Toward Stable and Efficient Gait Inspired by Penguin Walking: Generation of Stable Stepping Motion

This article proposes a method to generate a stable stepping motion for the penguin-inspired link mechanism by swinging the trunk at the waist joint as a preliminary step to generate a gait. In the proposed method, state feedback control for attitude stabilization is introduced to the waist joint, which is the only drive joint, in order to generate stepping motion without falling over even if the trunk is rocked by a simple sinusoidal wave. Specifically, the characteristics of the penguin mechanism are modeled as a simplified two-link mechanism, and a control system is constructed to stabilize the attitude of the penguin robot on an invariant manifold, i.e., equilibrium point, to prevent it from falling over, and the attitude control system is used in combination with trunk swing motion. The validity of the proposed method was evaluated not only for the simplified two-link mechanism, but also for the six-link penguin mechanism by simulation. As a result, it was confirmed that the attitude stabilization control by state feedback works effectively for the penguin mechanism. In addition, it was shown that this method can generate a stable stepping motion by utilizing attitude stabilization control to avoid falling, even under conditions where only a simple sinusoidal drive would cause the robot to fall over.