Tracking of Triangular Reference Signals Using LQG Controllers for Lateral Positioning of an AFM Scanner Stage

Habibullah, Habibullah; Pota, H. R.; Petersen, Ian R.; Rana, M. S.

doi:10.1109/tmech.2013.2270560

Cited by 45 publications

(30 citation statements)

References 24 publications

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“…This compensator is designed to damp the first resonant mode of each of the PTSs. The general form of the vibration compensator and its design procedure is described in [4].…”

Section: Vibration Compensator Designmentioning

confidence: 99%

“…A piezoelectric tube actuator (PTA) is used in AFMs and the advantages of a piezoelectric material (PZM) is that it offers nanometer range motion without backlash, high stiffness, and fast response time [3]. The AFM has limitations in its high speed scanning because of the nature of piezoelectric tube scanners (PTSs) as it involves effects of hysteresis, creep, and vibration at high frequencies [4,5].…”

Section: Introductionmentioning

confidence: 99%

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Reduction of phase error between sinusoidal motions and vibration of a tube scanner during spiral scanning using an AFM

Habibullah

Pota

Petersen

2016

Int. J. Control Autom. Syst.

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The design of a phase-locked loop (PLL)-based proportional integral (PI) controller for compensating the phase error between motions from the lateral axes of a piezoelectric tube scanner (PTS) during spiral scanning for an atomic force microscope (AFM) is proposed in this paper. Spiral motion of the PTS for scanning of material surfaces or biological samples using an AFM is achieved by applying two sinusoidal signals with a 90 degree phase-shift and of varying amplitudes to the X and Y-axes of the scanner. The phase error between the X and Y-axes positions and scanner's vibration due to its mechanical properties increase with increasing scanning speeds which reduce the imaging performance of the AFM at high frequencies. In the proposed control scheme, a vibration compensator is used with the X and Y-PTS to damp the vibration of the PTS at its resonant frequency and the phase error between the displacements of the two lateral axes of the scanner is measured by a phase detector and a PI controller is used to reduce the error. Comparisons of experimental results for reference tracking and imaging performance with the AFM PI controller demonstrate the efficiency of the proposed control method.

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“…This compensator is designed to damp the first resonant mode of each of the PTSs. The general form of the vibration compensator and its design procedure is described in [4].…”

Section: Vibration Compensator Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reduction of phase error between sinusoidal motions and vibration of a tube scanner during spiral scanning using an AFM

Habibullah

Pota

Petersen

2016

Int. J. Control Autom. Syst.

Self Cite

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“…In traditional AFM imaging application, a periodic triangular signal is generally applied to its X-axis together with a staircase signal applied to its Y-axis [11]. However, there exist lots of problems in this scanning pattern: oscillations at the turning points will easily lead to system vibration and instability; this pattern is also time costing.…”

Section: Data Preprocessing Proceduresmentioning

confidence: 99%

“…Commonly employed in an atomic force microscope (AFM) [7] as a scanner, a PTS contributes a lot in micro/nano scale imaging and manipulations [8][9][10][11][12]. An AFM in contact constant-force mode works in the following way (see Fig.…”

Section: Introductionmentioning

confidence: 99%

“…For examples, Das et al apply a double resonant controller in [10] to damp out the first resonant mode of the PTS and increase the closed-loop bandwidth; an optimal linear quadratic Gaussian (LQG) controller with a vibration compensator is designed by Habibullah et al in [11] for the same purpose; Rana et al employ an improved model predictive control (MPC) scheme in [12] to achieve high-speed scanning performance. Although good tracking accuracy may be achieved by a well-designed feedback controller alone, a phase-lag between the control input and the plant response usually exists.…”

Section: Introductionmentioning

confidence: 99%

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Improved direct inverse tracking control of a piezoelectric tube scanner for high-speed AFM imaging

2015

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A Novel Application of Minimax LQG Control Technique for High‐speed Spiral Imaging

Habibullah

Pota

Petersen

2017

Asian Journal of Control

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Over the last two decades, increasing the scanning speed of an atomic force microscopy (AFM) has been attempted either by applying novel controllers, using alternative scanning methods, or by modifying the hardware setup. This paper demonstrates, the first two approaches to achieve high-speed AFM image scanning. A robust minimax linear quadratic Gaussian (LQG) controller is designed and spiral scanning is considered as an alternative scanning method rather than conventional raster scanning. The minimax LQG controller is designed based on an uncertain system model which is constructed by measuring the plant variations due to variations in sample mass and also modeling error between the measured and model frequency responses. This controller is also robust against uncertainties introduced as a result of variations of sample mass, spillover dynamics of the scanner at frequencies higher than the first resonance frequency of the scanner, and variation in plant transfer functions due to temperature and humidity. The designed controller is experimentally implemented on an AFM using a dSPACE ds-1103 real-time prototyping system and open-loop and closed-loop spiral imaging performances are evaluated. The proposed controller provides sufficient damping at the resonant modes to accurately track the sinusoidal reference signal and generate vibration free images. Also, creep, hysteresis, and cross-coupling effects are significantly reduced. The experimental results show that the proposed scheme outperforms the open-loop case and some other existing approaches.

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Tracking of Triangular Reference Signals Using LQG Controllers for Lateral Positioning of an AFM Scanner Stage

Cited by 45 publications

References 24 publications

Reduction of phase error between sinusoidal motions and vibration of a tube scanner during spiral scanning using an AFM

Reduction of phase error between sinusoidal motions and vibration of a tube scanner during spiral scanning using an AFM

Improved direct inverse tracking control of a piezoelectric tube scanner for high-speed AFM imaging

A Novel Application of Minimax LQG Control Technique for High‐speed Spiral Imaging

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