Underactuated rimless wheel with small passive rollers aiming at verification experiment for sliding limit cycle walking

This paper proposes a novel underactuated rimless wheel (URW) that has high stiffness and reproduces walking motion sliding on a slippery road surface. First, we describe the overview of the experimental URW we developed and its mechanical features. Second, we develop the equations of motion and collision for the ideal URW with small passive rollers, and discuss the collision dynamics for stance-leg exchange with the prospect of transition to non-instantaneous double-support motion. Third, we perform numerical simulations to understand the fundamental properties of the gait rolling on a rigid road surface and its similarity to limit cycle walking on a slippery road surface.