Bioinspired hooves for robotics: structural, material, and functional insights.

Hoofed animals such as mountain goats, camels, horses, cows, and pigs exhibit exceptional capability in managing complex contact dynamics within their ecological niches, ranging from steep rocky slopes to loose sand and muddy ground. Recent numerical modelling and experimental work have demonstrated that the passive dynamics of mountain goat hooves can significantly reduce slippage without the need for active closed-loop control, provided that joint compliance lies within an appropriate range. In this paper, we review the biomechanics of biological hooves in relation to their environmental specialisations and examine the corresponding design principles, advantages, and limitations of robotic feet. By integrating evidence from biological morphology, robotic prototypes, and contact mechanics, we identify the critical morphological and material features required for robotic feet to perform effectively across diverse terrains. The paper highlights that: (a) layered and anisotropic material organisation in biological hooves enables passive, terrain-adaptive contact dynamics that provide stability and traction without active control; (b) anticipatory and morphology-driven contact modulation can replace high-bandwidth control in legged robots. This involves tunability of mechanical parameters, such as stiffness, damping, and contact geometry; (c) future robotic feet should combine bio-informed minimalism with adaptive compliance to achieve terrain-general locomotion.