Measurement of dynamic motion of a standing human on a PMV during braking

Abstract

In this study, we focus on a stand-up type personal mobility vehicle (PMV) with three or four wheels that ensures static stability. A PMV is typically compact and lightweight, and the dynamic behavior of the driver affects the dynamics of the entire system. Thus, it is important to investigate the dynamic motion of the driver. Additionally, the difference between the driver’s intentional and unintentional motions should be considered for applying automatic driving or driving assist to a PMV. Therefore, we measured the basic motions of a standing human during braking. Two types of experiments were performed: one using a treadmill to accelerate the static vehicle backward to simulate braking; the other using an actual PMV, with the driver intentionally or unintentionally braking, assuming automatic driving. The experiments demonstrated that by holding the handle when the posture changed owing to braking, the pressure was dispersed from the feet to the side of the handle, and this pressure was equivalent to approximately 30% of the human body weight. In the experiment using a PMV, we observed a significant difference in the drivers’ maximum center of gravity position (COGP) during braking between the with- and without-handle cases, indicating that the center of gravity (COG) movement was significantly suppressed by the handle. However, there was no significant difference in the maximum COGP between the intentional and unintentional braking cases. It was assumed that the driver roughly predicted the braking position owing to the limited experimental space. Furthermore, based on our simulation, it was assumed that the drivers’ upper and lower arm positions had a low impact on the displacement of the drivers’ COGP during braking. These findings can be applied to the modeling of human-PMV systems, and are expected to be useful for designing the forms and dynamic control systems of PMVs.