Obstacle Avoidance Capability of a Personal Mobility Vehicle (PMV) with an Inward Tilting Mechanism under Braking Conditions

This study delves into the dynamics of three-wheeled Personal Mobility Vehicles (PMVs) equipped with an active tilting mechanism. In three-wheeled vehicles with a single front wheel, the risk of tipping over during sudden braking and sharp turning is often highlighted. To address this issue, the authors have focused their research on three-wheeled PMVs with two front wheels and one rear wheel, equipped with an active tilting mechanism. Previous studies using dynamic simulation tools have demonstrated that such PMVs possess higher obstacle avoidance capabilities compared to motorcycles and even passenger cars. However, these simulations were based on the assumption of avoidance maneuvers without braking, and no studies have yet examined the behavior of three-wheeled PMVs with an active tilting mechanism under the more complex conditions of braking during turning. Therefore, prior to conducting dynamic simulations under braking and turning conditions, this study aims to clarify the mechanical equilibrium conditions under these circumstances. It identifies the limits of braking deceleration and turning lateral acceleration based on tipping conditions and examines the changes in tire vertical loads during braking and turning, which influence the upper limits of tire force generation. The organization of the mechanical equilibrium conditions during braking and turning is carried out in the following steps: 1. Four-wheeled vehicles: No significant difference in front and rear tread widths, and no tilting. 2. Three-wheeled PMVs: Zero rear tread width, and no tilting. 3. Three-wheeled PMVs: Zero rear tread width, and tilting during turning. Future dynamic analyses will rely on evaluations using dynamic simulation models. These analyses will take into account not only dynamic factors such as vehicle inertia but also the significant influence of actively controlled tilting behavior, as previously demonstrated by studies using dynamic simulation tools. In this study, the validity of the mechanical equilibrium analysis is confirmed through simplified dynamic simulations. Based on this validation, the study identifies key points to focus on in future detailed dynamic behavior analyses.