## 3 Characteristics of Passenger Tolerance to Approaching Pedestrians
### Analysis of Previous Study's Dataset
#### 3.1.3 Factors Affecting Passenger Tolerance  
From the result of Section 2, the factors related to \"Projection of the Future Status\" are suggested to affect passenger tolerance. Therefore, two factors related to a passenger's predictions of discomfort due to the approaching pedestrian were focused on. One factor is the lateral distance between the passenger and the pedestrian when it passes by the PMV. If this is predicted to be long, the passenger can pass by the pedestrian with enough margin and low discomfort. The other factor is the magnitude of the pedestrian's or the  
Figure 4: Passenger discomfort as a function of the PS invasion ratio. Figure 3: Definition of personal space (PS) and the PS invasion ratio. PMV's avoidance behavior toward each other. If this avoidance is predicted to be large, the passenger can pass by the pedestrian with enough margin with low discomfort. The relationships between the two factors and the tolerance metric \(q\) were investigated to examine whether the above factors affect passenger tolerance. Indices representing the two factors were set to investigate the relationships between the two factors and passenger tolerance. The indices were calculated in the vehicle relative coordinate system. The predicted pedestrian behavior in this coordinate system was assumed to be a circular turn with a constant curvature radius, as shown in Figure 5. The predicted pedestrian behavior was calculated based on the position and velocity of the PMV and the pedestrian before the pedestrian invades the passenger's PS. For the first factor, the predicted passing distance \(h\) was set as the distance between the passenger and the intersection point of the predicted pedestrian trajectory and the rear-wheel axle of the PMV. The curvature radius \(R\) of the predicted pedestrian trajectory was set for the second factor. A smaller \(R\) implies a larger change in the pedestrian or the PMV speed, indicating larger avoidance actions. The predicted passing distance \(h\) was calculated for each PS invasion scene, and the relationship between \(h\) and the tolerance metric \(q\) was investigated. As shown in Figure 6, the relationship between \(h\), calculated when the pedestrian was 6.7 m ahead of the PMV, and \(q\) showed a significant positive correlation (\(r\) = 0.58, \(p\) < 0.05). This result suggests that a larger \(h\) makes it easier for passengers to predict that there will be no excessively close approach or collision with the pedestrian, allowing them to tolerate the pedestrian's approach. As for the curvature radius \(R\), the minimum value among the pedestrian conditions in the range 6.0-7.0 m ahead of the PMV was calculated to consider the largest avoidance  
Figure 5: Definition of the predicted passing distance \(h\) and the curvature radius \(R\) of the predicted trajectory. Figure 6: Relationship between the predicted passing distance \(h\) and the tolerance metric \(q\). behavior. As shown in Figure 7, the relationship between \(R\) and the tolerance metric \(q\) showed a significant negative correlation (\(r=-0.71\), \(p<0.05\)). This result indicates that a smaller \(R\) makes it easier for passengers to tolerate the situation. Furthermore, it can be suggested that passengers are more likely to tolerate pedestrian approaches when the curvature radius of the pedestrian's trajectory is small because they can predict significant avoidance movement by either the pedestrian or the PMV and anticipate no collision. From the previous study's dataset analysis, it was suggested that the predicted passing distance and the curvature radius of the predicted pedestrian trajectory affect passenger tolerance. In this dataset, the autonomous PMV actively avoided the surrounding pedestrians. By contrast, suppressing avoidance behavior without compromising passenger discomfort is required to achieve efficient and comfortable movement. Thus, it is necessary to clarify the characteristics of passenger tolerance regarding the factors in cases when the PMV does not perform avoidance behaviors.