This paper presents a fast tight-tolerance threading technique for string and rope. Instead of relying on simulations of these deformable objects to plan a path or compute control actions, we control the movement of the string with a virtual magnetic vector field emanating from the narrow openings we wish to thread through. We compute an approximate Jacobian to move the tip of the string through the vector field and propose a method to promote alignment of the head of the string to the opening. We also propose a method for re-grasping the string based on the relationship between the string's configuration, the orientation of the opening, and direction of gravity. This re-grasping method in conjunction with our controller can be used to thread the string through a sequence of openings. We evaluated our method in simulation (with simulated sensor noise) and on the Da Vinci surgical robot. Our results suggest that our method is quite robust to errors in sensing, and is capable of real-world threading tasks with the da Vinci robot, where the diameter of the string (3.5mm) and opening (4.9mm) differ by only 1.4 mm.
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机译：本文提出了一种用于线绳的快速紧公差穿线技术。我们不用依靠对这些可变形物体的模拟来规划路径或计算控制动作，而是使用虚拟磁场矢量控制弦的运动，该磁场从我们希望穿过的狭窄开口中散发出来。我们计算一个近似的雅可比行列式，以通过矢量场移动弦的尖端，并提出一种方法来促进弦的头部与开口对齐。我们还提出了一种根据弦的形状，开口的方向和重力方向之间的关系重新捕捉弦的方法。结合我们的控制器使用的这种重新抓取方法可用于使字符串穿过一系列开口。我们在模拟（具有模拟传感器噪声）和达芬奇外科手术机器人上评估了我们的方法。我们的结果表明，我们的方法对于感知错误非常鲁棒，并且能够使用da Vinci机器人执行实际的穿线任务，其中，线绳直径（3.5mm）和开口直径（4.9mm）仅相差1.4 mm 。
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