# Evaluation of the Large-Length Indoor Standard Installation Based on Single Point Scanning
## 6 Conclusions  
In this study, the laser tracker method based on single point scanning was proposed to evaluate the accuracy of the LLISI. The laser tracker, as a method of measuring the LLISI, can achieve high measuring accuracy, high repeatability and large space measurement. Otherwise, the proposed method is able to dynamically collect 3D point cloud data in real time and has been used to provide a higher measurement accuracy.  
Under the standard experimental environment, the measurements were carried out at measurement intervals of 0.1 m, 0.3 m, 0.5 m, 1.0 m and 5.0 m and at 50 mm/s, 100 mm/s and 150 mm/s, respectively. The measurement results of the laser tracker were compared with that of the laser interferometer through single and multiple measurements under the case of indoor large-scale measurement. The maximum time and average time in  
\begin{table}
\begin{tabular}{c l l l l l} \hline \hline \multicolumn{1}{c}{**No.**} & \multicolumn{1}{c}{**Measurement Uncertainty**} & \multicolumn{1}{c}{**Values**} & \multicolumn{1}{c}{**No.**} & \multicolumn{1}{c}{**Measurement Uncertainty**} & \multicolumn{1}{c}{**Values**} \\  & \multicolumn{1}{c}{**Components**} & & & & & \\ \hline
1 & Range measurement & 11.45 \(\mathrm{\SIUnitSymbolMicro m}\) & 4 & Measurement environment & 0.3 \(\mathrm{\SIUnitSymbolMicro m}\) \\  & repeatability of the laser tracker & (\(k\) = 1) & & & (\(k\) = \(\sqrt{3}\)) \\
2 & Measurement uncertainty of the & 0.4 \(\mathrm{\SIUnitSymbolMicro m}\) & 5 & Error of the center of the optical & 0.5 \(\mathrm{\SIUnitSymbolMicro m}\) \\  & laser tracker & (\(k\) = 2) & & target mirror & (\(k\) = 2) \\
3 & Reading drift of the laser tracker & 0.12 \(\mathrm{\SIUnitSymbolMicro m}\) & 6 & Collection time of the laser tracker & (\(k\) = 2) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Sources of measurement uncertainty.  
the movement period under different measurement intervals and nominal speeds were quantified. Hence, it is distinctly shown that the proposed method has the advantage of high insensitivity to noise. In addition, the evaluation method of measurement uncertainty was employed to evaluate the results of the local velocity of the LLISI measured by the proposed method. When the value of a confidence factor is \(k=2\), the uncertainty of the local measurement speed of the laser tracker was approximatively 0.23 mm/s evaluated in accordance with the measurement uncertainty standards. The results showed that the laser tracker has the features of minor errors, low data dispersion, and superior repeatability.  
In summary, the proposed method has a high accuracy greater potential capacity in the single measurement and can be used utilized to provide support for data resource protection and health management of the LLISI. However, the large capacity of sampling data has introduced the challenge of processing data to influence the real-time result of evaluating the LLISI. For ensuring to rapidly and accurately estimate the operating state of the LLISI, the intelligent optimization algorithms will be significantly taken into account to process and analyze the measurement data in the follow-up research work.  
[PERSON] and [PERSON] designed the experiments, [PERSON] ([PERSON]) and [PERSON] helped to perform measurements; [PERSON] and [PERSON] wrote the paper, [PERSON], [PERSON] and [PERSON]. ([PERSON]) revised the paper [PERSON] applied for the funding and managed the project. All authors have read and agreed to the published version of the manuscript.  
The research was funded by the National Natural Science Foundation of China (61604154, 61875201, 61975211, 62005287), and the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2021380).  
Not applicable.  
Data Availability Statement: Data is contained within the article.  
The authors declare no conflict of interest.