Abstract
In this paper, we report a method to estimate the friction coefficient of a road surface for humanoids. To estimate the friction coefficient, we invented a foot structure on whose sole a partial slip could occur. We fabricated a foot model with the foot structure and conducted the experiment, in which the load was increased on the foot model on two road surfaces, Non-Oil Surface and Oil Surface, different in the friction coefficient. The distributed forces on the sole was measured by 3-axis force sensors. We found that the ratio of the friction force to the normal force decreased when the friction coefficient decreased. The sole deformation was also measured by a high speed camera and the occurrence of a partial slip was confirmed on both surfaces. We concluded that the magnitude of the friction force was related to the regional stick/slip condition on the contact area.
