## 3 Dynamic Prediction of Servo Valve Performance Degradation
### Dynamic Prediction of Performance Indicators
Figure 10:6 Smoothed prediction diagram of pressure gain, leakage dynamic index for condition 10. Figure 10:7 Smoothed prediction diagram of pressure gain, leakage dynamic index for condition 11. Figure 10:8 Dynamic ARIMA prediction diagram of pressure gain, leakage for condition 11. Figure 10:9 Dynamic fusion prediction of pressure gain, leakage for condition 11. Figure 9:0 Smoothed prediction diagram of pressure gain, leakage dynamic index for condition 12. Figure 9:1 Dynamic fusion prediction of pressure gain, leakage for condition 12. Figure 9:2 Smoothed prediction diagram of pressure gain, leakage dynamic index for condition 13. Figure 9:3 Dynamic ARIMA prediction diagram of pressure gain, leakage for condition 13. Figure 9:4 Dynamic fusion prediction of pressure gain, leakage for condition 13. Figure 9:5 Smoothed prediction diagram of pressure gain, leakage dynamic index for condition 14. Figure 9:6 Dynamic ARIMA prediction diagram of pressure gain, leakage for condition 14. Figure 9:7 Dynamic fusion prediction of pressure gain, leakage for condition 14. Figure 9:8 Smoothed prediction diagram of pressure gain, leakage dynamic index for condition 15. Figure 9:9 Dynamic ARIMA prediction diagram of pressure gain, leakage for condition 15. Figure 14:0 Dynamic ARIMA prediction diagram of pressure gain, leakage for condition 14. (MAPE) of pressure gain and leakage predicted dynamically using exponential smoothing 120 s in advance are shown in Tables 3 and 4 below:  
After the key performance indicators are predicted, life prediction can be made based on whether the failure threshold is reached. Because there is no international development and classification of failure standards for direct-drive electro-hydraulic servo valves or even \begin{table}
\begin{tabular}{c c c} \hline \hline
**Condition** & **MAE (L/min)** & **MAPE** \\ \hline
1 & 0.0000004 & 0.0001724 \\ \hline
2 & 0.0001124 & 0.0000907 \\ \hline
3 & 0.0000242 & 0.0000916 \\ \hline
4 & 0.0001263 & 0.0001625 \\ \hline
5 & 0.0000976 & 0.0001533 \\ \hline
6 & 0.0000549 & 0.0001965 \\ \hline
7 & 0.0000140 & 0.0001814 \\ \hline
8 & 0.0000221 & 0.0003369 \\ \hline
9 & 0.0000140 & 0.0001030 \\ \hline
10 & 0.0001004 & 0.0001979 \\ \hline
11 & 0.0000527 & 0.0001917 \\ \hline
12 & 0.0000844 & 0.0002604 \\ \hline
13 & 0.0000241 & 0.0001301 \\ \hline
14 & 0.0001531 & 0.0002039 \\ \hline
15 & 0.0000732 & 0.0000084 \\ \hline
16 & 0.0000760 & 0.0000527 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Prediction error statistics for leakage under the exponential smoothing method. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Condition** & **MAE (MPa/mm)** & **MAPE** \\ \hline
1 & 0.000201 & 0.000325 \\ \hline
2 & 0.000257 & 0.000064 \\ \hline
3 & 0.000245 & 0.000035 \\ \hline
4 & 0.000165 & 0.000149 \\ \hline
5 & 0.000065 & 0.000100 \\ \hline
6 & 0.000269 & 0.000130 \\ \hline
7 & 0.000195 & 0.000089 \\ \hline
8 & 0.000099 & 0.000056 \\ \hline
9 & 0.000282 & 0.000240 \\ \hline
10 & 0.000247 & 0.000128 \\ \hline
11 & 0.000215 & 0.000086 \\ \hline
12 & 0.000183 & 0.000082 \\ \hline
13 & 0.000207 & 0.000050 \\ \hline
14 & 0.000252 & 0.000117 \\ \hline
15 & 0.000300 & 0.000270 \\ \hline
16 & 0.000351 & 0.000202 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Prediction error statistics for pressure gain under exponential smoothing. other control valves, the research in this paper can only be based on the experience of the engineers of the institute that provides direct-drive electro-hydraulic servo valve samples and the requirements of the working environment restrictions in the aerospace industry, usually when the pressure gain is less than 2000 Mpa and the internal leakage is less than 2.5 L/min, wherein it can meet the aerospace servo Valve work requirements. The aim of this paper was therefore also to serve as a pre-requisite study and theoretical guide for the future development of servo valve failure standards in the aerospace sector.