## 1 Introduction  
Currently, automobiles play a crucial role in daily activities, such as shopping. However, accidents involving older drivers in Japan have become a social issue, leading some individuals to voluntarily give up their driver's licenses. Consequently, with the increasing population aging, there is a growing need for mobility support to assist the daily lives of older people. Therefore, personal mobility vehicles (PMVs), such as mobility scooters, are considered a means of mobility support. However, accidents resulting from user errors and misjudgments in operation have been reported [1]. Accordingly, developing autonomous functions independent of the users' abilities is crucial; ongoing efforts are being made in this direction [2; 3; 4].  
In contemplating the societal implementation of autonomous PMVs in pedestrian spaces, it is important to consider not only the ability of the individual to reach their destination safely but to move efficiently and comfortably [5]. This efficiency can be interpreted as \"short travel time to the destination\". In a study investigating the travel time of autonomous vehicles, the \"Freezing Robot Problem\" was identified. This problem indicates the significant increase in travel time when mobility comes to a halt or takes extensive detours in crowded environments where a wide margin is maintained between pedestrians [6]. On the other hand, studies regarding the comfort of autonomous vehicles have investigated the comfort of both passengers and pedestrians in pedestrian spaces. Approaches to improve comfort focus on the relationship between passenger comfort and factors such as acceleration and jerk [7]. Furthermore, a concept exists known as personal space (PS), where humans feel discomfort when that space is invaded by others. PS influences the comfort of passengers and pedestrians [8]. Based on this concept, previous studies have proposed methods to make autonomous movement comfortable for passengers and pedestrians [9; 10].  
There is a trade-off relationship between efficiency and comfort in crowded environments where pedestrians and PMVs approach each other. The PS concept suggests that PMVs should make significant avoidance behavior to obtain comfort. However, the larger the avoidance behavior, the longer the travel time. Considering this relationship, [PERSON] et al. [11] explored effective avoidance strategies for autonomous PMVs from the perspectives of both pedestrians' comfort and PMV's travel time. However, to achieve socially acceptable movement, it is also essential to consider passenger comfort.  
In crowded environments where the invasion of a passenger's PS by surrounding pedestrians is unavoidable, PMV passengers do not necessarily feel increased discomfort due to approaching pedestrians. Such instances can be viewed as situations where passengers tolerate invasion into their PS. If the characteristics of passenger tolerance (e.g., situations where passenger discomfort is relatively small concerning approaching pedestrians) are clarified, autonomous PMV movement satisfying both efficiency and comfort can be achieved. Therefore, this study aims to clarify the characteristics of passenger tolerance and propose a path-planning method considering the clarified characteristics, which can achieve efficient autonomous navigation without increasing passenger discomfort.  
The remainder of this paper is organized as follows. Section 2 describes passenger tolerance to approaching pedestrians. Section 3 shows an investigation of its characteristics. Section 4 describes the proposed path-planning method considering the passenger tolerance characteristics. Section 5 shows the validation of the proposed method. Lastly, Section 6 summarizes the findings of this study.