Multi-segmented Adaptive Feet for Versatile Legged Locomotion in Natural Terrain

TL;DR

This paper introduces multi-segmented, mechanically adaptive feet for legged robots inspired by animals, demonstrating improved traction and reduced sinking on various terrains, which simplifies control and enhances versatility.

Contribution

It presents novel multi-segmented foot mechanisms with mechanical coupling that improve grip and stability on natural terrains, inspired by animal foot structures.

Findings

Multi-segmented feet increase horizontal force capacity before slipping.

Segmented feet reduce sinking on soft substrates.

Large range of pressure points suitable for diverse terrains.

Abstract

Most legged robots are built with leg structures from serially mounted links and actuators and are controlled through complex controllers and sensor feedback. In comparison, animals developed multi-segment legs, mechanical coupling between joints, and multi-segmented feet. They run agile over all terrains, arguably with simpler locomotion control. Here we focus on developing foot mechanisms that resist slipping and sinking also in natural terrain. We present first results of multi-segment feet mounted to a bird-inspired robot leg with multi-joint mechanical tendon coupling. Our one- and two-segment, mechanically adaptive feet show increased viable horizontal forces on multiple soft and hard substrates before starting to slip. We also observe that segmented feet reduce sinking on soft substrates compared to ball-feet and cylinder-feet. We report how multi-segmented feet provide a large range of viable centre of pressure points well suited for bipedal robots, but also for quadruped robots on slopes and natural terrain. Our results also offer a functional understanding of segmented feet in animals like ratite birds.