Supporting leg sliding analysis of a 5-DOF biped robot under friction force

When dealing with biped robots it is common to consider some specific assumptions in order to evaluate particular control strategies. One of these referred assumptions implies that the contact point with the walking surface does not move along the walking axis. Although, in some practical situations, this movement could be neglected, this fact mainly depends on the friction characteristics between the contact points. This work is focused on the slip dynamic analysis of the supporting contact point of a biped robot along the walking surface. Analytical expressions to determine conditions of the slip phenomenon are developed by considering an additional degree of freedom at the end of the supporting leg.