Gravity based caging describes robotic grasps where the robot hand forms a basket-shape supporting an object against gravity. Basket grasps allow secure object transport with simple hands that use a small number of fingers. A basket grasp can be described in the grasped object configuration space as a cavity formed by the supporting finger c-obstacles and the grasped object gravitational energy. A puncture point exists from which the object c-space trajectory escapes out of the cavity with minimal increase in its gravitational energy, which defines the basket grasp depth. This letter describes an algorithm that computes the depth of basket grasps formed by two-finger robotic hands in 2-D gravitational environments. In the basket depth problem, contact space parametrizes all single and two-finger contacts on the supported object boundary as well as the object orientation on the supporting fingers. Starting from a candidate basket grasp, the algorithm incrementally constructs and searches a basket graph embedded in the low-dimensional contact space. The graph edges represent physical movements of the object in contact with the supporting fingers and the object’s minimal-height escape path on the graph determines the basket grasp security measure. The algorithm is fully implemented and demonstrated on representative examples ranging from simplified to realistic objects.

中文翻译：

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基于双指重力的笼具抓手安全措施的接触空间计算

基于重力的笼子描述了机器人抓取，其中机器人手形成一个篮子形状，支撑物体抵抗重力。篮子抓握允许使用少量手指的简单手安全地运输物体。在被抓物构型空间中，篮子抓握可以描述为由支撑手指c-障碍物和被抓物重力能形成的空腔。存在一个穿刺点，物体 c 空间轨迹从该点逃出空腔，其重力​​能的增加最小，这定义了篮子抓取深度。这封信描述了一种算法，该算法计算二维重力环境中由两指机械手形成的篮子抓取深度。在篮子深度问题中，接触空间参数化支持对象边界上的所有单指和双指接触以及支持手指上的对象方向。从候选篮子抓取开始，该算法逐步构建和搜索嵌入在低维接触空间中的篮子图。图形边缘代表与支撑手指接触的物体的物理运动，图形上物体的最小高度逃生路径决定了篮子抓握安全措施。该算法在从简化对象到现实对象的代表性示例上完全实现和演示。图形边缘代表与支撑手指接触的物体的物理运动，图形上物体的最小高度逃生路径决定了篮子抓握安全措施。该算法在从简化对象到现实对象的代表性示例上完全实现和演示。图形边缘代表与支撑手指接触的物体的物理运动，图形上物体的最小高度逃生路径决定了篮子抓握安全措施。该算法在从简化对象到现实对象的代表性示例上完全实现和演示。