Robot Hand based on a Spherical Parallel Mechanism for Within-Hand Rotations about a Fixed Point
Robot Hand based on a Spherical Parallel Mechanism for Within-Hand Rotations about a Fixed Point
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DOI：
10.1109/iros51168.2021.9636704
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发表时间：
2021-09
期刊：
影响因子：
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通讯作者：
Vatsal V. Patel;A. Dollar
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文献类型：
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作者：
Vatsal V. Patel;A. Dollar
在三个空间轴上旋转被抓取的物体是具有挑战性的，因为运动学冗余的机械手需要复杂的手内旋转控制方案，而简单的平行抓取器需要低效的整个手臂运动。我们提出了一种新颖的三指机器人手设计，其灵感来自于球面并联机构，仅用3个致动器即可实现这些旋转。该手被设计为在每一个手-物体构型中，物体姿态沿着一个有固定中心的球体运动，该球体由手指转动轴的交点决定，与物体形状、姿态和初始抓握构型无关。基于3-RRS球面机械臂对机械手进行优化，使其旋转工作空间尺寸和操作运动质量达到最大。从这些参数出发，我们通过抓取测试、操作表征和现实任务场景来实现和实验评估手设计，结果表明手能够抓取各种物体几何形状，并能够围绕固定点完成精确的单自由度和多自由度旋转。我们相信这种设计可以显著提高鲁棒性，简化手内灵巧旋转的控制，这在增强低自由度机器人手臂的能力方面具有实用价值，而无需活动手腕。
Rotating a grasped object about all three spatial axes is challenging, because kinematically redundant robot hands require complex control schemes for within-hand rotations, and simple parallel grippers require inefficient whole arm motions. We present a novel 3-finger robot hand design inspired by a spherical parallel mechanism that achieves these rotations with just 3 actuators. The hand is designed such that at every hand-object configuration, the object pose moves along a sphere with a fixed center, which is determined by the intersection of the fingers’ revolute axes and is independent of the object shape, pose, and the initial grasp configuration. We optimize the hand based on 3-RRS spherical manipulator to maximize both its rotational workspace size and manipulation motion quality. From these parameters, we implement and experimentally evaluate the hand design through grasping tests, manipulation characterization, and real-world task scenarios, which show that the hand is able to grasp a variety of object geometries and accomplish precise single and multi-DOF rotations about a fixed point. We believe this design can remarkably improve robustness and simplify control for dexterous within-hand rotations, which finds utility in augmenting the capabilities of low-DOF robot arms without an active wrist.