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.

翻译：大多数腿式机器人采用串联连杆和驱动器构建腿结构，并通过复杂控制器与传感器反馈进行控制。相比之下，动物进化出了多段腿、关节间机械耦合以及多段足部结构，使其能在各类地形上敏捷奔跑——其运动控制的复杂性反而更低。本研究重点开发可在自然地形中抵抗滑移与沉陷的足部机构。我们展示了安装在仿鸟腿机器人上的多段足部初步成果，该机器人采用多关节肌腱机械耦合。实验表明，在多种软硬基底上，我们的单段和两段自适应机械足部在开始滑移前能产生更高的有效水平力。同时观察到，相较于球形足和圆柱形足，分段足部能减少软基底上的沉陷量。研究证实，多段足部可提供更广泛的压力中心有效作用范围，这不仅适用于双足机器人，也适用于在斜坡和自然地形中行走的四足机器人。这些发现还为理解平胸鸟类等动物的分段足部功能提供了理论依据。