Abstract
In this paper we address the control problem of aerial cable suspended load transportation, using multiple Unmanned Aerial Vehicles (UAVs). First, the dynamical model of the coupled system is obtained using the Newton-Euler formalism, for "n" UAVs transporting a load, where the cables are supposed to be rigid and mass-less. The control problem is stated as a trajectory tracking directly on the load. To do so, a hierarchical control scheme is proposed based on the attractive ellipsoid method, where a virtual controller is calculated for tracking the position of the load, with this, the desired position for each vehicle along with their desired cable tensions are estimated, and used to compute the virtual controller for the position of each vehicle. This results in an underdetermined system, where an infinite number of drones' configurations comply with the desired load position, thus additional constrains can be imposed to obtain an unique solution. Furthermore, this information is used to compute the attitude reference for the vehicles, which are feed to a quaternion based attitude control. The stability analysis, using an energy-like function, demonstrated the practical stability of the system, it is that all the error signals are attracted and contained in an invariant set. Hence, the proposed scheme assures that, given well posed initial conditions, the closed-loop system guarantees the trajectory tracking of the desired position on the load with bounded errors. The proposed control strategy was evaluated in numerical simulations for three agents following a smooth desired trajectory on the load, showing good performance.
Abstract (translated)
在本文中,我们解决了使用多个无人飞行器(UAVs)进行的空中电缆悬停负载运输的控制问题。首先,我们使用牛顿-欧拉形式来描述两个耦合系统的动态模型,以“n” UAV运输负载为例,其中电缆应该是 rigid 且无质量。控制问题被表述为直接跟踪负载的轨道跟踪。为此,我们提出了基于吸引力 ellipsoid 方法的分层控制方案,该方案用于计算跟踪负载位置的虚拟控制器,并使用这些信息计算每个车辆的预定位置和期望电缆张力,用于计算每个车辆的虚拟控制器。这导致具有 under determined 性质的系统,因为无限多个无人机的配置符合预定的负载位置,因此可以添加约束来得到唯一的解决方案。此外,这些信息用于计算车辆的姿态参考,并将其发送给基于quaternion 的姿态控制。稳定性分析使用能量函数演示了系统的实际稳定性,即所有误差信号都会被吸引并包含在不变的集合中。因此,提出的方案保证了,给定合适的初始条件,闭环系统可以保证在限制误差的情况下跟踪负载的预定位置。在模拟中,我们对三个代理沿着平滑的负载目标轨迹进行了评估,表现出良好的性能。
URL
https://arxiv.org/abs/2301.11350
