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）极少能实现超过两种模态（即飞行与步行或飞行与栖息）。然而，若能同时具备飞行、栖息与步行能力，通过扩展其工作包线可进一步提升实用性。例如，空中机器人可远距离飞行，在高处栖息以监测周围环境，随后步行穿越可能阻碍飞行的障碍物。鸟类具备这三种能力，为开发同类机器人提供了实用范例。本文提出一种专用仿生禽爪设计，使无人机实现被动栖息或步行。其核心创新在于将霍伯曼连杆腿与鳍射线爪相结合：利用无人机自身重量使爪缠绕栖息点，或反向超伸展形成上弯轮廓以实现稳定地面运动。由于该设计利用了车辆自重，这种欠驱动结构兼具轻量化和低功耗特性。配备钩爪后，45克的爪体可支撑700克无人机以近20度倾角悬挂于栖息点。在杂乱环境阻碍飞行且需长时间任务时，这种飞行、栖息与步行的组合能力至关重要。