The continuous monitoring by drone swarms remains a challenging problem due to the lack of power supply and the inability of drones to land on uneven surfaces. Heterogeneous swarms, including ground and aerial vehicles, can support longer inspections and carry a higher number of sensors on board. However, their capabilities are limited by the mobility of wheeled and legged robots in a cluttered environment. In this paper, we propose a novel concept for autonomous inspection that we call SwarmGear. SwarmGear utilizes a heterogeneous swarm that investigates the environment in a leader-follower formation. The leader drone is able to land on rough terrain and traverse it by four compliant robotic legs, possessing both the functionalities of an aerial and mobile robot. To preserve the formation of the swarm during its motion, virtual impedance links were developed between the leader and the follower drones. We evaluated experimentally the accuracy of the hybrid leader drone's ground locomotion. By changing the step parameters, the optimal step configuration was found. Two types of gaits were evaluated. The experiments revealed low crosstrack error (mean of 2 cm and max of 4.8 cm) and the ability of the leader drone to move with a 190 mm step length and a 3 degree standard yaw deviation. Four types of drone formations were considered. The best formation was used for experiments with SwarmGear, and it showed low overall crosstrack error for the swarm (mean 7.9 cm for the type 1 gait and 5.1 cm for the type 2 gait). The proposed system can potentially improve the performance of autonomous swarms in cluttered and unstructured environments by allowing all agents of the swarm to switch between aerial and ground formations to overcome various obstacles and perform missions over a large area.

翻译：无人机集群的持续监控仍是一个挑战性难题，原因在于缺乏电源供给且无人机无法在不平整地面上着陆。包含地面与空中飞行器的异构集群可支持更长时间的巡检任务，并搭载更多传感器设备。然而，轮式与腿式机器人在杂乱环境中的机动性限制了其能力。本文提出一种名为SwarmGear的自主巡检新概念。SwarmGear采用异构集群以领航-跟随编队模式探测环境。领航无人机能够降落在崎岖地形上，并通过四条柔性机械腿实现地面移动，兼具空中与移动机器人的双重功能。为保持集群运动过程中的编队形态，我们在领航无人机与跟随无人机之间构建了虚拟阻抗连接。通过实验评估了混合领航无人机的陆面移动精度，发现通过改变步态参数可确定最优步态配置，并测试了两种步态类型。实验显示低横向轨迹误差（平均值2 cm，最大值4.8 cm），且领航无人机能以190 mm步长和3度标准偏航偏差行进。研究考虑了四种无人机编队形态，采用最优编队进行SwarmGear实验时，集群整体横向轨迹误差较低（类型1步态平均值7.9 cm，类型2步态平均值5.1 cm）。本系统通过允许集群所有智能体在空-地编队间切换，可克服各类障碍并执行大范围任务，有望提升自主集群在杂乱与非结构化环境中的性能。