Abstract
One of the risk factors for falls in visually impaired persons is difficulty to recognize a change of road surface slipperiness by white cane. Therefore, we propose a detector system of slipperiness change by measuring a coefficient of static friction between the white cane and road surface using the white cane with force sensor and inertial sensor. However, when the white cane knocks road surface, impulsive force acting on the white cane makes estimating the coefficient of static friction difficult. Therefore, we investigated a minimum time interval between knocking road surface and starting sliding the white cane that can estimate the slipperiness change by the coefficient of static friction, because the impulsive force decrease as the time interval increases. We measured and compared the coefficient of static friction of three road materials at different time intervals using an equipment swing and sliding the white cane. The result suggested that the slipperiness change which have the fall risk can be estimated, when the time interval is 0.10[s] and over.
