Control of underactuated rimless wheel that walks on steep slope

Toward stable gait generation on a steep slope, this paper discusses a method for generating a stable walking gait completing in one step for an underactuated rimless wheel. First, we introduce a model of a six-legged rimless wheel with a reaction wheel, and develop two controllers for the single-limb and double-limb support phases. For easily achieving precise control of the state variables, we apply a discrete-time output deadbeat control for each phase. We numerically analyze the fundamental properties of the generated gait, and show that the target period of the double-limb support phase must be chosen as a significantly long so that the rear and fore feet are grounded during control of the reaction wheel. The gait efficiency is also analyzed in terms of the walking speed and specific resistance through numerical simulations.