Study on an algorithm for grasping an unknown object by robotic hand

当机器人手接近未知物体并稳定地抓住它时，从感测的角度来看，有两个主要考虑因素。一个是检测机器人手与未知物体的接触位置，另一个是检测物体的表面几何形状。接触点为感测表面几何形状提供了良好的起点。通过这项研究基金的主要成果总结如下：1。接触点检测通过柔性关节和位置控制关节的适当组合，连杆系统可以在保持连杆与物体接触的同时改变其连杆姿态。结果表明，通过选择两个不同的姿态变化运动的连杆，我们可以计算一个相交点，导致一个近似的接触点。当链接以相对较高的速度撞击对象时，会出现动态效果，因此，链接系统可能会在碰撞点反弹。它还表明，即使在这种情况下，我们可以获得一个近似的接触点，如果链接再次接触的对象与不同的链接姿态。我们还表明，如果我们可以假设一个指尖触觉传感器，获得一个精确的接触点。2.物体形状感知在新开发的三关节机器人的指尖安装了指尖触觉传感器。提出的传感算法由两部分组成，一部分是使传感器沿着物体的切线方向移动，另一部分是保持传感器的姿态，使传感器的最敏感区域始终与待测物体接触。

When a robotic hand approaches an unknown object and grasps it stably, there are two primary considerations from the viewpoint of sensing. One is to detect contact location between robotic hand and unknown object and the other is to detect the surface geometry of object. The contact point provides a good starting point for sensing the surface geometry. The main results through this research grant are summarized below: 1. Contact point sensing With a proper combination of compliant joint and position-controlled joint, a link system can change its link posture while maintaining contact between the link and an object. It was shown that by selecting two different link posture during posture changing motion, we can compute an intersecting point which leads to an approximate contact point. When a link hits an object with relatively high speed, dynamic effects appears and as a result, the link system may bounce at the point of collision. It was also shown that even under such a case, we can obtain an approximate contact point if the link again contacts with the object with a different link posture. We also showed that an exact contact point is obtained if we can assume a finger-tip tactile sensor. 2. Object shape sensing A finger-tip tactile sensor was mounted at the tip of the newly developed three-jointed robot. The proposed sensing algorithm is composed of two parts, namely, one is to move the sensor along the tangential direction of object, and the other is to maintain the sensor attitude so that the most sensitive area of the sensor can always contact with the object to be detected.