Computer simulation of controlled motion of dual fingers with soft tips grasping and manipulating an object
Computer simulation of controlled motion of dual fingers with soft tips grasping and manipulating an object
复制标题
计算机模拟软尖双指抓取和操纵物体的受控运动
DOI：
10.1163/156855302760064192
复制
发表时间：
2002
影响因子：
2
通讯作者：
S. Arimoto
中科院分区：
文献类型：
--
作者：
P. Nguyen;S. Arimoto
在以前的文件中，一组双多关节手指与软，可变形的提示掌握和操纵一个刚性的物体的动态制定了一个系统的非线性微分方程的欧拉-拉格朗日的形式主义。虽然已经指出了紧密区域接触的几何约束，但为了避免在控制律设计和动力学稳定性分析中增加复杂性，在系统的运动方程中故意忽略了它们。在无源性的基础上，探讨了双软尖手指稳定抓取物体并调节物体姿态的感觉反馈控制方案，通过理论分析证明了被控变量的渐近收敛性，但没有给出仿真结果。在本文中，首先，我们进行了数值模拟的基础上彻底的动力学的整体系统，其次，发现软指尖和对象之间的紧密区域接触所产生的约束力的重要作用。本文表明，这些约束的无知不产生任何忠实的运动系统，即使在近似意义上，虽然这些条款不引起任何工作，是无关的被动。事实上，在仿真中，它会导致状态变量的不稳定性增加，应该得出结论，它们在动态中不能被忽略。第三，物体-手指系统在紧密面接触几何约束下的运动可以用一组混合的非线性微分方程和代数方程表示。然后，整个系统的动力学仿真，其中的约束条件考虑到开发使用的思想的约束稳定化方法。计算机仿真结果证实了所提出的控制律的有效性。特别是，它被验证的约束力出现在切向的物体表面的方向收敛到零，快速实现稳定的抓持。最后，一个模拟运动的棒图，以说明一个过程中的把握和操纵一个刚性物体的软手指。
In the previous paper, the dynamics of a set of dual multi-joint fingers with soft, deformable tips grasping and manipulating a rigid object were formulated by a system of nonlinear differential equations of Euler-Lagrange's formalism. Although geometric constraints of tight area contacts have been pointed out, they were neglected purposely in motion equations of the system in order to avoid increasing complication arising in design of control laws and in the analysis of the stability of the dynamics. On the basis of passivity, sensory feedback control schemes for stably grasping an object by a set of dual soft-tip fingers and regulating the object's posture have been explored and a proof for asymptotic convergences of controlled variables has been presented by theoretical analysis without showing any simulation result. In this paper, first, we carry out a numerical simulation based on the thorough dynamics of the overall system and, secondly, find the important role of constraint forces arising from tight area contacts between soft finger-tips and the object. The paper shows that ignorance of these constraints does not yield any faithful motion of the system even in an approximate sense, although the terms do not induce any work and are irrelevant to the passivity. In fact, in simulation, it causes increased instabilities of state variables and it should be concluded that they cannot be neglected in the dynamics. Thirdly, motions of the object–fingers system under geometric constraints of tight area contacts have been expressed by a set of mixed nonlinear differential and algebraic equations. Then, the overall system dynamics for simulation in which the constraint conditions are taken into account are developed by using the idea of a constraints stabilization method. Computer simulation results have confirmed the effectiveness of the proposed control laws. In particular, it is verified that the constraint forces appearing in the directions tangential to the object surfaces converge to zero quickly as stable grasping is realized. Finally, a stick graph of simulated motion is presented to illustrate a process of grasping and manipulating a rigid object by soft fingers.