Multimodal UAVs (Unmanned Aerial Vehicles) are rarely capable of more than two modalities, i.e., flying and walking or flying and perching. However, being able to fly, perch, and walk could further improve their usefulness by expanding their operating envelope. For instance, an aerial robot could fly a long distance, perch in a high place to survey the surroundings, then walk to avoid obstacles that could potentially inhibit flight. Birds are capable of these three tasks, and so offer a practical example of how a robot might be developed to do the same. In this paper, we present a specialized avian-inspired claw design to enable UAVs to perch passively or walk. The key innovation is the combination of a Hoberman linkage leg with Fin Ray claw that uses the weight of the UAV to wrap the claw around a perch, or hyperextend it in the opposite direction to form a curved-up shape for stable terrestrial locomotion. Because the design uses the weight of the vehicle, the underactuated design is lightweight and low power. With the inclusion of talons, the 45g claws are capable of holding a 700g UAV to an almost 20-degree angle on a perch. In scenarios where cluttered environments impede flight and long mission times are required, such a combination of flying, perching, and walking is critical.

翻译：多模态无人机（UAV）很少具备超过两种模态的能力，即飞行与行走或飞行与栖息相结合。然而，若能同时实现飞行、栖息与行走三种模态，可通过扩展其工作范围进一步提升实用性。例如，空中机器人可长途飞行至高处栖息以俯视环境，随后通过行走避开可能妨碍飞行的障碍物。鸟类具备完成这三项任务的能力，为开发同类机器人提供了实践范例。本文提出一种专用仿生鸟爪设计，使无人机能被动栖息或行走。关键创新在于结合霍伯曼连杆腿结构与鳍射线爪——利用无人机自身重量使爪包裹栖息点，或反向过度伸展形成弧形上翘结构以稳定地面移动。由于利用机体自重，该欠驱动设计兼具轻量化和低功耗特性。配备爪钩后，45克的爪子可承载700克无人机在倾斜近20度的栖息点上稳定停驻。在复杂环境阻碍飞行且需长航时任务场景下，这种融合飞行、栖息与行走的多模态能力至关重要。