Analytical Description of Benchmark Plane Assists in Laser Tracker Station Transfer Precision Control

The laser tracker station transfer of a benchmark plane is often required in large-scale structural assembly, such as ship-block alignment, to maintain global geometric consistency. The purpose of station transfer is to extend the main benchmark plane to the immediate working regions. The conventional method is to set up several sub-benchmark points according to the main plane; however, this can cause positioning errors due to structural thermal deformation, etc. To address this problem, this paper proposes a method to describe the benchmark plane as an analytical equation, by which the station transfer can be realized through four convenient common points without the need of any physical sub-benchmark point. Thus, precision is improved due to the avoidance of errors originating from the sub-benchmark points. The objective of this study is to compare the accuracy of the two methods. We employed a specific distance between the main benchmark plane and the target transferred plane to evaluate the performance of both methods. The experimental results showed that the distance error is 0.220 mm for the conventional method and 0.036 mm for the proposed method. This proves that the proposed method can effectively assist in station transfer.