Department of Mechanics and School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China.
Department of Aircraft Control, School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China.
Soft Robot. 2023 Feb;10(1):77-87. doi: 10.1089/soro.2021.0147. Epub 2022 Apr 21.
Actuators for fast capture are essential in the tasks of space structure assembly and space debris disposal. To avoid damage and rebound caused by collision, the mechanical devices for capture or docking impose very strict restrictions on the collision speed. The gripper made of soft material can realize compliant grasping, but its actuating speed and driving mode should adapt to the scenarios of grasping moving objects in space. By harnessing the rapid occurrence of structural instability and tuning its triggering conditions, we present a soft and bistable gripper for dynamic capture. The gripper deforms on the collision with other objects, and it absorbs the kinetic energy of the objects to trigger an instability, and then achieve fast grasping as well as cushioning. This process does not need any other input energy, and it greatly simplifies the conventional driving devices so as to realize the miniaturized and light-weight gripping actuation. The proper pre-deformation to the bistable structure of the gripper enables one to dynamically adjust the energy barrier for triggering the onset of instability to achieve the optimal grasping and buffering effect according to the kinetic characteristics of targets. After finishing one grasping task, the bistable gripper can automatically return to its initial state and release the target via a self-designed cable-driven mechanism. The ground-testing experiment demonstrates that the proposed soft gripper is capable to grasp, transfer, and release moving targets, and it thus possesses great potential to fulfill challenging operations in space missions.
在空间结构装配和空间碎片处理等任务中，快速捕获的致动器是必不可少的。为了避免因碰撞而造成的损坏和反弹，用于捕获或对接的机械装置对碰撞速度施加了非常严格的限制。由软材料制成的夹具可以实现柔顺抓取，但它的驱动速度和驱动方式应适应在太空中抓取移动物体的场景。通过利用结构失稳的快速发生并调整其触发条件，我们提出了一种用于动态捕获的软双稳态夹具。夹具在与其他物体碰撞时会发生变形，并吸收物体的动能来触发不稳定性，从而实现快速抓取和缓冲。这个过程不需要任何其他输入能量，大大简化了传统的驱动装置，从而实现了小型化和轻量化的夹持驱动。适当的预变形可以动态调整双稳态结构的能量势垒，以根据目标的动力学特性实现最佳的抓取和缓冲效果。完成一个抓取任务后，双稳态夹具可以通过自行设计的缆绳驱动机构自动返回到初始状态并释放目标。地面测试实验表明，所提出的软夹具能够抓取、传递和释放移动目标，因此具有在空间任务中完成挑战性操作的巨大潜力。
