In order to improve the accuracy of the traditional laser tracking interferometric length measurement method and make the traceability of the datum ruler more reliable, a datum ruler measurement optimization method under multi-attitude is proposed in the paper. The method firstly constructs a multi-attitude datum ruler layout on the basis of traditional laser tracking interferometric length measurement, and collects the measurement information in different datum ruler directions under the layout by a laser tracker, and then adopts the weight-based optimization strategy to optimize the combination of measurement data, and then outputs the measurement results and carries out the analysis of the error source and the evaluation of the uncertainty, and finally conducts experimental analysis on the datum ruler with an accuracy of 1000mm based on the optimization scheme. Finally, based on this optimization scheme, an experimental analysis is carried out on the 1000mm datum ruler, and compared with the CMM method with higher accuracy, the En value is 0.1, which verifies the reasonableness of the uncertainty assessment, and it is found through experimental comparisons that the reference lengths output from the measurement optimization scheme with multiple postures are more reliable than those with single postures. The optimization method provides a new calibration scheme for achieving the traceability of the measurement value of high-precision large-size reference ruler, which has good practicality and certain guiding significance.
A phase correction method based on multi frequency heterodyne principle is proposed for the phase jump error caused by multi frequency heterodyne phase solution. The traditional phase shifting method and multi frequency heterodyne are used to calculate the wrapping phase and the unwrapping phase. Aiming at the jump error in the unwrapping phase, the unwrapping phase is used to locate the error position. The wrapping phase is used as a reference to correct the position of the positioning error to obtain a new unwrapping phase. The experimental results show that under the optimization method, this method can effectively judge the jump, and obtain the unwrapping phase without jump error after eliminating the jump, which greatly improves the unwrapping accuracy and accuracy of the fringe pattern after phase unwrapping.
KEYWORDS: Calibration, Interferometers, Data fusion, Detection and tracking algorithms, Testing and analysis, Visualization, Systems modeling, Standards development, Reliability, Manufacturing equipment
A traceable accuracy test method of multi-instrument cooperative measurement system is studied. Here a precise angle dividing table and a linear guide with a laser interferometer are used as standards to test the cooperative measurement’s external parameters. And the coordinates of common points and uncommon points are tested by the scale bars. This testing method is illustrated with a cooperative measurement system composed of two laser trackers. It is obvious that this method can intuitively test the accuracy of the multi-instrument cooperative measurement’s external parameters and coordinates. This method is not restricted by the measurement principle, the data fusion algorithm and the measurement targets of the cooperative system, and it is suitable for various non-fixed layout cooperative measurement system.
Nowadays most commercial measurement software only indirectly evaluates the accuracy of the cooperative measurement and lacks intuitiveness. Therefore an accuracy evaluation method of the cooperative measurement is studied so that the transformation parameters’ error and the final results’ error in the cooperative measurement are directly quantified. And customized software is developed which is used to quickly and easily evaluate and visually display the accuracy of the cooperative measurement in the industrial field. Finally an experiment with two laser trackers is conducted to prove the accuracy evaluation method and the software of cooperative measurement. It is obvious that the accuracy evaluation method is feasible and the accuracy evaluation software is user-friendly
Most 3D body scanners adopt a structure with multiple scanning sensors on the fixed frame to perform synchronous scanning from multiple directions of the human body. The position and attitude parameters of the multiple scanning sensors are the key to determining the 3D model stitching, and they are often calibrated when the scanner is installed. Any changes in these parameters of sensors will make model stitching errors and affect scanning accuracy. This paper studies a method for judging faults of 3D body scanner based on standard sphere. By scanning a standard sphere and observing the splicing deformation of the 3D model, it can determine whether the scanner's structure has changed, and identify which sensor has moved or rotated. Then the user can be guided to choose the appropriate calibration steps to compensate the scanner. Experiments prove that this method is a quick and effective intermediate check method of the 3D body scanner.
Accurate and traceable reference coordinates in three-dimensional space is the key and difficult point for coordinate calibration of large-scale measurement instruments such as laser tracker and iGPS. This paper studies the application of multilateration with laser tracker in establishing reference coordinates. First, a reference coordinate network is established, which has good spatial scalability and is compatible with multiple targets. Then, multilateration with laser tracker is applied to calibrate the reference coordinate network. And the basic principle, measurement uncertainty evaluation and tracker layout optimization are studied in detail. So that the reference coordinates are traced to the laser interference. Finally, through the repeatability test, length test, and coordinate test, it is shown that the reference coordinates satisfy their measurement uncertainty range and can be used for coordinate calibration of the large-scale measurement instruments.
The network geometry strongly influences the performance of the distributed system, i.e., the coverage capability, measurement accuracy and overall cost. Therefore the network placement optimization represents an urgent issue in the distributed measurement, even in large-scale metrology. This paper presents an effective computer-assisted network placement optimization procedure for the large-scale distributed system and illustrates it with the example of the multi-tracker system. To get an optimal placement, the coverage capability and the coordinate uncertainty of the network are quantified. Then a placement optimization objective function is developed in terms of coverage capabilities, measurement accuracy and overall cost. And a novel grid-based encoding approach for Genetic algorithm is proposed. So the network placement is optimized by a global rough search and a local detailed search. Its obvious advantage is that there is no need for a specific initial placement. At last, a specific application illustrates this placement optimization procedure can simulate the measurement results of a specific network and design the optimal placement efficiently.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.