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@article{Moore2019,
title = {Capacitive Instrumentation and Sensor Fusion for High-Bandwidth Nanopositioning},
author = {S. I. Moore and A. J. Fleming and Y. K. Yong},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2019/08/capsense.pdf},
year = {2019},
date = {2019-09-09},
journal = {IEEE Sensor Letters},
volume = {Accepted},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@inproceedings{Ragazzon2019,
title = {Generalized Lyapunov Demodulator for Amplitude and Phase Estimation by the Internal Model Principle},
author = {M. R. P. Ragazzon and S. Messineo and J. T. Gravdahl and D. M. Harcombe and M. G. Ruppert},
year = {2019},
date = {2019-09-04},
booktitle = {8th IFAC Symposium on Mechatronic Systems},
abstract = {Effective demodulation of amplitude and phase is a requirement in a wide array of applications. Recent efforts have increased the demodulation performance, in particular, the Lyapunov demodulator allows bandwidths up to the carrier frequency of the signal. However, being inherently restricted to a single order filtering of the input signal, signal components outside its passband are not sufficiently attenuated for all applications, such as in multifrequency atomic force microscopy. In this article, the structure of the Lyapunov demodulator is transformed to an equivalent form, taking advantage of the internal model representation of the sinusoid to be tracked. A generalization of this formulation allows the application of standard filtering techniques in order to shape the characteristics of the demodulator, while retaining the perfect tracking condition provided by the internal model. Guidelines for the filter design are provided in order to achieve the desired characteristics, such as filtering order, tracking bandwidth, and transient performance. The resulting generalized Lyapunov demodulator structure is highly flexible, allows for direct employment of any standard filter type, is computationally simple, and easy to implement requiring only a bandpass filter, a single integrator, and two nonlinear transformations. Numerical results demonstrate the effectiveness of the approach, and provide a comparison of the various filters considered.},
note = {accepted for publication},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}

@conference{McCourt2019,
title = {Resolution and Enhancement of Probes for Tip Enhanced Raman Spectroscopy},
author = {L. McCourt and B. S. Routley and M. G. Ruppert and A. J. Fleming},
year = {2019},
date = {2019-09-04},
booktitle = {International Conference on Nanophotonics and Micro/Nano Optics (NANOP)},
journal = {International Conference Nanophotonics and Micro/Nano Optics},
address = {Munich, Germany},
abstract = {Two photon apertureless nearfield lithography allows sub diffraction limited features for integrated circuit production. It involves exciting surface plasmons on a metallic atomic force microscopy probe, which generates an enhancement of the localised electric field, exposing a photoresist. Costing less than extreme ultra violet lithography, and reducing exposure from scattered light compared to one photon nearfield lithography, this technique is suited for device prototyping or low volume production. The work here considers the material and geometry of an ideal AFM probe in terms of resolution (producing the smallest features) and electric field enhancement.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}

@article{Moore2019c,
title = {An optimization framework for the design of piezoelectric AFM cantilevers},
author = {S. I. Moore and M. G. Ruppert and Y. K. Yong},
year = {2019},
date = {2019-08-15},
journal = {Precision Engineering},
volume = {60},
pages = {130-142},
abstract = {To facilitate further miniaturization of atomic force microscopy (AFM) cantilevers and to eliminate the standard optical beam deflection sensor, integrated piezoelectric actuation and sensing on the chip level is a promising option. This article presents a topology optimization method for dynamic mode AFM cantilevers that maximizes the sensitivity of an integrated piezoelectric sensor under stiffness and resonance frequency constraints. Included in the formulation is a new material model C-SIMP (connectivity and solid isotropic material with penalization) that extends the SIMP model to explicitly include the penalization of unconnected structures. Example cantilever designs demonstrate the potential of the topology optimization method. The results show, firstly, the C-SIMP material model significantly reduces connectivity issues and, secondly, arbitrary cantilever topologies can produce increases in sensor sensitivity or resonance frequency compared to a rectangular topology.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Moore2019,
title = {Design and Analysis of Low-Distortion Demodulators for Modulated Sensors},
author = { S. I. Moore and M. G. Ruppert and D. M. Harcombe and A. J. Fleming and Y. K. Yong },
url = {https://ieeexplore.ieee.org/document/8762188},
doi = {10.1109/TMECH.2019.2928592},
year = {2019},
date = {2019-07-17},
journal = {IEEE/ASME Transactions on Mechatronics},
volume = {24},
number = {4},
pages = {1861-1870},
abstract = {System-based demodulators in the form of a Kalman and Lyapunov filter have been demonstrated to significantly outperform traditional demodulators, such as the lock-in amplifier, in bandwidth sensitive applications, for example high-speed atomic force microscopy. Building on their closed loop architecture, this article describes a broader class of high-speed closed-loop demodulators. The generic structure provides greater flexibility to independently control the bandwidth and sensitivity to out-of-band frequencies. A linear time-invariant description is derived which allows the utilization of linear control theory to design the demodulator. Experimental results on a nanopositioner with capacitive sensors demonstrate the realization of arbitrary demodulator dynamics while achieving excellent noise rejection.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@inproceedings{C19d,
title = {Multivariable Model-less Feedforward Control of a Monolithic Nanopositioning Stage With FIR Filter Inversion},
author = {M. Omidbeike and A. A. Eielsen and Y. K. Yong and A. J. Fleming },
year = {2019},
date = {2019-07-02},
booktitle = {International Conference on Manipulation, Automation and Robotics at Small Scales (MARSS)},
address = {Helsinki, Finland},
abstract = {A model-less approach for inversion of the dynamics of multivariable systems using FIR filters is described. Inversion-based feedforward techniques have been widely used in the literature to achieve high-performance output tracking. The foremost difficulties associated with plant inversions are model uncertainties and non-minimum phase zeros. Various model-based methods have been proposed to exclude nonminimum phase zeros when inverting both single-input and single-output (SISO), and multiple-input and multiple-output (MIMO) systems. However, these methods increase the model uncertainty as they are no longer exact. To overcome these difficulties a model-less approach using FIR filters is presented. The results when applying the feedforward FIR filter to a multivariable nanopositioning system is presented, and they demonstrate the effectiveness of the feedforward technique in reducing the cross-coupling and achieving significantly improved output tracking.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}