Human-robot interaction will play an essential role in various industries and daily tasks, enabling robots to effectively collaborate with humans and reduce their physical workload. Most of the existing approaches for physical human-robot interaction focus on collaboration between a human and a single ground or aerial robot. In recent years, very little progress has been made in this research area when considering multiple aerial robots, which offer increased versatility and mobility. This paper proposes a novel approach for physical human-robot collaborative transportation and manipulation of a cable-suspended payload with multiple aerial robots. The proposed method enables smooth and intuitive interaction between the transported objects and a human worker. In the same time, we consider distance constraints during the operations by exploiting the internal redundancy of the multi-robot transportation system. The key elements of our approach are (a) a collaborative payload external wrench estimator that does not rely on any force sensor; (b) a 6D admittance controller for human-aerial-robot collaborative transportation and manipulation; (c) a human-aware force distribution that exploits the internal system redundancy to guarantee the execution of additional tasks such inter-human-robot separation without affecting the payload trajectory tracking or quality of interaction. We validate the approach through extensive simulation and real-world experiments. These include scenarios where the robot team assists the human in transporting and manipulating a load, or where the human helps the robot team navigate the environment. We experimentally demonstrate for the first time, to the best of our knowledge, that our approach enables a quadrotor team to physically collaborate with a human in manipulating a payload in all 6 DoF in collaborative human-robot transportation and manipulation tasks.

翻译：人机交互将在各行业和日常任务中发挥关键作用，使机器人能够与人类有效协作并减轻其体力负荷。现有的物理人机交互方法大多集中于人类与单个地面或空中机器人的协作。近年来，在考虑多无人机系统（其具备更强的多功能性和机动性）的研究方向上进展甚微。本文提出了一种新颖的方法，利用多无人机系统实现电缆悬挂负载的物理人机协同运输与操作。所提方法能使被运输物体与人类工作者之间实现流畅直观的交互。同时，我们通过利用多机器人运输系统的内部冗余度，在操作过程中考虑了距离约束。我们方法的核心要素包括：(a) 一种不依赖任何力传感器的协同负载外部力矩估计器；(b) 用于人-无人机协同运输与操作的六维导纳控制器；(c) 一种人类感知的力分配策略，该策略利用系统内部冗余度来保证在不影响负载轨迹跟踪或交互质量的前提下，执行额外任务（如保持人机间距）。我们通过大量仿真和真实世界实验验证了该方法。实验场景包括机器人团队协助人类运输和操作负载，以及人类帮助机器人团队在环境中导航。据我们所知，我们首次通过实验证明，我们的方法能使四旋翼无人机团队在协作人机运输与操作任务中，与人类在全部六个自由度上实现负载操作的物理协作。