## 5 Automatic Parking Test of Real Vehicle
The other is the medium parking slot on the right side with a length of 5.6 m (i.e., vehicle length + 0.9 m), which is composed of the front and rear obstacle with the curbstone. In addition, Figure 24 shows the parking scenario for the automatic parking test. Figure 21: Real Vehicle Test Equipment. We carried out the automatic parking tests with the side distance of 0.5 m\(\sim\)1.5 m. We chose five side distances of 0.5 m, 0.8 m, 1.0 m, 1.3 m and 1.5 m for the parking test, and five parking tests were carried out with each side distance continuously. We used the automatic parking system performance evaluation method to record all test data [36, 37, 38]. Tables 2 and 3 show the automatic parking evaluation index, evaluation criteria and test data of the above standard parking slot and medium parking slot, respectively. Note: the item with gray background in the table refers to the failed item. Figure 23: Actual Path Tracking Effect. Figure 22: Rear Axle Midpoint Trajectory. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multicolumn{6}{c}{**Searching Performance**} & \multicolumn{3}{c}{**Parking Efficiency**} & \multicolumn{3}{c}{**Parking Position \& Attitude**} & \multicolumn{3}{c}{**Result**} \\ \hline \multirow{2}{*}{**Index**} & **Side** & **Search** & **Search Result** & **Parking** & **Number of** & **D-Value** & **Distance Front** & **Distance Rear** & **Parking** & **1: Success** \\  & **Distance** & **Speed** & **1:Y 0:N** & **Time** & **Gear Shifts** & **Front to Rear** & **Wheel to Curb** & **Wheel to Curb** & **Angle** & **0: Fail** \\ \hline
**Unit** & **m** & **km/h** & & **s** & & **mm** & **mm** & **Mm** & **deg** & \\ \hline
**Criteria** & **0.5-1.5 m** & **10** & & \(\leq\)**60** & \(\leq\)**6** & \(\  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multicolumn{6}{c}{**Searching Performance**} & \multicolumn{4}{c}{**Parking Efficiency**} & \multicolumn{4}{c}{**Parking Position \& Attitude**} & \multicolumn{1}{c}{**Result**} \\ \hline \multirow{2}{*}{**Index**} & **Side** & **Search** & **Search Result** & **Parking** & **Number of** & **D-Value** & **Distance Front** & **Distance Rear** & **Parking** & **1: Success** \\  & **Distance** & **Speed** & **1:Y; 0:N** & **Time** & **Gear Shifts** & **Front to Rear** & **Wheel to Curb** & **Wheel to Curb** & **Angle** & **0: Fail** \\ \hline
**Unit** & **m** & **km/h** & & **s** & & **mm** & **mm** & **mm** & **deg** & \\ \hline
**Criteria** & **0.5-1.5 m** & **10** & & \(\leq\)**60** & \(\leq\)**6** &  
Based on the 50 times parking experiment data and the evaluation criteria, the number of both successful and failed parking operations, as well as the reason of parking failure were obtained. The success rate of parking is 90%. Besides, there are two times/types of parking failure caused searching failure of the parking slot. The real parking success rate can reach 93.75% by removing the data of the two times/types of failure. Since the content of this paper does not involve the study of the parking slot search algorithm, instead of the failure analysis of the search, only the cause of the parking failure based on path planning and tracking control is analyzed. By analyzing the real-time bus data collected during the parking process, it is concluded that there are two reasons for the parking failure. First, the deviation from the curbstone data detected by the long-distance ultrasonic radar and the real curbstone distance is more than \(\pm\)8 cm. This may result in the deviations in the parking path planning, and in turn lead to too low or too high distance between the wheel and the curbstone when the parking is completed, that is, the above distance exceeds the distance limit of 10 cm\(\sim\)25 cm from the wheel to the curbstone required by the parking success standard. Second, due to the long driving distance in the parallel parking process, there are accumulated wheel speed pulse errors, steering wheel angle errors, and wheel slip during steering.