Grasping using an aerial robot can have many applications ranging from infrastructure inspection and maintenance to precise agriculture. However, aerial grasping is a challenging problem since the robot has to maintain an accurate position and orientation relative to the grasping object, while negotiating various forms of uncertainties (e.g., contact force from the object). To address such challenges, in this paper, we integrate a novel passive gripper design and advanced adaptive control methods to enable robust aerial grasping. The gripper is enabled by a pre-stressed band with two stable states (a flat shape and a curled shape). In this case, it can automatically initiate the grasping process upon contact with an object. The gripper also features a cable-driven system by a single DC motor to open the gripper without using cumbersome pneumatics. Since the gripper is passively triggered and initially has a straight shape, it can function without precisely aligning the gripper with the object (within an $80$ mm tolerance). Our adaptive control scheme eliminates the need for any a priori knowledge (nominal or upper bounds) of uncertainties. The closed-loop stability of the system is analyzed via Lyapunov-based method. Combining the gripper and the adaptive control, we conduct comparative real-time experimental results to demonstrate the effectiveness of the proposed integrated system for grasping. Our integrated approach can pave the way to enhance aerial grasping for different applications.

翻译：利用空中机器人进行抓取可应用于诸多领域，从基础设施巡检维护到精准农业。然而，空中抓取是一个颇具挑战性的问题，因为机器人需要保持相对于抓取目标的精确位置和姿态，同时应对各种形式的不确定性（例如来自物体的接触力）。为应对这些挑战，本文集成了一种新型被动抓取器设计与先进自适应控制方法，以实现鲁棒的空中抓取。该抓取器采用具有两种稳定状态（平坦形态与卷曲形态）的预紧力带实现。在此情况下，它能够在接触物体时自动发起抓取过程。该抓取器还配备由单个直流电机驱动的缆绳系统，无需使用笨重的气动装置即可打开抓取器。由于抓取器采用被动触发且初始为直线形态，因此可在不对抓取器与物体进行精确对齐的情况下工作（允许$80$毫米容差）。我们的自适应控制方案无需任何关于不确定性的先验知识（标称值或上界）。通过基于李雅普诺夫的方法分析了系统的闭环稳定性。结合抓取器与自适应控制，我们进行了对比实时实验，验证了所提出的集成系统在抓取方面的有效性。我们的集成方法可为提升不同应用场景下的空中抓取性能铺平道路。