A Finite-Impulse-Response-Based Approach to Control Acoustic-Caused Probe-Vibration in Atomic Force Microscope Imaging

2017 ◽  
Author(s):  
Sicheng Yi ◽  
Qingze Zou
Keyword(s):  
Atomic Force Microscope ◽  
Impulse Response ◽  
Controller Design ◽  
Finite Impulse Response ◽  
Feedforward Control ◽  
Acoustic Noise ◽  
Noise Cancellation ◽  
Control Approach ◽  
Atomic Force ◽  
Afm Imaging

In this paper, we propose a finite-impulse-response (FIR)-based feedforward control approach to mitigate the acoustic-caused probe vibration during atomic force microscope (AFM) imaging. Compensation for the extraneous probe vibration is needed to avoid the adverse effects of environmental disturbances such as acoustic noise on AFM imaging, nanomechanical characterization, and nanomanipulation. Particularly, residual noise still exists even though conventional passive noise cancellation apparatus has been employed. The proposed technique exploits a data-driven approach to capture both the noise propagation dynamics and the noise cancellation dynamics in the controller design, and is illustrated through the experimental implementation in AFM imaging application.

Data-Driven Post-Filtering of Acoustics Noise in Atomic Force Microscope Imaging

2020 ◽  
Author(s):  
Jiarong Chen ◽  
Qingze Zou
Keyword(s):  
Atomic Force Microscope ◽  
Finite Impulse Response ◽  
Acoustic Noise ◽  
External Noise ◽  
Data Driven ◽  
Residual Noise ◽  
Atomic Force ◽  
Experimental Implementation ◽  
Microscope Imaging ◽  
Filtering Approach

Abstract This paper presents a data-driven dynamics-based filtering approach to eliminate acoustic noise-caused distortion in images of atomic force microscope (AFM). AFM operations are sensitive to external noise as disturbances including acoustic noise as disturbances to the probe-sample interaction directly results in distortions in AFM imaging. Although conventional passive noise cancellation has been employed, limitation exists and residual noise still persists. Advanced online control techniques face difficulty in capturing the complex noise dynamic and limited system bandwidth imposed by the robustness requirement. Therefore, In this work, we propose a finite-impulse-response (FIR) based post-filtering approach to remove the noise-caused distortion in AFM images. Experimental implementation is presented and discussed to illustrate the proposed technique.

An Iterative-Based Feedforward-Feedback Control Approach to High-Speed Atomic Force Microscope Imaging

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Ying Wu ◽  
Qingze Zou
Keyword(s):  
Feedback Control ◽  
Atomic Force Microscope ◽  
High Speed ◽  
Tracking Error ◽  
Control Approach ◽  
Atomic Force ◽  
Afm Imaging ◽  
Current Cycle ◽  
Microscope Imaging ◽  
Precision Tracking

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.

Theoretical Approach to Contrast Mechanism for U-AFM

2002 ◽  
Author(s):  
C. Miyasaka ◽  
B. R. Tittmann ◽  
T. Adachi ◽  
A. Yamaji
Keyword(s):  
Theoretical Analysis ◽  
Resonant Frequency ◽  
Atomic Force Microscope ◽  
Dynamic Theory ◽  
Beam Theory ◽  
Ultrasonic Waves ◽  
Two Dimensional ◽  
Atomic Force ◽  
Afm Imaging ◽  
Contrast Mechanism

When the Ultrasonic-Atomic Force Microscope (U-AFM) is used to form an image of a surface of a specimen having discontinuities, contrast of the specimen in the image is usually stronger than that of an image formed by a conventional Atomic Force Microscope (AFM). In this article, the mechanism of the contrast of the image obtained by the U-AFM was explained by theoretical analysis. A ceramic and metal jointed bar (Steel/Cu/Si3N4) was selected as a specimen for this study. The specimen was located on the surface of a disc transducer generating ultrasonic waves up to 500 KHz, and was vibrated, wherein its first resonant frequency was 133.43 kHz. Both stress and displacement of the specimen were analyzed by classical beam theory and the two-dimensional elasto-dynamic theory. Experimental U-AFM imaging analyses were also carried out to compare the results.

scholarly journals A Correlative Defect Analyzer Combining Glide Test with Atomic Force Microscope

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Jizhong He
Keyword(s):  
High Resolution ◽  
Atomic Force Microscope ◽  
Optical Imaging ◽  
Hard Disk Drive ◽  
Disk Drive ◽  
Atomic Force ◽  
Typical Data ◽  
Afm Imaging ◽  
Afm Analysis

We have developed a novel instrument combining a glide tester with an Atomic Force Microscope (AFM) for hard disk drive (HDD) media defect test and analysis. The sample stays on the same test spindle during both glide test and AFM imaging without losing the relevant coordinates. This enables an in situ evaluation with the high-resolution AFM of the defects detected by the glide test. The ability for the immediate follow-on AFM analysis solves the problem of relocating the defects quickly and accurately in the current workflow. The tool is furnished with other functions such as scribing, optical imaging, and head burnishing. Typical data generated from the tool are shown at the end of the paper. It is further demonstrated that novel experiments can be carried out on the platform by taking advantage of the correlative capabilities of the tool.

Grains Observation Using FIB Anisotropic Etch Followed by AFM Imaging

1996 ◽  
Author(s):  
H. Yamashita ◽  
Y. Hata
Keyword(s):  
Thin Film ◽  
Atomic Force Microscope ◽  
Conventional Technique ◽  
Wet Etching ◽  
Atomic Scale ◽  
Atomic Force ◽  
Afm Imaging ◽  
Al Thin Film ◽  
Anisotropic Etch ◽  
Afm Observation

Abstract It is becoming more important to observe structures and failed sites in LSIs. An atomic force microscope (AFM) can obtain atomic scale topographic images on sample surfaces. To analyze failures in LSIs, several treatments for the AFM observation, such as wet etching and mechanical polishing for a crosssectional imaging, have been proposed so far. A good correlation of AFM images using FIB anisotropic etch with those acquired by conventional technique such as SIM and TEM has been demonstrated A crystallographic information about Al thin film is obtained by AFM using this technique.

Nonlinear Predictive Control of Transients in Automotive Variable Cam Timing Engine Using Nonlinear Parametric Approximation

2003 ◽  
Vol 125 (3) ◽  
pp. 429-438 ◽  
Author(s):  
Dimitry Gorinevsky ◽  
Jeffrey Cook ◽  
George Vukovich
Keyword(s):  
Controller Design ◽  
Finite Impulse Response ◽  
Feedforward Control ◽  
Linear Time ◽  
Practical Implementation ◽  
Automotive Engine ◽  
Model Free ◽  
Simplifying Assumptions ◽  
Control Application ◽  
Variable Cam Timing

The paper considers design of a predictive Linear Time Varying model-based controller with nonlinear feedforward for regulation of transient processes caused by setpoint step changes in a nonlinear plant. An optimal feedforward control sequence is computed based on an empirical Finite Impulse Response model of the process. Though the control techniques developed in this paper are meant to have more general industrial applicability, a specific automotive engine control application—control of Variable Cam Timing automotive engine—is pursued. An advantage of the proposed controller design in this problem is that no first principle models are required. Instead, nonlinear parametric approximations of a neural network type are being used to describe and identify static nonlinear mappings encountered in the problem. A number of simplifying assumptions and approximations are made to make practical implementation of the proposed scheme possible. Validity of the designed controller is verified by simulation. The proposed “model-free” design can potentially increase flexibility and save labor in development and deployment of such controllers for industrial systems.

Inversion-Based Feedforward Approach to Broadband Acoustic Noise Reduction

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Tom C. Waite ◽  
Qingze Zou ◽  
Atul Kelkar
Keyword(s):  
Noise Control ◽  
Feedforward Control ◽  
Acoustic Noise ◽  
Active Noise Control ◽  
Low Frequency ◽  
Control Technique ◽  
Frequency Range ◽  
Nonminimum Phase ◽  
Control Approach ◽  
Active Noise

In this article, an inversion-based feedforward control approach to achieve broadband active-noise control is investigated. Broadband active-noise control is needed in many areas, from heating, ventilation and air conditioning (HVAC) ducts to aircraft cabins. Achieving broadband active-noise control, however, is very challenging due to issues such as the complexity of acoustic dynamics (which has no natural roll-off at high frequency, and is often nonminimum phase), the wide frequency spectrum of the acoustic noise, and the critical requirement to overcome the delay of the control input relative to the noise signal. These issues have limited the success of existing feedforward control techniques to the low-frequency range of [0,1]kHz. The modeling issues in capturing the complex acoustic dynamics coupled with its nonminimum-phase characteristic also prevent the use of high-gain feedback methods, making the design of an effective controller to combat broadband noises challenging. In this article, we explore, through experiments, the potential of inversion-based feedforward control approach for noise control over the 1kHz low-frequency range limit. Then we account for the effect of modeling errors on the feedforward input by a recently developed inversion-based iterative control technique. Experimental results presented show that noise reduction of over 10–15dB can be achieved in a broad frequency range of 5kHz by using the inversion-based feedforward control technique.

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