## 4 Experimental Analyses  
### Verification Analysis  
To verify the accuracy of the high-speed elevator car air pressure compensation system based on the IE-FF coupling variation model, the law of the air pressure change inside the car is explored through experiments. The 288 m elevator test tower located in CANNY Elevator Co., Ltd. is selected as the experimental site, and the KLK2 (Elevator type of CANNY Elevator Co., Ltd.) ultra-high-speed elevator with a maximum speed of 10 m/s is the experimental object, as shown in Figure 9a. The specific parameters are shown in Table 1.  
To ensure the measurement accuracy of the experimental data, the ZOGLAB DSR-THP temperature, humidity and pressure recorder is selected to record the air pressure changes inside the elevator car during operation. As shown in Figure 9b, the air pressure \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Maximum running velocity (mm/s) & \(1.0\times 10^{6}\) \\ \hline Length of hoistway wall (mm) & \(7.0\times 10^{3}\) \\ \hline Width of hoistway wall (mm) & \(3.45\times 10^{3}\) \\ \hline Area of car (mm\({}^{2}\)) & \(3.48\times 10^{6}\) \\ \hline Height of car (mm) & \(3.0\times 10^{3}\) \\ \hline Shape of diversion cover & Semicircle \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameters of the KLK2 ultra-high-speed elevator. Figure 9: Experimental instruments. (**a**) 288 m elevator test tower in Canny; (**b**) ZOGLAB DSR-THP temperature, humidity and pressure recorder; and (**c**) PMT-EVA625 elevator comprehensive performance tester. measurement range is 500-1100 hPa. The measurement accuracy can reach \(\pm\)0.5 hPa. The PMT-EVA625 elevator comprehensive performance tester is selected to record the elevator running speed and lifting height in real time, as shown in Figure 9c. The amplitude of the air pressure changes during the elevator up and down the process is the same; only the direction of change is the opposite. In addition, when the elevator goes down, the external pressure gradually increases, the negative pressure forms in the tympanum. The eustachian tube presents a one-way valve like effect, and it is difficult to open due to the influence of the surrounding high pressure. The external gas cannot enter the tympanum, resulting in a sense of pressure in the ear. On the contrary, when the elevator goes up, there is a slight swelling in the eardrum. Since the human ear is more sensitive to pressure, the down process of the elevator is selected as the elevator operating condition to measure and analyze. Three sets of experimental data by changing the maximum operating speed and maximum lifting height of the elevator are obtained, as shown in Table 2.  
For the first two sets of data, because the departure height is above 200 m, the changes of the air pressure inside the car are large during elevator operation, so passengers have ear pressing twice. For the third set of experimental data, the departure height is lower, and passengers only experience ear pressing once, and the duration is shorter than the previous two experiments during elevator operation. Therefore, it can be preliminarily concluded that the ear comfort of passengers has a greater relationship with the elevator lifting height during high-speed elevator operation. There are two ear pressing durations in the elevator running process in first and second experiment. In the third experiment, descent distance is only 110 m. There is no not enough distance for a second ear pressing. According to the results obtained from the experiment and the results calculated from the proposed method, the measured air pressure curves at the same height and different speeds, and the measured pressure value curves at the same speed and different heights are, respectively, drawn as shown in Figure 10a,b. Based on the established IE-FF coupling variation model, the air pressure value curve obtained by the proposed method inside the car through the coupled iterative calculation is as shown in Figure 10a,b.