AI 中文总结
本文提出集成前馈框架，结合滞后补偿、基于EM图像的POI测量与换向角域迭代学习控制，解决电子显微镜载物台缺少专用POI传感器等问题，使POI跟踪误差显著降低。
AI 中文摘要
电子显微镜需要在长行程上实现纳米级的样品定位，压电步进执行器非常适合该任务，但其精度受滞后、机械对准误差及非共置传感的限制。已有研究在简化的实验室装置上解决了这些限制，但将其扩展到完整的电子显微镜载物台时，会出现耦合非线性运动学，且关键在于缺少专用的感兴趣点（POI）传感器。本文提出一种集成前馈框架，用于在运行中的电子显微镜内部的该类载物台上实现精密定位：首先对每个元件进行滞后补偿，使执行器响应线性化；由于缺少专用POI传感器，通过基于互相关的图像跟踪从电子显微镜（EM）图像中构建POI测量值，再基于该测量值构建编码器代理以表征POI位置；随后采用换向角域迭代学习控制，将该代理作为误差信号，以抵消步进的可重复扰动；由于学习到的校正项以换向角参数化，因此可在驱动频率的准静态范围内传递。该框架使实验室装置上的POI跟踪误差降低超过13倍，在运行中的透射电子显微镜上降低7至12倍。
英文摘要
Electron microscopy requires nanometer-scale specimen positioning over a long stroke. Piezo-stepper actuators are well suited for this task, but their accuracy is limited by hysteresis, mechanical misalignments, and non-collocated sensing. Prior work has addressed these limitations on simplified lab setups. However, extending to a full electron microscope stage introduces coupled nonlinear kinematics and, importantly, the absence of a dedicated point-of-interest (POI) sensor. This paper presents an integrated feedforward framework for precision positioning on such a stage inside an operational electron microscope. Per-element hysteresis compensation first linearizes the actuator response. In the absence of a dedicated POI sensor, a POI measurement is constructed from EM images through cross-correlation-based image tracking. From this measurement, we construct an encoder-based proxy for the POI position. Commutation-angle-domain iterative learning control then uses this proxy as its error signal to cancel the repeatable disturbances of stepping. Because the learned corrections are parameterized in the commutation angle, they transfer across the quasi-static range of drive frequencies. The framework reduces the POI tracking error by over 13x on the lab setup and by 7 to 12x on an operational transmission electron microscope.
Comments11 pages, 13 figures. This work has been submitted to the IEEE for possible publication
