# Research on the Crane Safety Assessment Method Based on the Cloud Model and ICWGT
## 4 Discussion and Conclusions  
### Discussion  
According to the cloud model and cloud images of crane fuzzy comprehensive assessment results, based on the cloud model and ICWGT, the expected value of the cloud model of the known boom system assessment results is \(Ex=0.814\), which is the center value of the results. The safety assessment level of each subsystem is consistent with that of the whole machine. Therefore, according to Table 4, the expected value of the boom system is (0.75, 0.85), and the corresponding assessment level is II. By analyzing the cloud morphology  
Figure 5: The cloud images of the assessment results: (**a**) the boom system; (**b**) the herringbone system; (**c**) the gantry system; (**d**) the turntable column system; (**e**) other structures; (**f**) the complete machine system. \begin{table}
\begin{tabular}{c c} \hline \hline
**System** & **Assessment Result** \\ \hline Boom & \(V_{\text{P}_{1}}(0.814,0.095,0.093)\) \\ Herringbone & \(V_{\text{P}_{2}}(0.763,0.082,0.081)\) \\ Gantry & \(V_{\text{P}_{3}}(0.813,0.092,0.087)\) \\ Turntable column & \(V_{\text{P}_{4}}(0.794,0.088,0.089)\) \\ Other structures & \(V_{\text{P}_{6}}(0.884,0.094,0.094)\) \\ Complete machine & \(V_{\text{P}}(0.811,0.153,0.150)\) \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The cloud model of the assessment results. thickness and cloud droplet dispersion in Figure 5a, it can be seen that cloud droplets are mostly concentrated in the level V2 region, and a small number of cloud droplets are distributed in the level V1 region. Therefore, it is concluded that the safety level of the boom system is II. This assessment result indicates that the metal structure of the boom system is in good condition. Using the same judging method, it can be established that the safety level of the herringbone frame system is II, the safety level of the portal frame system is II, the safety level of the turntable column system is II, and the safety level of other structures is I. For the whole system, the index assignment is the assessment result cloud model of each subsystem, so the fuzzy relationship matrix of the complete machine system \(R_{P}\) is obtained according to the calculation results of each subsystem in Table 8. Then, the expected value of the complete machine system assessment results is calculated to be \(Ex=0.805\). According to Table 4, the expected value of the complete machine system is (0.75, 0.85), and the corresponding assessment level is II. By analyzing the cloud morphology in Figure 5f, it can be concluded that the metal structure safety level of the crane is II, which means that the shipyard portal crane is in good condition and it is recommended to strengthen maintenance. The assessment results are compared with those obtained by the fuzzy analytic hierarchy process (FAHP), the method approximating the ideal solution ordering, and ICWGT combined with gray correlation analysis. The comparison of the results is shown in Table 9.  
As shown in Table 9, the FAHP used in the literature [21] is to judge the safety level of the crane using the calculated level characteristic values, and the final assessment results of the crane depend on the range in which the level characteristic values are located. Approximating the ideal solution ordering method used in the literature [23] judges the safety level of the crane based on the ranking of the combined prospect values. The ICWGT, combined with the gray correlation analysis method, used in the literature [26] gives the results of the crane safety assessment by a more accurate description of the stage change trend of the crane's safety condition, based on the calculated results. However, these three methods evaluate the sample values only through theoretical calculations to obtain the assessment results and have the problem of not being able to accurately describe the safety condition of the crane.