An Iterative-Based Feedforward-Feedback Control Approach to High-Speed Atomic Force Microscope Imaging
An Iterative-Based Feedforward-Feedback Control Approach to High-Speed Atomic Force Microscope Imaging
复制标题
高速原子力显微镜成像的基于迭代的前馈反馈控制方法
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Q. Zou
中科院分区：
文献类型：
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作者：
Ying Wu;Q. Zou
提出了一种基于迭代的前馈-反馈控制方法来实现原子力显微镜（AFM）的高速成像。AFM成像需要在所有x-y-z轴方向上相对于样品精确定位探针。特别地，本文重点关注垂直z轴定位。最近，电流周期反馈迭代学习控制（CCF-ILC）方法已被开发用于精确跟踪给定的期望轨迹（即使当期望轨迹是未知的），它可以被应用于实现一个扫描线上的样品轮廓的精确跟踪。在这篇文章中，我们扩展了这种CCF-ILC方法，整个样本区域的成像。这篇文章的主要贡献是收敛性分析和使用的CCF-ILC方法的输出跟踪在迭代之间的期望的轨迹变化的存在下，相邻扫描线之间的样本地形变化。对于任意两个连续迭代之间出现期望轨迹变化的一般情况，讨论了CCF-ILC系统的收敛性（稳定性），并量化了期望轨迹变化的允许大小。通过比较使用CCF-ILC技术单独使用反馈控制的跟踪误差，讨论了通过使用CCF-ILC方法实现的性能改善。所提出的CCF-ILC控制方法的有效性说明了通过实施它的Z轴控制在AFM成像。实验结果表明，AFM成像速度可以大大提高。
This article presents an iterative-based feedforward-feedback control approach to achieve high-speed atomic force microscope (AFM) imaging. AFM-imaging requires precision positioning of the probe relative to the sample in all x-y-z axes directions. Particularly, this article is focused on the vertical z-axis positioning. Recently, a current-cycle-feedback iterative-learning-control (CCF-ILC) approach has been developed for precision tracking of a given desired trajectory (even when the desired trajectory is unknown), which can be applied to achieve precision tracking of sample profile on one scanline. In this article, we extend this CCF-ILC approach to imaging of entire sample area. The main contribution of this article is the convergence analysis and the use of the CCF-ILC approach for output tracking in the presence of desired trajectory varation between iterations—the sample topography variations between adjacent scanlines. For general case where the desired trajectory variation occurs between any two successive iterations, the convergence (stability) of the CCF-ILC system is addressed and the allowable size of desired trajectory variation is quantified. The performance improvement achieved by using the CCF-ILC approach is discussed by comparing the tracking error of using the CCF-ILC technique to that of using feedback control alone. The efficacy of the proposed CCF-ILC control approach is illustrated by implementing it to the z-axis control during AFM-imaging. Experimental results are presented to show that the AFM-imaging speed can be substantially increased.