Frequency Based Hysteresis Compensation for Piezoelectric Tube Scanner using Artificial Neural Networks

Asian Journal of Control

2018

In most nanotechnology applications, speed and precision are important requirements for obtaining good topographical maps of material surfaces using atomic force microscopes (AFMs), many of which use piezoelectric tube scanners (PTSs) for scanning and positioning at nanometric resolutions. For control engineers, the PTS is particularly interesting since its ability to enable the AFM to undertake 3D imaging is entirely dependent upon the use of a feedback loop. However, it suffers from various intrinsic problems that degrade its positioning performance, such as: (i) lightly damped low-frequency resonant modes due to its mechanical structure; (ii) nonlinear behavior due to hysteresis and creep; (iii) the cross-coupling effect between its axes (in 3D positioning systems such as AFMs); and (iv) effect of thermal drift. This article presents a survey of the literature on the PTS, an overview of a few existing innovative solutions for its nanopositioning and future research directions. This article will help the reader to walk around the present development of the PTS aimed at meeting the requirements for high-speed AFM imaging.

Section: Compensation Of Hysteresis Effectmentioning

confidence: 99%

Section: Innovative Solutions Of the Ptsmentioning

confidence: 99%

A Survey of Methods Used to Control Piezoelectric Tube Scanners in High‐Speed AFM Imaging

Asian Journal of Control

2018

“…It achieves better results than the Bouc-Wen and modified Prandtl-Ishlinskii (MPI) model-based ones as well as both the stand-alone controllers. Apart from model-based control methods, advanced controllers, such as the model predictive control (MPC) scheme [100], H ∞ [101], adaptive controller [102], [103], artificial neural networks (ANNs) [104], fuzzy logic control [105], repetitive control [106], sliding mode control [107], and iterative learning control (ILC) [97], have been designed to compensate the hysteresis effect in an AFM's PTS.…”

Section: ) Compensation Of Vibration Effectmentioning

confidence: 99%

Improvement in the Imaging Performance of Atomic Force Microscopy: A Survey

IEEE Trans. Automat. Sci. Eng.

2017

Nanotechnology is the branch of science which deals with the manipulation of matters at an extremely high resolution down to the atomic level. In recent years atomic force microscopy (AFM) has proven to be extremely versatile as an investigative tool in this field. The imaging performance of AFMs is hindered by: (i) the complex behavior of piezo materials, such as vibrations due to the lightly damped low-frequency resonant modes, inherent hysteresis and creep nonlinearities; (ii) the crosscoupling effect caused by the piezoelectric tube scanner (PTS); (iii) the limited bandwidth of the probe; (iv) the limitations of the conventional raster scanning method using a triangular reference signal; (v) the limited bandwidth of the proportionalintegral (PI) controllers used in AFMs; (vi) the offset, noise, and limited sensitivity of position sensors and photodetector; and(vii) limited sampling rate of AFM's measurement unit. Due to these limitations, an AFM has a high spatial but low temporal resolution, i.e., its imaging is slow, e.g., an image frame of a living cell takes up to 120 s, which means that rapid biological processes that occur in seconds cannot be studied using commercially available AFMs. There is a need, to perform fast scans using an AFM with nanoscale accuracy. This paper presents a survey of the literature, presents an overview of a few emerging innovative solutions in AFM imaging, and finally proposes future research directions. Note to Practitioners→ An atomic force microscope (AFM)is a scientific instrument capable of investigating, controlling, and manipulating matter on a nanoscale. It is a fundamental part of research in the field of nanotechnology because of its capability to obtain 3D images of specimens in the areas of life sciences and materials science. However, the imaging performances of currently available AFMs are restricted by some limitations which, during the last two decades, several works have attempted to overcome in order to meet present demands. This article presents an overview of developments in AFM imaging, emphasizing the key roles of: the modeling, control techniques, and mechanical structural designs of an AFM's piezoelectric tube scanner (PTS) and probe; different scanning methods; and sensor noise compensation techniques.

“…The effect of hysteresis varies according to the applied voltage amplitudes, with a hysteresis loop becoming wider with increasing amplitudes and frequencies of the applied voltage signal. Advanced controllers, such as the H ∞ , indirect adaptive control , artificial neural networks , and iterative learning control (ILC) have been designed to compensate for the hysteresis effect in an AFM's PTS. In , a complex Preisach hysteresis model is used to design a controller to control hysteresis but this controller produces distortions in scanned images at high frequencies because it does not take any steps to damp the resonant mode.…”

Section: Introductionmentioning

confidence: 99%

Effect of Improved Tracking for Atomic Force Microscope on Piezo Nonlinear Behavior

Asian Journal of Control

et al. 2014

Nanotechnology is an area of modern science which deals with the control of matter at dimensions of 100 nm or less. In recent years, of all the available microscopy techniques, atomic force microscopy (AFM) has proven to be extremely versatile as an investigative tool in this field. However the performance of AFM is significantly limited by the effects of hysteresis, creep, cross‐coupling, and vibration in its scanning unit, the piezoelectric tube scanner (PTS). This article presents the design and experimental implementation of a single‐input single‐output (SISO) model predictive control (MPC) scheme with a vibration compensator which is based on an identified model of the PTS. The proposed controller provides an AFM with the capability to achieve improved tracking and results in compensation of the nonlinear effects. The experimental results, which compare the tracking performances of the proposed controller for different reference signals, highlight the usefulness of the proposed control scheme.