Control of a powered planar biped without ankle actuation

This paper introduces a control method for a powered planar biped without ankle actuation. The existence of an ideal slope, on which the biped can walk without actuation, is assumed. The proposed controller can realize stable walking, as if the biped were on an ideal slope when the biped is on a different slope. The proposed controller has no singular points, whereas the control input diverges to infinity, unlike conventional controllers for powered passive walkers. Selected simulations were executed with a simple compass-like biped and a four-link biped with a mass body to validate the effectiveness of the proposed controller.