Stability on a manifold: simultaneous realization of grasp and orientation control of an object by a pair of robot fingers
Stability on a manifold: simultaneous realization of grasp and orientation control of an object by a pair of robot fingers
复制标题
流形稳定性：一对机器人手指同时实现物体的抓取和方向控制
DOI：
10.1109/robot.2003.1241942
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
K. Tahara
中科院分区：
文献类型：
--
作者：
S. Arimoto;J. Bae;K. Tahara
本文以拉格朗日方程为基础，研究了具有半球形指端的多自由度机器人手指在滚动接触约束下抓取刚性物体的运动稳定性理论。当一对两个自由度。以手指为例，将整个手指-物体系统的运动限制在一个平面内，结果表明，尽管存在四个代数约束，但为了实现稳定抓取，手指-物体系统的总自由度是冗余的。为了在不引入额外性能指标的情况下解决冗余问题，引入了从高维流形到低维流形的运动稳定性的概念，该流形表示一组具有给定接触力的稳定抓取状态，从而严格地证明了动态意义上的稳定抓取是通过基于手指关节角度和物体旋转角度的测量数据构建的感觉反馈来实现的。在此基础上，进一步证明了存在一个附加的感觉反馈，该反馈不仅实现了对目标的稳定抓取，而且实现了对目标的姿态控制。这些结果可以推广到另外两种情况：1)整个系统的运动被限制在垂直平面上，因此它直接受到重力的影响；以及2)物体具有不平行但平坦的表面。
This paper is concerned with a stability theory of motion governed by Lagrange's equation for a pair of multi-degrees of freedom robot fingers with hemispherical finger ends grasping a rigid object under rolling contact constraints. When a pair of two DOF. fingers is used and motion of the overall fingers-object system is confined to a plane, it is shown that the total degree of freedom of the fingers-object system is redundant for realization of stable grasping though there arise four algebraic constraints. To resolve the redundancy problem without introducing extra performance specifications, a concept of stability of motion starting from a higher dimensional manifold to a lower-dimensional manifold expressing a set of states of stable grasp with prescribed contact force is introduced and thereby it is proved in a rigorous way that stable grasp in a dynamic sense is realized by a sensory feedback constructed on the basis of measurement data of finger joint angles and the rotational angle of the object. Further, it is shown that there exists an additional sensory feedback that realizes not only stable grasp but also orientation control of the object concurrently. These results can be extended to other two cases that: 1) motion of the overall system is confined to a vertical plane and therefore it is affected directly by the gravity; and 2) the object has non-parallel but flat surfaces.