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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 error comparison by two methods: (a) The measured object is AC; (b) The measured object is AD.
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sensors-15-14328-f009: The error comparison by two methods: (a) The measured object is AC; (b) The measured object is AD.

Mentions: As the length of AB is too small, we just measure the length of AC and AD by the combined method. Considering that the measurement process is similar, the measurement of AD can be taken as an example to show the measurement process by the combined method. Additional nests are placed for the multi-sensor data fusion between O-XWYWZW and O-XLiYLiZLi. Then, all the measured volumes are separated to two scanning stations. As shown in Figure 7, points A, 1, 2, 3 and 4 are scanned at station 1, and points D, 1, 2, 3 and 4 are scanned at station 2. Meanwhile, points 1, 2, 3 and 4 are measured by the laser tracker as the reference global position points. Based on the principle of the multi-sensor data fusion, the points from both scanning stations can be transferred into the global coordinate system. Finally, we can calculate the length of AD in the global coordinate system. This process is repeated 10 times, and the results are compared with the standard. The deviations are shown in Figure 8. From Figure 9, through the error comparison by two methods for AC and AD, it is clearly observed that the accuracy is improved by the combined method, demonstrating that the combined method is effective to decrease the accumulated error.


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 error comparison by two methods: (a) The measured object is AC; (b) The measured object is AD.
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-14328-f009: The error comparison by two methods: (a) The measured object is AC; (b) The measured object is AD.
Mentions: As the length of AB is too small, we just measure the length of AC and AD by the combined method. Considering that the measurement process is similar, the measurement of AD can be taken as an example to show the measurement process by the combined method. Additional nests are placed for the multi-sensor data fusion between O-XWYWZW and O-XLiYLiZLi. Then, all the measured volumes are separated to two scanning stations. As shown in Figure 7, points A, 1, 2, 3 and 4 are scanned at station 1, and points D, 1, 2, 3 and 4 are scanned at station 2. Meanwhile, points 1, 2, 3 and 4 are measured by the laser tracker as the reference global position points. Based on the principle of the multi-sensor data fusion, the points from both scanning stations can be transferred into the global coordinate system. Finally, we can calculate the length of AD in the global coordinate system. This process is repeated 10 times, and the results are compared with the standard. The deviations are shown in Figure 8. From Figure 9, through the error comparison by two methods for AC and AD, it is clearly observed that the accuracy is improved by the combined method, demonstrating that the combined method is effective to decrease the accumulated error.

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.