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Fast Measurement and Reconstruction of Large Workpieces with Freeform Surfaces by Combining Local Scanning and Global Position Data.

Chen Z, Zhang F, Qu X, Liang B - Sensors (Basel) (2015)

Bottom Line: With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved.The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry.Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range.

View Article: PubMed Central - PubMed

Affiliation: State Key Lab of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China. cz19902013@sina.com.

ABSTRACT
In this paper, we propose a new approach for the measurement and reconstruction of large workpieces with freeform surfaces. The system consists of a handheld laser scanning sensor and a position sensor. The laser scanning sensor is used to acquire the surface and geometry information, and the position sensor is utilized to unify the scanning sensors into a global coordinate system. The measurement process includes data collection, multi-sensor data fusion and surface reconstruction. With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved. After the dense accurate acquisition of the three-dimensional (3-D) coordinates, the surface is reconstructed using a commercial software piece, based on the Non-Uniform Rational B-Splines (NURBS) surface. The system has been evaluated, both qualitatively and quantitatively, using reference measurements provided by a commercial laser scanning sensor. The method has been applied for the reconstruction of a large gear rim and the accuracy is up to 0.0963 mm. The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry. Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range.

No MeSH data available.


The fitting result comparison: (a) The point data; (b) The conventional method; (c) The proposed method.
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sensors-15-14328-f014: The fitting result comparison: (a) The point data; (b) The conventional method; (c) The proposed method.

Mentions: We adopt the commercial software package Imageware to reconstruct the surface. The NURBS parameters can be calculated and determined by the software automatically. As the number of points improves, the reconstructed surface becomes a better approximation of the true shape. With the use of the combined measurement method, big curvature surfaces can be scanned densely to provide abundant information and then reconstructed with high fidelity. Meanwhile, the fitting skills also have an impact on the accuracy. As shown in Figure 13, there are fillets on the edge. They are produced by the processing technology to remove burrs, reduce the stress concentration and improve the strength of the gear rim. However, with the existence of the fillets, we cannot extract the structural contours for the gear rim. If the curve is reconstructed just by the software automatically, the reconstruction model will show a round corner as shown in Figure 14b. In this paper, each tooth of the gear is divided into two parts. Part 1 is the addendum circle and part 2 includes the left and right flank of a tooth, as shown in Figure 14a. According to the points in the corresponding part, three lines are reconstructed, respectively. Finally, these lines are extended and trimmed in the intersection, as shown in Figure 14c. This method is not only used in the measurement field, but also applied in practical manufacturing.


Fast Measurement and Reconstruction of Large Workpieces with Freeform Surfaces by Combining Local Scanning and Global Position Data.

Chen Z, Zhang F, Qu X, Liang B - Sensors (Basel) (2015)

The fitting result comparison: (a) The point data; (b) The conventional method; (c) The proposed method.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507636&req=5

sensors-15-14328-f014: The fitting result comparison: (a) The point data; (b) The conventional method; (c) The proposed method.
Mentions: We adopt the commercial software package Imageware to reconstruct the surface. The NURBS parameters can be calculated and determined by the software automatically. As the number of points improves, the reconstructed surface becomes a better approximation of the true shape. With the use of the combined measurement method, big curvature surfaces can be scanned densely to provide abundant information and then reconstructed with high fidelity. Meanwhile, the fitting skills also have an impact on the accuracy. As shown in Figure 13, there are fillets on the edge. They are produced by the processing technology to remove burrs, reduce the stress concentration and improve the strength of the gear rim. However, with the existence of the fillets, we cannot extract the structural contours for the gear rim. If the curve is reconstructed just by the software automatically, the reconstruction model will show a round corner as shown in Figure 14b. In this paper, each tooth of the gear is divided into two parts. Part 1 is the addendum circle and part 2 includes the left and right flank of a tooth, as shown in Figure 14a. According to the points in the corresponding part, three lines are reconstructed, respectively. Finally, these lines are extended and trimmed in the intersection, as shown in Figure 14c. This method is not only used in the measurement field, but also applied in practical manufacturing.

Bottom Line: With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved.The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry.Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range.

View Article: PubMed Central - PubMed

Affiliation: State Key Lab of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China. cz19902013@sina.com.

ABSTRACT
In this paper, we propose a new approach for the measurement and reconstruction of large workpieces with freeform surfaces. The system consists of a handheld laser scanning sensor and a position sensor. The laser scanning sensor is used to acquire the surface and geometry information, and the position sensor is utilized to unify the scanning sensors into a global coordinate system. The measurement process includes data collection, multi-sensor data fusion and surface reconstruction. With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved. After the dense accurate acquisition of the three-dimensional (3-D) coordinates, the surface is reconstructed using a commercial software piece, based on the Non-Uniform Rational B-Splines (NURBS) surface. The system has been evaluated, both qualitatively and quantitatively, using reference measurements provided by a commercial laser scanning sensor. The method has been applied for the reconstruction of a large gear rim and the accuracy is up to 0.0963 mm. The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry. Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range.

No MeSH data available.