# A Framework for Diagnosing Urban Rail Train Turn-Back Faults Based on Rules and Algorithms
## 6 Experiment
### Diagnostic Analysis  
The analysis of the above classifiers is data-oriented and requires a large amount of data. However, through the LDA analysis on the daily report, the maintenance personnel can make rough judgments to better supervise the work of the machine and ensure traffic safety. For the three types of turn-back, LDA analysis produced three tables. According to the previous daily work report, this study extracted ten topics and ten corresponding high-frequency keywords. Domain knowledge in the urban rail field was used to further analyze characteristics of turn-back failures. The LDA mining results of Chinese text are shown in Tables A1-A3 in the Appendix A. Table 5 shows the characteristics of automatic end change (AEC) when this type of turn-back fails. It can be observed from topic 0 that the automatic train supervisory (ATS) system prompts the acceptance of the opening direction during the route. The command is interrupted or disappears. It can be seen from topic 1 that the train must meet the safety envelope and completely enter the platform or the track that meets the automatic terminal change before it meets the conditions of AEC. Combining topic 0 and topic 4, it can be \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & **RF** & **GBDT** & **AdaBoost** & **CART** & **LR** & **SVM (Linear)** & **SVM (Radial)** & **NB** \\ \hline Safe & 0.9509 & 0.9475 & 0.9315 & 0.9509 & 0.9386 & 0.9337 & 0.9500 & 0.9163 \\ PEC & 0.6672 & 0.6927 & 0.6581 & 0.6672 & 0.6523 & 0.6491 & 0.6580 & 0.6228 \\ ATB & 0.7847 & 0.7822 & 0.7639 & 0.7847 & 0.7554 & 0.7543 & 0.7845 & 0.6441 \\ AEC & 0.6442 & 0.6406 & 0.5532 & 0.6442 & 0.5478 & 0.5366 & 0.6233 & 0.3497 \\ Average & 0.7618 & 0.7657 & 0.7267 & 0.7618 & 0.7235 & 0.7184 & 0.7539 & 0.6332 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: F1-score after feature interaction. Figure 6: Feature importance score per class. observed that when the AEC train is in the incoming section, the head end is prone to failure, which can be regarded as the characteristic of AEC failure. Table 6 shows the characteristics of automatic turn-back (ATB). According to topic 0, when the ATS of the ATB train drives downward, the process of rail stop is relatively successful. This may indicate that rail stop failure cannot be used as one of the characteristics in determining whether it is an ATB failure. Topic 1 indicates that during the ATB process, the communication process between the original head-end on-board ATP and CI is consistent with the normal communication process. The original tail-end on-board ATP should confirm that the head-end on-board ATP and CI are successfully deregistered or determine whether the head-end on-board ATP has been disconnected from the CI before sending control information to the CI. Prior to this, the heartbeat information should be sent. At the same time, topic 2 and topic 1 consistently contain heartbeat information. Observing topic 8, it appears that the lights are always on when the train is in the station, and the axle counting logic at the head and tail ends fails. This shows that axle counting failure may be a feature of ATB failure. Table 7 shows the characteristics of point mode end change (PEC). The automatic train operation (ATO) system that appears many times in the table indicates that this is a system where PEC failures often occur in trains. Topic 1 means that the driver presses the down button, the train is inserted into the two down tracks, and the analysis is transferred to the section analysis. Topic 2 indicates that the AR light should be turned on after the on-board ATP judges the automatic terminal swap to be possible. After the AR light is on, the driver presses the \"turn-back\" button, the AR light at the head end flashes, and the MMI display enters the PEC icon. The head-end ATP starts to send the \"returning state\" information to the tail end ATP; send the train position, current mode, and other turn-back-related information to the tail end; and output the parking brake at the same time.