineering (icOPEN 2022)

et al. 2023

Fringe projection profilometry is an efficient, fast and non-contact 3D measurement technique, widely used in industrial parts measurement. However, invalid phases are common when measuring step edges such as holes, ribs and steps in industrial parts which leads to outliers in reconstructed point cloud and ultimately causes reduction of valid point cloud and dimensional measurement errors. In this paper, an error compensation method on 3D measurement of step edge is proposed. 3D measurement space is firstly divided into multiple subspaces based on binocular camera system parameters. Then a calibration method is proposed to calculate the amount of compensation for each subspace and obtain parameters of edge error model. After calibration, point cloud of object with step edge is reconstructed by projecting phase-shifting structured light fringe patterns. By using Principal Component Analysis (PCA), normal estimation of point cloud is implemented. And edge feature is extracted with combination of eigenvalues variation of the covariance matrix and first-and second-order fitting based on two-dimensional projection. At the same time, the corresponding deviation amount of each edge point is solved on the basis of aforementioned edge error model. Finally, the accurate step edge is obtained after error compensation according to the normal direction and deviation amount. Experimental results show that, the method proposed can effectively improve the 3D measurement accuracy of step edge.