Generation of Stealth Walking Gait on Frictionless Descending Stairs Utilizing Upper Body and Reaction Wheel

Abstract

Towards adaptation to slippery ground surface for underactuated locomotion robots, the authors proposed the method of stealth walking, which avoids energy loss at landing of swing foot. Moreover, they proposed angular momentum constraint control (AMCC), which constraints the horizontal ground reaction force to zero, to make the robots walk on the frictionless road surface stably. In this paper, we investigate a more severe situation, i.e., stable walking on frictionless descending stairs. First, we introduce a mathematical model of an underactuated rimless wheel with an upper body and a reaction wheel for analysis, and develop the control law for achieving trajectory tracking control of the stance-leg angle and AMCC simultaneously. Second, we investigate the validity of the proposed method and discuss the nonlinearity of zero dynamics through numerical simulations.