Robustness and adaptivity: advanced control and estimation algorithms for the transverse dynamic atomic force microscope

鲁棒性和适应性：横向动态原子力显微镜的先进控制和估计算法

• 批准号: EP/I034882/1
• 负责人: Guido Herrmann
• 金额: $ 52.39万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FI034882%2F1
• 关键词: Robustness; adaptivity; advanced; control; estimation

Observing the dynamic behaviour and interactions of single biomolecules is a long-standing goal to facilitate bio-medical research. Standard practice is to use one of several scanning probe microscopes (SPMs), principally atomic force microscopy (AFM). The principle of an AFM is simple: a horizontally oriented cantilever with a very sharp tip is moved across the object of interest, allowing the capture of a three dimensional topographical image. However, the low forces and fast timescales of the fundamental inter-molecular events of interest in bio-medical sciences, generally lie far outside the operational range of commercial AFMs, which typically require several minutes per image. Thus, while AFMs can provide sub-molecular resolution of biomolecules under physiological conditions (cf. electron microscopy which uses a vacuum) there are two significant disadvantages of AFMs still to be overcome.- slow imaging rates: A typical 256x256 pixel image takes 60 seconds to produce.- excessive interaction forces during imaging: A significant challenge to imaging biomolecular interactions is that the forces typically present between the probe and the sample disturb or even damage the biomolecules.To counter these issues, we will combine the latest advances in control theory with the novel SPM instrumentation, currently in development in Bristol, to produce a new scanning probe microscope capable of imaging these fragile samples without damaging them: Thus, Bristol's transverse dynamic force microscope (TDFM) will represent a breakthrough in both SPM instrumentation and the study of biomolecules.In Bristol's TDFM, the probe is aligned perpendicularly to the sample surface (rather than parallel to it, as in AFMs) and oscillates in the plane of the sample. The amplitude of oscillation decreases as the tip-sample separation distance decreases. The amplitude of the probe oscillation can be used as a measurement signal to control the probe-sample separation with sub-nanometer precision. When using this control method, at no point during scanning should the probe come into contact with the sample surface.Novel control methods will create a high-speed TDFM (HS-TDFM) by-controlling the fast movement of the cantilever height (z-motion)-controlling the fast placement of any (biological) specimen to be observed (x-y-motion)-estimating sample-cantilever forces, e.g. Van-der Waals forces, to better understand the wealth of measured information for faster and simpler fusion & processing of data obtained from the HS-TDFM.Before any of this is possible, the TDFM will be redesigned to incorporate highly precise sensor technology and to obtain the best possible dynamic behaviour. The modern control approaches will include linear robust control approaches, nonlinear sliding mode control, nonlinear adaptive (neural network) control, modern estimation/observer techniques using sliding modes, and adaptive principles.The challenges will be to-achieve practical control at bandwidths above 1MHz;-understand & exploit the nonlinear HS-TDFM dynamics for better data interpretation;-develop novel estimators/observers combining the paradigms of adaptive and sliding mode methods, for signal and parameter identification;-incorporate novel estimation and control approaches for improving the control system of the HS-TDFM.The resulting HS-TDFM will be a true non-contact imaging technique capable of comparable spatial resolution and lower interaction forces than AFMs. The HS-TDFM will display pico-Newton force-sensitivity and provide a wealth of information from direct observation of the interacting biomolecules. It will collect multiple images per second as required for observing biological processes. This will not only benefit life-sciences but also support SPM users in material science, producers of nano-sized systems, and in nano-electronics, e.g. microprocessors.

观察单个生物分子的动态行为和相互作用是促进生物医学研究的长期目标。标准做法是使用几种扫描探针显微镜（SPMs）之一，主要是原子力显微镜（AFM）。AFM的原理很简单：在感兴趣的物体上移动一个具有非常尖锐尖端的水平取向悬臂，从而可以捕获三维地形图像。然而，生物医学科学中感兴趣的基本分子间事件的低力和快速时间尺度通常远远超出了商用AFMs的操作范围，商用AFMs通常需要几分钟才能获得一张图像。因此，虽然原子力显微镜可以在生理条件下提供生物分子的亚分子分辨率（例如使用真空的电子显微镜），但原子力显微镜仍有两个明显的缺点有待克服。-成像速度慢：一个典型的256x256像素的图像需要60秒才能产生。-成像过程中过度的相互作用力：成像生物分子相互作用的一个重大挑战是，通常存在于探针和样品之间的力会干扰甚至破坏生物分子。为了解决这些问题，我们将把控制理论的最新进展与布里斯托尔目前正在开发的新型SPM仪器相结合，生产一种新的扫描探针显微镜，能够对这些脆弱的样品进行成像而不会损坏它们。因此，布里斯托尔的横向动态力显微镜（TDFM）将代表SPM仪器和生物分子研究的突破。在布里斯托尔的TDFM中，探针垂直于样品表面（而不是像原子力显微镜那样平行于样品表面），并在样品平面上振荡。振荡幅度随着尖端-样品分离距离的减小而减小。探头振荡的振幅可以作为测量信号，控制亚纳米精度的探针-样品分离。当使用这种控制方法时，在扫描过程中探针不应与样品表面接触。新的控制方法将创建高速TDFM (HS-TDFM)，通过控制悬臂高度的快速运动（z运动）-控制任何（生物）标本的快速放置观察（x-y运动）-估计样品-悬臂力，例如范德华力，以更好地理解丰富的测量信息，更快更简单地融合和处理从HS-TDFM获得的数据。在这一切成为可能之前，TDFM将被重新设计，以结合高精度的传感器技术，并获得最佳的动态性能。现代控制方法将包括线性鲁棒控制方法、非线性滑模控制、非线性自适应（神经网络）控制、使用滑模的现代估计/观测器技术和自适应原理。挑战将是在1MHz以上的带宽下实现实际控制；-理解和利用非线性HS-TDFM动态，以更好地解释数据；-结合自适应和滑模方法的范例，开发新的估计器/观测器，用于信号和参数识别；-采用新的估计和控制方法来改进HS-TDFM的控制系统。由此产生的HS-TDFM将是一种真正的非接触成像技术，能够与原子力显微镜相比具有相当的空间分辨率和更低的相互作用力。HS-TDFM将显示出皮牛顿力灵敏度，并提供丰富的信息，直接观察相互作用的生物分子。它将根据观察生物过程的需要每秒收集多张图像。这不仅将使生命科学受益，而且还将支持材料科学、纳米系统生产商和纳米电子学（例如微处理器）领域的SPM用户。

项目成果

Observer design for sampled-data systems with unknown inputs and uncertainties based on quasi sliding motion

基于拟滑动运动的未知输入和不确定性采样数据系统的观测器设计

• DOI: 10.23919/acc.2018.8430759
• 发表时间: 2018
• 作者: Nguyen T

Cantilever dynamics modelling for the Transverse Dynamic Force Microscope

• DOI: 10.1109/cdc.2014.7039564
• 发表时间: 2014-12
• 期刊: 53rd IEEE Conference on Decision and Control
• 作者: Thang Nguyen-Tien;C. Edwards;G. Herrmann;T. Hatano;S. Burgess;M. Miles

Adaptive estimation of the shear force in the cantilever dynamics of the Transverse Dynamic Force Microscope

• DOI: 10.1109/isic.2014.6967602
• 发表时间: 2014-10
• 期刊: 2014 IEEE International Symposium on Intelligent Control (ISIC)
• 作者: Thang Nguyen-Tien;C. Edwards;G. Herrmann;T. Hatano;S. Burgess;M. Miles

A specimen-tracking controller for the transverse dynamic force microscope in non-contact mode

非接触式横向动力显微镜标本跟踪控制器

• DOI: 10.1109/acc.2016.7526838
• 发表时间: 2016
• 作者: Hatano T

Discrete-time Implementation of Adaptive Estimation in the Transverse Dynamic Force Microscope

横向动力显微镜中自适应估计的离散时间实现

• DOI: 10.1109/icstcc55426.2022.9931889
• 发表时间: 2022
• 作者: Nguyen T