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@article{J20c,
title = {Large-amplitude Dithering Mitigates Glitches in Digital-to-analogue Converters},
author = {A. A. Eielsen and J. Leth and A. J. Fleming and A. G. Wills and B. Ninness},
doi = {10.1109/TSP.2020.2978626},
isbn = {19410476},
year = {2020},
date = {2020-04-01},
journal = {IEEE Transactions on Signal Processing},
volume = {Early Access},
abstract = {Glitches introduce impulse-like disturbances which are not be readily attenuated by low-pass filtering. This article presents a model that describes the behaviour of glitches, and a method for mitigation based on a large-amplitude dither signal. Analytical and experimental results demonstrate that a dither signal with sufficient amplitude can mitigate the effect of glitches, when used in conjunction with a low-pass filter. The dither signal in conjunction with low-pass filtering essentially converts a glitch from a high-frequency to low-frequency disturbance.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{J20d,
title = {Electrode Configurations for Piezoelectric Tube Actuators With Improved Scan Range and Reduced Cross-Coupling},
author = {D. S. Raghunvanshi and S. I. Moore and A. J. Fleming and Y. K. Yong},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2020/03/Final-version-1.pdf},
doi = {10.1063/1.4981530},
issn = {00346748},
year = {2020},
date = {2020-03-24},
journal = {IEEE/ASME Transactions on Mechatronics},
volume = {(accepted)},
abstract = {Piezoelectric force and position sensors provide high sensitivity but are limited at low frequencies due to their high-pass response which complicates the direct application of integral control. To overcome this issue, an additional sensor or low-frequency correction method is typically employed. However, these approaches introduce an additional first-order response that must be higher than the high-pass response of the piezo and interface electronics. This article describes a simplified method for low-frequency correction that uses the piezoelectric sensor as an electrical component in a filter circuit. The resulting response is first-order, rather than second-order, with a cut-off frequency equal to that of a buffer circuit with the same input resistance. The proposed method is demonstrated to allow simultaneous damping and tracking control of a high-speed vertical nanopositioning stage.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Moore2020,
title = {AFM Cantilever Design for Multimode Q Control: Arbitrary Placement of Higher-Order Modes},
author = {S. I. Moore and M. G. Ruppert and Y. K. Yong},
url = {https://ieeexplore.ieee.org/document/9006926},
doi = {10.1109/TMECH.2020.2975627},
year = {2020},
date = {2020-02-21},
journal = { IEEE/ASME Transactions on Mechatronics},
pages = {1-6},
abstract = {In the fast growing field of multifrequency atomic force microscopy (AFM), the benefits of using higher-order modes has been extensively reported on. However, higher modes of AFM cantilevers are difficult to instrument and Q control is challenging owing to their high frequency nature. At these high frequencies, the latencies in the computations and analog conversions of digital signal processing platforms become significant and limit the effective bandwidth of digital feedback controller implementations. To address this issue, this article presents a novel cantilever design for which the first five modes are placed within a 200 kHz bandwidth. The proposed cantilever is designed using a structural optimization routine. The close spacing and low mechanical bandwidth of the resulting cantilever allows for the implementation of Q controllers for all five modes using a standard FPGA development board for bimodal AFM and imaging on higher-order modes.},
note = {Early Access},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Harcombe2020,
title = {A review of demodulation techniques for multifrequency atomic force microscopy},
author = {D. M. Harcombe and M. G. Ruppert and A. J. Fleming},
editor = {T. Glatzel},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2020/02/J20b-reducedSize.pdf},
doi = {doi:10.3762/bjnano.11.8},
issn = {21904286},
year = {2020},
date = {2020-01-07},
journal = {Beilstein Journal of Nanotechnology},
volume = {11},
pages = {76-97},
abstract = {This article compares the performance of traditional and recently proposed demodulators for multifrequency atomic force microscopy. The compared methods include the lock-in amplifier, coherent demodulator, Kalman filter, Lyapunov filter, and direct-design demodulator. Each method is implemented on a field-programmable gate array (FPGA) with a sampling rate of 1.5 MHz. The metrics for comparison include the sensitivity to other frequency components and the magnitude of demodulation artifacts for a range of demodulator bandwidths. Performance differences are demonstrated through higher harmonic atomic force microscopy imaging.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{J20a,
title = {Finite-Time Learning Control Using Frequency Response Data with Application to a Nanopositioning Stage},
author = {R. Rozario and A. J. Fleming and T. Oomen},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2020/02/J20a.pdf},
doi = {10.1109/TMECH.2019.2931407},
issn = {10834435},
year = {2020},
date = {2020-01-01},
journal = {IEEE/ASME Transactions on Mechatronics},
volume = {24},
number = {5},
pages = {2085-2096},
abstract = {Learning control enables significant performance improvement for systems that perform repeating tasks. Achieving high tracking performance by utilizing past error data typically requires noncausal learning that is based on a parametric model of the process. Such model-based approaches impose significant requirements on modeling and filter design. This paper aims to reduce these requirements by developing a learning control framework that enables performance improvement through noncausal learning without relying on a parametric model. This is achieved by explicitly using the discrete Fourier transform to enable learning by using a nonparametric frequency response function model of the process. The effectiveness of the developed method is illustrated by application to a nanopositioning stage},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@inproceedings{C19h,
title = {Image-Guided Locomotion of a Pneumatic-Driven Peristaltic Soft Robot},
author = {M. S. Xavier and A. J. Fleming and Y. K. Yong},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2020/05/C19g-reduced-1.pdf},
doi = {10.1109/ROBIO49542.2019.8961406},
isbn = {1-4244-0570-X},
year = {2019},
date = {2019-12-06},
booktitle = {IEEE International Conference on Robotics and Biomimetics},
address = {Dali, Yunnan, China},
abstract = {In this work, a pneumatic-driven peristaltic soft robot with pressure feedback control and image-guided tracking is developed. Locomotion is achieved in tube-like environments by mimicking the peristaltic motion of earthworms. The soft actuators are made of silicone rubber with 3D molding and fiber reinforcements. Pressure control is performed using custom made syringe pumps and on/off controllers in Arduino. Realtime visual tracking is accomplished in OpenCV with a colorbased approach. The soft robot has a stroke of 30-35mm for each cycle of actuation. This pneumatic soft robot shows great potential for application in minimally invasive surgery due to its compliance and biocompatibility.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}