Control of contact forces: The role of tactile feedback for contact localization
Control of contact forces: The role of tactile feedback for contact localization
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接触力的控制：触觉反馈在接触定位中的作用
DOI：
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发表时间：
2012
期刊：
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通讯作者：
L. Natale
中科院分区：
文献类型：
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作者：
A. Prete;F. Nori;G. Metta;L. Natale
本文研究了接触点精确估计在力控制中的作用。这项分析的动机是机器人自愿或无意地与身体的不同部位进行接触。通常在没有触觉系统的机器人中实施的控制范例假设接触仅发生在末端执行器处。在本文中，我们试图研究当这个假设没有得到验证时会发生什么。首先我们考虑一个简单的前馈力控制律，然后通过引入比例反馈项来扩展它。对于这两个控制器，我们发现所产生的接触力存在误差，这是由接触点估计中的假设误差引起的。我们表明，根据接触的几何形状，接触点的错误估计可能会引起不期望的关节加速度。我们通过模拟机器人手臂上的测试验证了所提出的分析。此外，我们考虑一个复杂的现实世界场景，其中我们在分析推导中所做的大多数假设都不成立。通过对 iCub 人形机器人的测试，我们看到接触定位错误如何影响并行力/位置控制器的性能。为了估计 iCub 前臂上的接触点和接触力，我们不使用任何环境模型，但我们利用其 6 轴力/扭矩传感器及其传感皮肤。
This paper investigates the role of precise estimation of contact points in force control. This analysis is motivated by scenarios in which robots make contacts, either voluntarily or accidentally, with different parts of their body. Control paradigms that are usually implemented in robots with no tactile system, make the hypothesis that contacts occur at the end-effectors only. In this paper we try to investigate what happens when this assumption is not verified. First we consider a simple feedforward force control law, and then we extend it by introducing a proportional feedback term. For both controllers we find the error in the resulting contact force, that is induced by a hypothetic error in the estimation of the contact point. We show that, depending on the geometry of the contact, incorrect estimation of contact points can induce undesired joint accelerations. We validate the presented analysis with tests on a simulated robot arm. Moreover we consider a complex real world scenario, where most of the assumptions that we make in our analytical derivation do not hold. Through tests on the iCub humanoid robot we see how errors in contact localization affect the performance of a parallel force/position controller. In order to estimate contact points and contact forces on the forearm of the iCub we do not use any model of the environment, but we exploit its 6-axis force/torque sensor and its sensorized skin.