Perching allows unmanned aerial vehicles (UAVs) to reduce energy consumption, remain anchored for surface sampling operations, or stably survey their surroundings. Previous efforts for perching on vertical surfaces have predominantly focused on lightweight mechanical design solutions with relatively scant system-level integration. Furthermore, perching strategies for vertical surfaces commonly require high-speed, aggressive landing operations that are dangerous for a surveyor drone with sensitive electronics onboard. This work presents the preliminary investigation of a perching approach suitable for larger drones that both gently perches on vertical tree trunks and reacts and recovers from perch failures. The system in this work, called SLAP, consists of vision-based perch site detector, an IMU (inertial-measurement-unit)-based perch failure detector, an attitude controller for soft perching, an optical close-range detection system, and a fast active elastic gripper with microspines made from commercially-available slapbands. We validated this approach on a modified 1.2 kg commercial quadrotor with component and system analysis. Initial human-in-the-loop autonomous indoor flight experiments achieved a 75% perch success rate on a real oak tree segment across 20 flights, and 100% perch failure recovery across 2 flights with induced failures.

翻译：栖息能力使无人机能够降低能耗、保持锚定以进行表面采样操作，或稳定地监测周围环境。以往针对垂直表面栖息的研究主要集中于轻量化机械设计解决方案，系统级集成相对不足。此外，垂直表面的栖息策略通常需要高速、剧烈的着陆操作，这对搭载精密电子设备的勘测无人机而言存在风险。本研究初步探索了一种适用于较大型无人机的栖息方法，既能轻柔地栖息于垂直树干，又能对栖息故障做出反应并实现恢复。本系统命名为SLAP，包含基于视觉的栖息点检测器、基于IMU（惯性测量单元）的栖息故障检测器、用于软着陆的姿态控制器、光学近距离检测系统，以及采用市售拍腕带制成、配备微型棘刺的快速主动弹性抓取器。我们在改装后的1.2公斤商用四旋翼无人机上通过组件与系统分析验证了该方法的可行性。初步室内人机协同自主飞行实验在真实橡木段上进行20次飞行，实现了75%的栖息成功率；在2次人为诱发故障的飞行中，实现了100%的栖息故障恢复。