Passive Reaction Analysis for Grasp Stability
Passive Reaction Analysis for Grasp Stability
复制标题
抓握稳定性的被动反应分析
DOI：
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发表时间：
2018
影响因子：
5.6
通讯作者：
M. Ciocarlie
中科院分区：
文献类型：
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作者：
Maximilian Haas;G. Iyengar;M. Ciocarlie
本文重点研究了多指机器人抓取过程中的以下问题：假设在抓取物体上施加外部扳手，手与物体之间以及手关节之间的接触力是否会以这种方式响应以保持准静态平衡？特别地，我们假设由电动机主动施加的关节力矩没有变化；接触力和关节扭矩的任何变化都是由于响应外部干扰而产生的被动效应。这种被动影响包括，例如，由高齿轮电机驱动的关节（在实践中很常见），因此对外部扭矩的响应不会反向驱动。为了考虑在这种情况下遇到的非线性现象，以及现有方法没有考虑到的非线性现象，我们将问题表述为迭代求解器内循环中使用的混合整数规划。我们提出的证据表明，该公式捕获了重要的影响，以评估一个抓住的稳定性采用一些最常用的驱动机构。实践者注意：一旦选择了对给定对象的把握，我们的方法就有多种可能的应用。首先，它可以用来确定预载荷的选择（即，在抓取创建时施加到关节的扭矩）如何影响抓取的稳定性。其次，一旦选择了预负载，我们的方法就可以用来确定哪些外部干扰可以通过被动效应来抵抗，而不需要进一步改变发送给电机的命令。我们相信这种方法特别适用于没有配备触觉或本体感觉传感器的大型抓取设备，因此无法感知外部干扰或控制关节扭矩，但由于被动阻力效应仍然有效。
In this paper, we focus on the following problem in multifingered robotic grasping: assuming that an external wrench is being applied to a grasped object, will the contact forces between the hand and the object, as well as the hand joints, respond in such a way to preserve quasi-static equilibrium? In particular, we assume that there is no change in the joint torques being actively exerted by the motors; any change in contact forces and joint torques is due exclusively to passive effects arising in response to the external disturbance. Such passive effects include, for example, joints that are driven by highly geared motors (a common occurrence in practice) and thus do not back drive in response to external torques. To account for nonlinear phenomena encountered in such cases, and which existing methods do not consider, we formulate the problem as a mixed-integer program used in the inner loop of an iterative solver. We present evidence showing that this formulation captures important effects for assessing the stability of a grasp employing some of the most commonly used actuation mechanisms. Note to Practitioners—Once a grasp of a given object has been chosen, our method has multiple possible applications. First, it can be used to determine how the choice of a preload (i.e., the torques applied to the joints as the grasp is created) affects the stability of the grasp. Second, once a preload has been chosen, our method can be used to determine which external disturbances can be resisted solely through passive effects, without further changes to the commands sent to the motors. We believe this approach is particularly relevant for the large family of grasping devices that are not equipped with tactile or proprioceptive sensors, and are thus unable to sense external disturbances or to control joint torques, but are still effective thanks to passive resistance effects.