Planar sliding analysis of a biped robot in centroid acceleration space

In this paper, a two-dimensional analysis of biped robot sliding dynamics is considered. First, the dynamics of a biped robot based on feet slip are derived using the Coulomb friction model. The state transition can be formulated in the centroid acceleration space whose diagram is defined as a “triangle of sliding friction.” The triangle of sliding friction´s characteristics are explained by focusing on comparison with the cone of friction, which has a similar state decision diagram. Moreover, the behavioral simulation of a concrete model 2-DOF biped robot is used to analyze the sliding features in terms of the asymmetry of the dynamics of both legs.