Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
NASA Jet Propulsion Laboratory, Pasadena, CA 91011, USA.
Sci Robot. 2017 Jun 28;2(7). doi: 10.1126/scirobotics.aan4545.
Grasping and manipulating uncooperative objects in space is an emerging challenge for robotic systems. Many traditional robotic grasping techniques used on Earth are infeasible in space. Vacuum grippers require an atmosphere, sticky attachments fail in the harsh environment of space, and handlike opposed grippers are not suited for large, smooth space debris. We present a robotic gripper that can gently grasp, manipulate, and release both flat and curved uncooperative objects as large as a meter in diameter while in microgravity. This is enabled by (i) space-qualified gecko-inspired dry adhesives that are selectively turned on and off by the application of shear forces, (ii) a load-sharing system that scales small patches of these adhesives to large areas, and (iii) a nonlinear passive wrist that is stiff during manipulation yet compliant when overloaded. We also introduce and experimentally verify a model for determining the force and moment limits of such an adhesive system. Tests in microgravity show that robotic grippers based on dry adhesion are a viable option for eliminating space debris in low Earth orbit and for enhancing missions in space.
在太空中抓取和操纵不合作的物体对机器人系统来说是一个新兴的挑战。许多在地球上使用的传统机器人抓取技术在太空中是不可行的。真空夹具需要大气环境，粘性附着物在太空恶劣的环境中失效，而类似手的对向夹具不适合抓取大而光滑的太空碎片。我们提出了一种机器人夹具，它可以在微重力下轻柔地抓取、操纵和释放直径达一米的平坦和弯曲的不合作物体。这得益于 (i) 经过空间认证的受壁虎启发的干式粘合剂，这些粘合剂可以通过施加剪切力选择性地开启和关闭，(ii) 一种负载共享系统，该系统可将这些粘合剂的小块区域扩展到大区域，以及 (iii) 一个非线性无源腕部，在操纵过程中保持刚性，但在过载时具有柔韧性。我们还介绍并实验验证了一种确定这种粘合系统的力和力矩限制的模型。微重力测试表明，基于干式粘附的机器人夹具是消除低地球轨道上太空碎片和增强太空任务的可行选择。
