Publications

@article{J23a,

title = {Feasibility of gold nanocones for collocated tip-enhanced Raman spectroscopy and atomic force microscope imaging },

author = {L. R. McCourt and B. S. Routley and M. G. Ruppert and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2024/02/J23a-Preprint.pdf},

doi = {10.1002/jrs.6625},

issn = {1097-4555},

year  = {2024},

date = {2024-02-01},

urldate = {2024-02-01},

journal = {Journal of Raman Spectroscopy},

abstract = {Microcantilever probes for tip-enhanced Raman spectroscopy (TERS) have a grainy metal coating that may exhibit multiple plasmon hotspots near the tip apex, which may compromise spatial resolution and introduce imaging artefacts. It is also possible that the optical hotspot may not occur at the mechanical apex, which introduces an offset between TERS and atomic force microscope maps. In this article, a gold nanocone TERS probe is designed and fabricated for 638 nm excitation. The imaging performance is compared to grainy probes by analysing high-resolution TERS cross-sections of single-walled carbon nanotubes. Compared to the tested conventional TERS probes, the nanocone probe exhibited a narrow spot diameter, comparable optical contrast, artefact-free images, and collocation of TERS and atomic force microscope topographic maps. The spot diameter was 12.5 nm and 19 nm with 638 nm and 785 nm excitation, respectively. These results were acquired using a single gold nanocone probe to experimentally confirm feasibility. Future work will include automating the fabrication process and statistical analysis of many probes.},

keywords = {AFM, Cantilever, Optics},

pubstate = {forthcoming},

tppubtype = {article}

}

@article{J24b,

title = {Thermal Protection of Piezoelectric Actuators Using Complex Electrical Power Measurements and Simplified Thermal Models},

author = {Y. K. Yong and A. A. Eielsen and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2024/02/J24b-preprint.pdf},

doi = {10.1109/TMECH.2023.3277437},

isbn = {1083-4435},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

journal = {IEEE/ASME Transactions on Mechatronics},

abstract = {This article describes a method for estimating the temperature of high-power piezoelectric actuators when a direct temperature measurement is impractical. The heat flow is estimated from the real component of the electrical power; then, the temperature is estimated by a transfer function that approximates the thermal response of the system. The transfer function can be derived analytically from a lumped-element approximation or calibrated experimentally by using a system identification method. The proposed method is demonstrated on a piezoelectric stack actuator used in a high-speed nanopositioning device. A second-order transfer function estimates the temperature to within 3  ∘ C of a reference measurement for a range of operating conditions. The proposed method is suitable for protecting piezoelectric actuators in applications where direct temperature measurement is impractical, for example, due to space or wiring constraints.},

keywords = {piezoelectric, System Identification, Thermal},

pubstate = {forthcoming},

tppubtype = {article}

}

@article{J23a,

title = {Modeling of soft fluidic actuators using fluid-structure interaction simulations with underwater applications},

author = {M. S. Xavier and S. Harrison and D. Howard and Y. K. Yong and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2023/06/FSI.pdf},

doi = {10.1016/j.ijmecsci.2023.108437},

issn = {1879-2162},

year  = {2023},

date = {2023-05-15},

urldate = {2023-05-15},

journal = {International Journal of Mechanical Sciences},

volume = {255},

issue = {108437},

pages = {1-11},

abstract = {Soft robots have been developed for a variety of applications including gripping, locomotion, wearables and medical devices. For the majority of soft robots, actuation is performed using pneumatics or hydraulics. Many previous works have addressed the modeling of these fluid-driven soft robots using static finite element simulations where the pressure inside the actuator is assumed to be constant and uniform. The assumption of constant internal pressure is a useful simplification but introduces significant errors during events such as pressurization, depressurization, and transient loads from a liquid environment. Applications that use soft actuators for locomotion or propulsion operate using a sequence of transient events, so accurate simulation of these events is critical to optimizing performance. To improve the simulation of soft fluidic actuators and enable the modeling of both internal and external fluid flow in underwater applications, this work describes a fully-coupled, three-dimensional fluid–structure interaction simulation approach, where the pressure and flow dynamics are explicitly solved. This approach provides a realistic simulation of soft actuators in fluid environments, and permits the optimization of transient responses, which may be due to a combination of environmental fluid loads and non-uniform pressurization. The proposed methods are demonstrated in a number of case studies and experiments for a range of actuation and both internal and external inlet flow configurations, including bending actuators, a soft robotic fish fin for propulsion, and experimental results of a bending actuator in a high-speed fluid, which correlate closely with simulations. The proposed approach is expected to assist in the design, modeling, and optimization of bioinspired soft robots in underwater applications.},

keywords = {Finite element analysis, Fluid-structure interaction, Soft Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Single-Walled Carbon Nanotubes as One-Dimensional Scattering Surfaces for Measuring Point Spread Functions and Performance of Tip-Enhanced Raman Spectroscopy Probes},

author = {L. R. McCourt and B. S. Routley and M. G. Ruppert and V. J. Keast and C. I. Sathish and R. Borah and R. V. Goreham and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2023/02/J22i.pdf},

doi = {10.1021/acsanm.2c01274},

issn = {2574-0970},

year  = {2022},

date = {2022-06-21},

urldate = {2022-06-21},

journal = {ACS Applied Nano Materials},

volume = {5},

issue = {7},

pages = {9024-9033},

abstract = {This Article describes a method for the characterization of the imaging performance of tip-enhanced Raman spectroscopy probes. The proposed method identifies single-walled carbon nanotubes that are suitable as one-dimensional Raman scattering objects by using atomic force microscope maps and exciting the radial breathing mode using 785 nm illumination. High-resolution cross sections of the nanotubes are collected, and the point spread functions are calculated along with the optical contrast and spot diameter. The method is used to characterize several probes, which results in a set of imaging recommendations and a summary of limitations for each probe. Elemental analysis and boundary element simulations are used to explain the formation of multiple peaks in the point spread functions as a consequence of random grain formation on the probe surface.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Ragazzon2022,

title = {The Generalized Lyapunov Demodulator: High-Bandwidth, Low-Noise Amplitude and Phase Estimation},

author = {M. R. P. Ragazzon and S. Messineo and J. T. Gravdahl and D. M. Harcombe and M. G. Ruppert},

doi = {10.1109/OJCSYS.2022.3181111},

year  = {2022},

date = {2022-06-08},

urldate = {2022-06-08},

journal = {IEEE Open Journal of Control 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 first-order filtering of the input signal, it is highly sensitive to frequency components outside its passband region. This makes it unsuitable for certain applications such as multifrequency atomic force microscopy (AFM). In this article, the structure of the Lyapunov demodulator is transformed to an equivalent form and generalized by exploiting the internal model principle. The resulting generalized Lyapunov demodulator structure allows for arbitrary filtering order and is easy to implement, requiring only a bandpass filter, a single integrator, and two nonlinear transformations. The generalized Lyapunov demodulator is implemented experimentally on a field-programmable gate array (FPGA). Then it is used for imaging in an AFM and benchmarked against the standard Lyapunov demodulator and the widely used lock-in amplifier. The lock-in amplifier achieves great noise attenuation capabilities and off-mode rejection at low bandwidths, whereas the standard Lyapunov demodulator is shown to be effective at high bandwidths. We demonstrate that the proposed demodulator combines the best from the two state-of-the-art demodulators, demonstrating high bandwidths, large off-mode rejection, and excellent noise attenuation simultaneously.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{J22h,

title = {Soft Pneumatic Actuators: A Review of Design, Fabrication, Modeling, Sensing, Control and Applications},

author = {M. S. Xavier and C. D. Tawk and A. Zolfagharian and J. Pinskier and D. Howard and T. Young and J. Lai and S. Harrison and Y. K. Yong and M. Bodaghi and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2023/02/J22h-1.pdf},

doi = {10.1109/ACCESS.2022.3179589},

issn = {2169-3536},

year  = {2022},

date = {2022-06-02},

urldate = {2022-06-02},

journal = {IEEE Access},

volume = {10},

pages = {59442-59485},

abstract = {Soft robotics is a rapidly evolving field where robots are fabricated using highly deformable materials and usually follow a bioinspired design. Their high dexterity and safety makes them ideal for applications such as gripping, locomotion, and biomedical devices, where the environment is highly dynamic and sensitive to physical interaction. Pneumatic actuation remains the dominant technology in soft robotics due to its low cost and mass, fast response time, and easy implementation. Given the significant number of publications in soft robotics over recent years, newcomers and even established researchers may have difficulty assessing the state of the art. To address this issue, this article summarizes the development of soft pneumatic actuators and robots up until the date of publication. The scope of this article includes the design, modeling, fabrication, actuation, characterization, sensing, control, and applications of soft robotic devices. In addition to a historical overview, there is a special emphasis on recent advances such as novel designs, differential simulators, analytical and numerical modeling methods, topology optimization, data-driven modeling and control methods, hardware control boards, and nonlinear estimation and control techniques. Finally, the capabilities and limitations of soft pneumatic actuators and robots are discussed and directions for future research are identified.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{J22e,

title = {Nonlinear Estimation and Control of Bending Soft Pneumatic Actuators Using Feedback Linearization and UKF },

author = {M. S. Xavier and A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2023/02/J22e-1.pdf},

doi = {10.1109/TMECH.2022.3155790},

issn = {1083-4435},

year  = {2022},

date = {2022-06-01},

urldate = {2022-06-01},

journal = {IEEE/ASME Transactions on Mechatronics},

volume = {27},

issue = {4},

pages = {1919-1927},

abstract = {In this article, we combine nonlinear estimation and control methods for precise bending angle control in soft pneumatic actuators driven by a pressure source and single low-cost ON/OFF solenoid valve. First, a complete model for the soft actuator is derived, which includes both the motion and pressure dynamics. An unscented Kalman filter (UKF) is used to estimate the velocity state and filter noisy measurements from a pressure sensor and an embedded resistive flex sensor. Then, a feedback linearization approach is used with pole placement and linear quadratic regulator (LQR) controllers for bending angle control. To compensate for model uncertainties and improve reference tracking, integral action is incorporated to both controllers. The closed-loop performance of the nonlinear estimation and control approach is experimentally evaluated with a soft pneumatic network actuator. The simulation and experimental results show that the UKF provides accurate state estimation from noisy sensor measurements. The results demonstrate the effectiveness and robustness of the proposed observer-based nonlinear controllers for bending angle trajectory tracking.},

keywords = {Soft Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{J22g,

title = {Memory efficient constrained optimization of scanning-beam lithography},

author = {C. Jidling and A. J. Fleming and A. G. Wills and T. B. Schon},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/05/J22g.pdf},

doi = {10.1364/OE.457334},

issn = {1094-4087},

year  = {2022},

date = {2022-06-01},

journal = {Optics Express},

volume = {30},

number = {12},

pages = {20564--20579},

abstract = {This article describes a memory efficient method for solving large-scale optimization problems that arise when planning scanning-beam lithography processes. These processes require the identification of an exposure pattern that minimizes the difference between a desired and predicted output image, subject to constraints. The number of free variables is equal to the number of pixels, which can be on the order of millions or billions in practical applications. The proposed method splits the problem domain into a number of smaller overlapping subdomains with constrained boundary conditions, which are then solved sequentially using a constrained gradient search method (L-BFGS-B). Computational time is reduced by exploiting natural sparsity in the problem and employing the fast Fourier transform for efficient gradient calculation. When it comes to the trade-off between memory usage and computational time we can make a different trade-off compared to previous methods, where the required memory is reduced by approximately the number of subdomains at the cost of more computations. In an example problem with 30 million variables, the proposed method reduces memory requirements by 67%; but increases computation time by 27%. Variations of the proposed method are expected to find applications in the planning of processes such as scanning laser lithography, scanning electron beam lithography, and focused ion beam deposition, for example.},

keywords = {Optics},

pubstate = {published},

tppubtype = {article}

}

@article{J22f,

title = {High Performance Raster Scanning of Atomic Force Microscopy Using Model-free Repetitive Control},

author = {Linlin Li and A. J. Fleming and Y. K. Yong and S. S. Aphale and LiMin Zhu},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/08/J22f.pdf},

doi = {10.1016/j.ymssp.2022.109027},

issn = {0888-3270},

year  = {2022},

date = {2022-05-01},

urldate = {2022-05-01},

journal = {Mechanical Systems and Signal Processing},

volume = {173},

number = {109027},

abstract = {The image quality of an atomic force microscope depends on the tracking performance of the lateral X and Y axis positioner. To reduce the requirement for accurate system models, this article describes a method based on Model­ free Repetitive Control (MFRC) for high performance control of fast triangular trajectories in the X-axis, and a slow staircase trajectory in the Y-axis, while simultaneously achieving coupling compensation from the X-axis to Y-axis. The design and stability analysis of the MFRC scheme are presented in detail. The tracking results are experimen­ tally evaluated with a range of different load conditions, showing the efficacy of the method with large variations in plant dynamics. To address the coupling from the X-axis to the Y-axis while tracking the non-periodic staircase trajectories, a pre-learning step is used to generate the compensation signals, which is combined in a feedforward manner in real-time implementations. This approach is also applied to address the problem of longer convergence if needed. Experimental tracking control and coupling compensation is demonstrated on a commercially available piezoelectric-actuated scanner. The proposed method reduces the root-mean-square tracking from 191.4 nm in open­ loop or 194.6 nm with PI control, to 2.8 nm with PI+MFRC control at 100 Hz scan rate, which demonstrates the significant improvement achieved by the proposed method.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Tuning the enzyme-like activities of cerium oxide nanoparticles using a triethyl phosphite ligand},

author = {N. Yadav and V. Patel and L. McCourt and M. G. Ruppert and M. Miller and T. Inerbaev and S. Mahasivam and V. Bansal and A. Vinu and S. Singh and A. Karakoti},

doi = {10.1039/d2bm00396a},

year  = {2022},

date = {2022-04-22},

journal = {Royal Society of Chemistry: Biomaterials Science},

abstract = {Cerium oxide nanoparticles (CeNPs) exhibit excellent in vitro and in vivo antioxidant properties, determined by the redox switching of surface cerium ions between their two oxidation states (Ce3+ and Ce4+). It is known that ligands such as triethyl phosphite (TEP) can tune the redox behavior of CeNPs and change their biological enzyme-mimetic activities; however, the corresponding mechanism for such a behavior is completely unknown. Herein, we have studied the effect of TEP in promoting the SOD-enzyme-like activity in CeNPs with high and low Ce3+/Ce4+ ratio, which were synthesized by wet chemical and thermal hydrolysis methods, respectively, and incubated with varying concentrations of TEP. X-ray diffraction, UV-visible, photoluminescence, X-ray photoelectron spectroscopy, and Raman spectroscopy combined with DFT calculations were used to investigate the interaction of TEP on the surface of CeNPs. We observed a clear correlation between TEP concentration and the formation of surface oxygen vacancies. XPS analysis confirmed the increase in Ce3+ concentration after interaction with TEP. Moreover, we show that TEP's influence depends on the surface Ce3+/Ce4+ ratio. The superoxide dismutase-, catalase-, and oxidase-like activities of CeNPs with high Ce3+/Ce4+ ratio are not affected by TEP interaction, whereas catalase- and oxidase-like activities of CeNPs with low Ce3+/Ce4+ ratio decrease and the SOD-like activity is found to increase upon incubation with different concentrations of TEP. We also demonstrate that TEP interaction does not affect the regeneration of the CeNP surface, while the DFT calculations show that TEP facilitates the formation of defects on the surface of stoichiometric cerium oxide by reducing the oxygen vacancy formation energy. CeNPs with low Ce3+/Ce4+ ratio incubated with TEP also exhibited good antibacterial activity as compared to the CeNPs or TEP alone.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Chemical bond imaging using torsional and flexural higher eigenmodes of qPlus sensors},

author = {D. Martin-Jimenez and M. G. Ruppert and A. Ihle and S. Ahles and H. A. Wegner and A. Schirmeisen and D. Ebeling},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/04/Nanoscale-2022-Martin-Jimenez-bond-imaging-with-torsional-and-flexural-higher-eigenmodes.pdf},

doi = {10.1039/d2nr01062c},

year  = {2022},

date = {2022-03-23},

urldate = {2022-03-23},

journal = {Nanoscale - The Royal Society of Chemistry},

volume = {14},

number = {14},

pages = {5251-5628},

abstract = {Non-contact atomic force microscopy (AFM) with CO-functionalized tips allows to visualize the chemical structure of adsorbed molecules and identify individual inter- and intramolecular bonds. This technique enables in-depth studies of on-surface reactions and self-assembly processes. Herein, we analyze the suitability of qPlus sensors, which are commonly used for such studies, for the application of modern multifrequency AFM techniques. Two different qPlus sensors were tested for submolecular resolution imaging via actuating torsional and flexural higher eigenmodes and via bimodal AFM. The torsional eigenmode of one of our sensors is perfectly suited for performing lateral force microscopy (LFM) with single bond resolution. The obtained LFM images agree well with images from the literature, which were scanned with customized qPlus sensors that were specifically designed for LFM. The advantage of using a torsional eigenmode is that the same molecule can be imaged either with a vertically or laterally oscillating tip without replacing the sensor simply by actuating a different eigenmode. Submolecular resolution is also achieved by actuating the 2nd flexural eigenmode of our second sensor. In this case, we observe particular contrast features that only appear in the AFM images of the 2nd flexural eigenmode but not for the fundamental eigenmode. With complementary laser Doppler vibrometry measurements and AFM simulations we can rationalize that these contrast features are caused by a diagonal (i.e. in-phase vertical and lateral) oscillation of the AFM tip.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{J22d,

title = {Model-Based Nonlinear Feedback Controllers for Pressure Control of Soft Pneumatic Actuators Using On/Off Valves},

author = {M. S. Xavier and A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/03/J22d.pdf},

doi = {10.3389/frobt.2022.818187},

issn = {2296-9144},

year  = {2022},

date = {2022-03-17},

urldate = {2022-03-17},

journal = {Frontiers in Robotics and AI},

volume = {9},

abstract = {This article describes the application and comparison of three nonlinear feedback controllers for low-level control of soft actuators driven by a pressure source and single high-speed on/off solenoid valve. First, a mathematical model of the pneumatic system is established and the limitations of the open-loop system are evaluated. Next, a model of the pneumatic system is developed using Simscape Fluids to evaluate the performance of various control strategies. In this article, State-Dependent Riccati Equation control, sliding mode control, and feedback linearization are considered. To improve robustness to model uncertainties, the sliding mode and feedback linearization control strategies are augmented with integral action. The model of the pneumatic system is also used to develop a feedforward component, which is added to a PI controller with anti-windup. The simulation and experimental results demonstrate the effectiveness of the proposed controllers for pressure tracking.},

keywords = {Soft Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{J22a,

title = {Simultaneous tip force and displacement sensing for AFM cantilevers with on-chip actuation: Design and characterization for off-resonance tapping mode},

author = {N. F. S. de Bem and M. G. Ruppert and A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/03/J22a.pdf},

doi = {10.1016/j.sna.2022.113496},

issn = {0924-4247},

year  = {2022},

date = {2022-03-08},

urldate = {2022-03-08},

journal = {Sensors and Actuators A: Physical},

volume = {338},

pages = {113496},

abstract = {The use of integrated on-chip actuation simplifies the identification of a cantilever resonance, can improve imaging speed, and enables the use of smaller cantilevers, which is required for low-force imaging at high speed. This article describes a cantilever with on-chip actuation and novel dual-sensing capabilities for AFM. The dual-sensing configuration allows for tip displacement and tip force to be measured simultaneously. A mathematical model is developed and validated with finite element analysis. A physical prototype is presented, and its calibration and validation are presented. The cantilever is optimized for use in off-resonance tapping modes. Experimental results demonstrate an agreement between the on-chip sensors and external force and displacement measurements.},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {AFM, DP170101813},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2022,

title = {Experimental Analysis of Tip Vibrations at Higher Eigenmodes of QPlus Sensors for Atomic Force Microscopy},

author = {M. G. Ruppert and D. Martin-Jimenez and Y. K. Yong and A. Ihle and A. Schirmeisen and A. J. Fleming and D. Ebeling},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/03/J22c.pdf},

doi = {10.1088/1361-6528/ac4759},

issn = {1361-6528},

year  = {2022},

date = {2022-02-10},

urldate = {2022-02-10},

journal = {Nanotechnology},

volume = {33},

issue = {18},

pages = {185503},

abstract = {QPlus sensors are non-contact atomic force microscope probes constructed from a quartz tuning fork and a tungsten wire with an electrochemically etched tip. These probes are self-sensing and offer an atomic-scale spatial resolution. Therefore, qPlus sensors are routinely used to visualize the chemical structure of adsorbed organic molecules via the so-called bond imaging technique. This is achieved by functionalizing the AFM tip with a single CO molecule and exciting the sensor at the first vertical cantilever resonance mode. Recent work using higher-order resonance modes has also resolved the chemical structure of single organic molecules. However, in these experiments, the image contrast can differ significantly from the conventional bond imaging contrast, which was suspected to be caused by unknown vibrations of the tip. This work investigates the source of these artefacts by using a combination of mechanical simulation and laser vibrometry to characterize a range of sensors with different tip wire geometries. The results show that increased tip mass and length cause increased torsional rotation of the tuning fork beam due to the off-center mounting of the tip wire, and increased flexural vibration of the tip. These undesirable motions cause lateral deflection of the probe tip as it approaches the sample, which is rationalized to be the cause of the different image contrast. The results also provide a guide for future probe development to reduce these issues.},

note = {This work was supported in part by the Australian Research Council Discovery Project DP170101813},

keywords = {Actuator, AFM, Cantilever, DP170101813, Multifrequency AFM, piezoelectric},

pubstate = {published},

tppubtype = {article}

}

@article{Fleming2022,

title = {Piezoelectric Benders with Strain Sensing Electrodes: Sensor Design for Position Control and Force Estimation},

author = {R. Seethaler and S. Z. Mansour and M. G. Ruppert and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/03/J22b.pdf},

doi = {https://doi.org/10.1016/j.sna.2022.113384},

issn = {0924-4247},

year  = {2022},

date = {2022-01-22},

urldate = {2022-01-22},

journal = {Sensors and Actuators A: Physical},

volume = {335},

pages = {113384},

abstract = {Piezoelectric benders are widely used in industrial applications due to their low-cost and compact size. However, due to the large relative size and cost of displacement sensors, bender actuators are often operated in open-loop or with feed-forward control, which can limit positioning accuracy to 20% of full-scale. To improve the positioning accuracy of piezoelectric benders, this article proposes integrating resistive strain gauges into the electrode surface by chemical etching or laser ablation. These strain sensors are then used to measure and control the tip displacement. The proposed sensors are shown to suffer from significant cross-coupling between the actuator voltage and measured signal; however, this can be mitigated by judicious choice of the sensor location and actuator driving scheme. In addition to position sensing, a method is also presented for simultaneous estimation of the contact force between the actuator tip and load. The proposed methods are validated experimentally by controlling the tip position of a piezoelectric bender while simultaneously estimating the force applied to a reference load cell.},

keywords = {Actuator, piezoelectric},

pubstate = {published},

tppubtype = {article}

}

@article{Xavier2021,

title = {3D-printed omnidirectional soft pneumatic actuators: Design, modeling and characterization},

author = {M. S. Xavier and C. D. Tawk and Y. K. Yong and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/03/J21f.pdf},

doi = {10.1016/j.sna.2021.113199},

issn = {0924-4247},

year  = {2021},

date = {2021-12-25},

urldate = {2021-12-25},

journal = {Sensors and Actuators: A. Physical },

volume = {332},

issue = {2},

pages = {113199},

abstract = {Soft pneumatic actuators are usually fabricated using molding and casting techniques with silicone rubbers, which requires intensive manual labor and limits repeatability and design flexibility for complex geometries. This article presents the design and direct 3D-printing of novel omnidirectional soft pneumatic actuators using stereolithography (SLA) with an elastic resin and fused deposition modeling (FDM) with a thermoplastic polyurethane (TPU). The actuator is modeled and optimized for bending performance using the finite element method along with a hyperelastic material model that is based on experimental uniaxial tensile data. The designs inspired by fast pneumatic network actuators (PneuNets) allow for multimodal actuation including bending, extension and contraction motions under positive, negative or differential pressures. The predicted results from the finite element method are compared with the experimental results for a range of actuation configurations. These novel omnidirectional actuators have significant potential in applications such as pipe inspection and biomedical devices.},

keywords = {Soft Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{Omidbeike2021,

title = {Five-Axis Bimorph Monolithic Nanopositioning Stage: Design, Modeling, and Characterization},

author = {M. Omidbeike and S. I. Moore and Y. K. Yong and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/03/J21g.pdf},

doi = {10.1016/j.sna.2021.113125},

issn = {0924-4247},

year  = {2021},

date = {2021-09-16},

urldate = {2021-09-16},

journal = {Sensors and Actuators A: Physical},

volume = {332},

issue = {1},

abstract = {The article describes the design and modeling of a five-axis monolithic nanopositioning stage constructed from a bimorph piezoelectric sheet. Six-axis motion is also possible but requires 16 amplifier channels rather than 8. The nanopositioner is ultra low profile with a thickness of 1 mm. Analytical modeling and finite-element-analysis accurately predict the experimental performance. The stage was conservatively driven with 33% of the maximum voltage, which resulted in an X and Y travel range of 6.22 μm and 5.27 μm respectively; a Z travel range of 26.5 μm; and a rotational motion of 600 μrad and 884 μrad about the X and Y axis respectively. The first resonance frequency occurs at 883 Hz in the Z axis. Experimental atomic force microscopy is performed using the proposed device as a sample scanner.},

keywords = {AFM, Nanopositioning, piezoelectric},

pubstate = {published},

tppubtype = {article}

}

@article{J21d,

title = {Design and Control of Pneumatic Systems for Soft Robotics: a Simulation Approach},

author = {M. S. Xavier and A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/03/J21d.pdf},

doi = {10.1109/LRA.2021.3086425},

issn = {2377-3766},

year  = {2021},

date = {2021-06-04},

urldate = {2021-06-04},

journal = {IEEE Robotics and Automation Letters},

volume = {6},

issue = {3},

pages = {5800-5807},

abstract = {Pressure control plays a major role in the overall performance of fluid-driven soft robots. Due to the increasing demand for higher speed actuation and precision, a need exists for a practical design methodology that converts actuator performance specifications to a set of minimum pneumatic specifications, such as receiver volume and pressure, and valve conductance. This article presents a systematic parameter selection approach for pneumatic soft robotic systems by taking into consideration the desired closed-loop pressure responses. The two controllers under evaluation here are the PI controller with anti-windup and the on-off controller with hysteresis. Simulations are developed within Simscape Fluids to evaluate the effect of physical components and controller parameters on the actuator performance. The proposed parameter selection procedures are then applied on three soft actuators and their closed-loop pressure responses are experimentally evaluated. The measured pressure responses are in close agreement with the simulations and satisfy the rise time specifications.},

keywords = {Soft Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{J21e,

title = {Position and force sensing using strain gauges integrated into piezoelectric bender electrodes},

author = {R. Seethaler and S. Z. Mansour and M. G. Ruppert and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2022/03/J21e-1.pdf},

doi = {10.1016/j.sna.2020.112416},

isbn = {0924-4247},

year  = {2021},

date = {2021-04-15},

urldate = {2020-12-30},

journal = {Sensors and Actuators A: Physical},

volume = {321},

pages = {112416},

abstract = {This article derives design guidelines for integrating strain gauges into the electrodes of piezoelectric bending actuators. The proposed sensor can estimate the actuator tip displacement in response to an applied voltage and an external applied tip force. The actuator load force is also estimated with an accuracy of 8% full scale by approximating the actuator response with a linear model. The applications of this work include micro-grippers and pneumatic valves, which both require the measurement of deflection and load force. At present, this is achieved by external sensors. However, this work shows that these functions can be integrated into the actuator electrodes.},

keywords = {Actuator, Nanopositioning, piezoelectric},

pubstate = {published},

tppubtype = {article}

}

@article{Moore2021,

title = {Serial-kinematic monolithic nanopositioner with in-plane bender actuators},

author = {S. I. Moore and Y. K. Yong and M. Omidbeike and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2021/03/J21c.pdf},

doi = {https://doi.org/10.1016/j.mechatronics.2021.102541},

isbn = {0957-4158},

year  = {2021},

date = {2021-03-23},

journal = {Mechatronics},

volume = {75},

number = {102541},

abstract = {This article describes a monolithic nanopositioner constructed from in-plane bending actuators which provide greater deflection than previously reported extension actuators, at the expense of stiffness and resonance frequency. The proposed actuators are demonstrated by constructing an XY nanopositioning stage with a serial kinematic design. Analytical modeling and finite-element-analysis accurately predicts the experimental performance of the nanopositioner. A 10μm range is achieved in the X and Y axes with an applied voltage of +/-200 V. The first resonance mode occurs at 250 Hz in the Z axis. The stage is demonstrated for atomic force microscopy imaging.},

keywords = {Nanopositioning, piezoelectric},

pubstate = {published},

tppubtype = {article}

}

@article{J21b,

title = {Finite Element Modeling of Soft Fluidic Actuators: Overview and Recent Developments},

author = {M. S. Xavier and A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2021/02/J21b.pdf},

doi = {10.1002/aisy.202000187},

isbn = {2640-4567},

year  = {2021},

date = {2021-02-01},

journal = {Advanced Intelligent Systems},

volume = {3},

number = {2},

pages = {2000187},

abstract = {Many soft robots are composed of soft fluidic actuators that are fabricated from silicone rubbers and use hydraulic or pneumatic actuation. The strong nonlinearities and complex geometries of soft actuators hinder the development of analytical models to describe their motion. Finite element modeling provides an effective solution to this issue and allows the user to predict performance and optimize soft actuator designs. Herein, the literature on a finite element analysis of soft actuators is reviewed. First, the required nonlinear elasticity concepts are introduced with a focus on the relevant models for soft robotics. In particular, the procedure for determining material constants for the hyperelastic models from material testing and curve fitting is explored. Then, a comprehensive review of constitutive model parameters for the most widely used silicone rubbers in the literature is provided. An overview of the procedure is provided for three commercially available software packages (Abaqus, Ansys, and COMSOL). The combination of modeling procedures, material properties, and design guidelines presented in this article can be used as a starting point for soft robotic actuator design.},

keywords = {Soft Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2021,

title = {Active atomic force microscope cantilevers with integrated device layer piezoresistive sensors},

author = {M. G. Ruppert and A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2021/01/J21a.pdf},

doi = {10.1016/j.sna.2020.112519},

issn = {0924-4247},

year  = {2021},

date = {2021-01-19},

urldate = {2021-01-19},

journal = {Sensors & Actuators: A. Physical},

volume = {319},

pages = {112519},

abstract = {Active atomic force microscope cantilevers with on-chip actuation and sensing provide several advantages over

passive cantilevers which rely on piezoacoustic base-excitation and optical beam deflection measurement. Active

microcantilevers exhibit a clean frequency response, provide a path-way to miniturization and parallelization and

avoid the need for optical alignment. However, active microcantilevers are presently limited by the feedthrough

between actuators and sensors, and by the cost associated with custom microfabrication. In this work, we propose

a hybrid cantilever design with integrated piezoelectric actuators and a piezoresistive sensor fabricated from the

silicon device layer without requiring an additional doping step. As a result, the design can be fabricated using a

commercial five-mask microelectromechanical systems fabrication process. The theoretical piezoresistor sensitivity

is compared with finite element simulations and experimental results obtained from a prototype device. The

proposed approach is demonstrated to be a promising alternative to conventional microcantilever actuation and

deflection sensing},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {AFM, Cantilever, DP170101813, MEMS, Sensors, Smart Structures},

pubstate = {published},

tppubtype = {article}

}

@article{McCourt2020,

title = {A comparison of gold and silver nanocones and geometry optimisation for tip-enhanced microscopy},

author = {L. McCourt and M. G. Ruppert and B. S. Routley and S. Indirathankam and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2020/09/J20e.pdf},

doi = {https://doi.org/10.1002/jrs.5987},

year  = {2020},

date = {2020-11-01},

urldate = {2020-08-24},

journal = {Journal of Raman Spectroscopy},

volume = {51},

issue = {11},

pages = {2208-2216},

abstract = {In this article, boundary element method simulations are used to optimise the geometry of silver and gold nanocone probes to maximise the localised electric field enhancement and tune the near-field resonance wavelength. These objectives are expected to maximise the sensitivity of tip-enhanced Raman microscopes. Similar studies have used limited parameter sets or used a performance metric other than localised electric field enhancement. In this article, the optical responses for a range of nanocone geometries are simulated for excitation wavelengths ranging from 400 to 1000 nm. Performance is evaluated by measuring the electric field enhancement at the sample surface with a resonant illumination wavelength. These results are then used to determine empirical models and derive optimal nanocone geometries for a particular illumination wavelength and tip material. This article concludes that gold nanocones are expected to provide similar performance to silver nanocones at red and nearinfrared wavelengths, which is consistent with other results in the literature. In this article, 633 nm is determined to be the shortest usable illumination wavelength for gold nanocones. Below this limit, silver nanocones will provide superior enhancement. The use of gold nanocone probes is expected to dramatically improve probe lifetime, which is currently measured in hours for silver coated probes. Furthermore, the elimination of passivation coatings is expected to enable smaller probe radii and improved topographical resolution.},

keywords = {AFM, Cantilever, MEMS, Optics, SPM},

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 = {https://www.precisionmechatronicslab.com/wp-content/uploads/2020/09/J20d.pdf},

doi = {10.1109/TMECH.2020.2978241},

issn = {00346748},

year  = {2020},

date = {2020-06-01},

journal = {IEEE/ASME Transactions on Mechatronics},

volume = {25},

number = {3},

pages = {1479-1486},

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 = {Actuator, Nanopositioning, piezoelectric, Piezoelectric Transducers and Drives},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2020,

title = {Amplitude Noise Spectrum of a Lock-in Amplifier: Application to Microcantilever Noise Measurements},

author = {M. G. Ruppert and N. J. Bartlett and Y. K. Yong and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2020/09/J20f.pdf},

doi = {10.1016/j.sna.2020.112092},

year  = {2020},

date = {2020-05-29},

urldate = {2020-05-29},

journal = {Sensors and Actuators A: Physical},

volume = {312},

pages = {112092},

abstract = {The lock-in amplifier is a crucial component in many applications requiring high-resolution displacement sensing; it's purpose is to estimate the amplitude and phase of a periodic signal, potentially corrupted by noise, at a frequency determined by a reference signal. Where the noise can be approximated by a stationary Gaussian process, such as thermal force noise and electronic sensor noise, this article derives the amplitude noise spectral density of the lock-in-amplifier output. The proposed method is demonstrated by predicting the demodulated noise spectrum of a microcantilever for dynamic-mode atomic force microscopy to determine the cantilever on-resonance thermal noise, the cantilever tracking bandwidth and the electronic noise floor. The estimates are shown to closely match experimental results over a wide range of operating conditions.},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {AFM, Cantilever, Demodulation, DP170101813, MEMS, System Identification},

pubstate = {published},

tppubtype = {article}

}

@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},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2020/06/J20c.pdf},

doi = {10.1109/TSP.2020.2978626},

issn = {19410476},

year  = {2020},

date = {2020-04-01},

journal = {IEEE Transactions on Signal Processing},

volume = {68},

pages = {1950-1963},

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 = {DACs},

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},

urldate = {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 = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {AFM, Cantilever, DP170101813, MEMS, Multifrequency AFM, Smart Structures, SPM, Vibration Control},

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 = {https://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 = {AFM, Demodulation, Multifrequency AFM, SPM},

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 = {https://www.precisionmechatronicslab.com/wp-content/uploads/2020/09/J20a-1.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 = {Nanopositioning, Tracking Control},

pubstate = {published},

tppubtype = {article}

}

@article{Wang2019b,

title = {Scan Rate Adaptation for AFM Imaging Based on Performance Metric Optimisation},

author = {K. Wang and M. G. Ruppert and C. Manzie and D. Nesic and Y. K. Yong },

url = {https://ieeexplore.ieee.org/document/8867937},

doi = {10.1109/TMECH.2019.2947203},

year  = {2019},

date = {2019-10-14},

journal = { IEEE/ASME Transactions on Mechatronics},

abstract = {Constant-force contact-mode atomic force microscopy (AFM) relies on a feedback control system to regulate the tip-sample interaction during imaging. Due to limitations in actuators and control, the bandwidth of the regulation system is typically small. Therefore, the scan rate is usually limited in order to guarantee a desirable image quality for a constant-rate scan. By adapting the scan rate online, further performance improvement is possible, and the conditions to this improvement has been explored qualitatively in a previous study for a wide class of possible scan patterns. In this paper, a quantitative assessment of the previously proposed adaptive scan scheme is investigated through experiments that explore the impact of various degrees of freedom in the algorithm. Further modifications to the existing scheme are proposed and shown to improve the closed-loop performance. The flexibility of the proposed approach is further demonstrated by applying the algorithm to tapping-mode AFM.},

note = {early access},

keywords = {AFM, Nanopositioning, Scan Pattern, SPM, Tracking Control},

pubstate = {published},

tppubtype = {article}

}

@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 = {https://www.precisionmechatronicslab.com/wp-content/uploads/2019/10/J19c.pdf},

doi = {10.1109/LSENS.2019.2933065},

isbn = {2475-1472},

year  = {2019},

date = {2019-09-09},

journal = {IEEE Sensor Letters},

volume = {3},

number = {8},

pages = {2501503},

abstract = {Precision capacitive sensing methods encode the measurement in a high frequency signal, which requires demodulation. To extract the measurement, the signal is observed over many cycles limiting the bandwidth of the sensor and introducing an undesirable phase lag. To address this limitation, this article outlines a design, which fuses the output of a standard modulated capacitive sensor and a charge amplifier, providing an instantaneous capacitive measurement whose bandwidth is only limited by the speed at which the electronics operate.},

keywords = {Nanopositioning, Sensors},

pubstate = {published},

tppubtype = {article}

}

@article{J19e,

title = {Scanning Laser Lithography with Constrained Quadratic Exposure Optimization},

author = {A. J. Fleming and O. T. Ghalehbeygi and B. S. Routley and A. G. Wills},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2020/02/J19e.pdf},

doi = {10.1109/TCST.2018.2836910},

isbn = {1063-6536},

year  = {2019},

date = {2019-09-01},

journal = {IEEE Transactions on Control Systems Technology},

volume = {27},

number = {5},

pages = {2221-2228},

abstract = {Scanning laser lithography is a maskless lithography method for selectively exposing features on a film of photoresist. A set of exposure positions and beam energies are required to optimally reproduce the desired feature pattern. The task of determining the exposure energies is inherently non-linear due to the photoresist model and the requirement for only positive energy. In this article, a nonlinear programming approach is employed to find an optimal exposure profile that minimizes the feature error and total exposure energy. This method is demonstrated experimentally to create a features with sub-wavelength geometry.},

keywords = {Lithography},

pubstate = {published},

tppubtype = {article}

}

@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},

url = {https://www.sciencedirect.com/science/article/pii/S0141635919302260},

year  = {2019},

date = {2019-08-15},

urldate = {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.},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {AFM, Cantilever, DP170101813, MEMS, Piezoelectric Transducers and Drives, Smart Structures, SPM},

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://www.precisionmechatronicslab.com/wp-content/uploads/2020/05/J19d-reduced.pdf},

doi = {10.1109/TMECH.2019.2928592},

issn = {10834435},

year  = {2019},

date = {2019-07-17},

urldate = {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.},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {Demodulation, DP170101813, Multifrequency AFM, Nanopositioning, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{Wang2019,

title = {Adaptive Scan for Atomic Force Microscopy Based on Online Optimisation: Theory and Experiment},

author = {K. Wang and M. G. Ruppert and C. Manzie and D. Nesic and Y. K. Yong},

url = {https://ieeexplore.ieee.org/document/8643730},

year  = {2019},

date = {2019-01-31},

journal = {IEEE Transactions on Control System Technology},

abstract = {A major challenge in Atomic Force Microscopy

(AFM) is to reduce the scan duration while retaining the

image quality. Conventionally, the scan rate is restricted to a

sufficiently small value in order to ensure a desirable image

quality as well as a safe tip-sample contact force. This usually

results in a conservative scan rate for samples that have a

large variation in aspect ratio and/or for scan patterns that

have a varying linear velocity. In this paper, an adaptive scan

scheme is proposed to alleviate this problem. A scan line-based

performance metric balancing both imaging speed and accuracy

is proposed, and the scan rate is adapted such that the metric

is optimised online in the presence of aspect ratio and/or linear

velocity variations. The online optimisation is achieved using an

extremum-seeking (ES) approach, and a semi-global practical

asymptotic stability (SGPAS) result is shown for the overall

system. Finally, the proposed scheme is demonstrated via both

simulation and experiment.},

note = {accepted for publication},

keywords = {AFM, Nanopositioning, SPM, System Identification, Tracking Control},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2018b,

title = {Multimodal atomic force microscopy with optimized higher eigenmode sensitivity using on-chip piezoelectric actuation and sensing},

author = {M. G. Ruppert and S. I. Moore and M. Zawierta and A. J. Fleming and G. Putrino and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2019/08/Ruppert_2019_Nanotechnology_30_085503.pdf},

doi = {https://doi.org/10.1088/1361-6528/aae40b},

year  = {2019},

date = {2019-01-02},

urldate = {2019-01-02},

journal = {Nanotechnology},

volume = {30},

number = {8},

pages = {085503},

abstract = {Atomic force microscope (AFM) cantilevers with integrated actuation and sensing provide several distinct advantages over conventional cantilever instrumentation. These include clean frequency responses, the possibility of down-scaling and parallelization to cantilever arrays as well as the absence of optical interference. While cantilever microfabrication technology has continuously advanced over the years, the overall design has remained largely unchanged; a passive rectangular shaped cantilever design has been adopted as the industry wide standard. In this article, we demonstrate multimode AFM imaging on higher eigenmodes as well as bimodal AFM imaging with cantilevers using fully integrated piezoelectric actuation and sensing. The cantilever design maximizes the higher eigenmode deflection sensitivity by optimizing the transducer layout according to the strain mode shape. Without the need for feedthrough cancellation, the read-out method achieves close to zero actuator/sensor feedthrough and the sensitivity is sufficient to resolve the cantilever Brownian motion.},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {AFM, Cantilever, DP170101813, MEMS, Multifrequency AFM, Piezoelectric Transducers and Drives, Sensors, Smart Structures, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{J18f,

title = {A Comparison Of Scanning Methods And The Vertical Control Implications For Scanning Probe Microscopy},

author = {Y. R. Teo and Y. K. Yong and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2021/02/J18f.pdf},

doi = {10.1002/asjc.1422},

year  = {2018},

date = {2018-07-01},

journal = {Asian Journal of Control},

volume = {30},

number = {4},

pages = {1-15},

abstract = {This article compares the imaging performance of non-traditional scanning patterns for scanning probe microscopy including sinusoidal raster, spiral, and Lissajous patterns. The metrics under consideration include the probe velocity, scanning frequency, and required sampling rate. The probe velocity is investigated in detail as this quantity is proportional to the required bandwidth of the vertical feedback loop and has a major impact on image quality. By considering a sample with an impulsive Fourier transform, the effect of scanning trajectories on imaging quality can be observed and quantified. The non-linear trajectories are found to spread the topography signal bandwidth which has important implications for both low and high-speed imaging. These effects are studied analytically and demonstrated experimentally with a periodic calibration grating. },

keywords = {Scan Pattern, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{J18e,

title = {Piezoelectric Bimorph Actuator with Integrated Strain Sensing Electrodes},

author = {S. Z. Mansour and R. J. Seethaler and Y. R. Teo and Y. K. Yong and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2021/02/J18e.pdf},

doi = {10.1109/JSEN.2018.2842138},

issn = {1530-437X},

year  = {2018},

date = {2018-07-01},

journal = {IEEE Sensors Journal},

volume = {18},

number = {4},

abstract = {This article describes a new method for estimating the tip displacement of piezoelectric benders. Two resistive strain gauges are fabricated within the top and bottom electrodes using an acid etching process. These strain gauges are employed in a half bridge electrical configuration to measure the surface resistance change, and estimate the tip displacement. Experimental validation shows a 1.1 % maximum difference between the strain sensor and a laser triangulation sensor. Using the presented method, a damping-integral control structure is designed to control the tip displacement of the integrated bender},

keywords = {Piezoelectric Transducers and Drives},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2018b,

title = {Self-sensing, estimation and control in multifrequency Atomic Force Microscopy. },

author = {M. G. Ruppert},

url = {https://royalsoc.org.au/images/pdf/journal/151-1-Ruppert.pdf},

issn = {0035-9173/18/010111-01},

year  = {2018},

date = {2018-06-01},

journal = {Journal & Proceedings of the Royal Society of New South Wales},

volume = {151},

number = {1},

pages = {111},

abstract = {Despite the undeniable success of the atomic force  microscope  (AFM),  dynamic  techniques still face limitations in terms of spatial resolution, imaging speed and high cost of acquisition. In order to expand the capabilities  of  the  instrument,  it  was  realized  that the information about the nano-mechanical properties  of  a  sample  are  encoded  over  a range of frequencies and the excitation and detection of higher-order eigenmodes of the micro-cantilever  open  up  further  informa-

tion  channels.  The  ability  to  control  these modes and their fast responses to excitation is believed to be the key to unravelling the true potential of these ethods. This work addresses  three  major  drawbacks  of  the standard AFM setup, which limit the feasibility of multi-frequency approaches.



First,   microelectromechanical   system (MEMS)  probes  with  integrated  piezoelectric layers is motivated, enabling the development of novel multimode self-sensing and self-actuating techniques. Specifically, these piezoelectric  transduction  schemes  permit the  miniaturization  of  the  entire  AFM towards  a  cost-effective  single-chip  device with nanoscale precision in a much smaller form factor than that of conventional macroscale instruments.



Second, the integrated actuation enables the development of multimode controllers which  exhibits  remarkable  performance  in arbitrarily  modifying  the  quality  factor  of multiple eigenmodes and comes with inherent  stability  robustness.  The  experimental results  demonstrate  improved  imaging  stability,  higher  scan  speeds  and  adjustable contrast  when  mapping  nano-mechanical properties of soft samples. 



Last, in light of the demand for constantly increasing  imaging  speeds  while  providing multi-frequency flexibility, the estimation of multiple components of the high-frequency deflection signal is performed with a linear time-varying multi-frequency Kalman filter. The chosen representation allows for an efficient high-bandwidth implementation on a Field  Programmable  Gate  Array. Tracking bandwidth, noise performance and trimodal AFM imaging on a two-component polymer sample  are  verified  and  shown  to  be  superior to that of the commonly used lock-in amplifier.},

keywords = {Cantilever, MEMS, Multifrequency AFM, Sensors, Smart Structures, SPM, System Identification, Vibration Control},

pubstate = {published},

tppubtype = {article}

}

@article{J18g,

title = {Improving Robustness Filter Bandwidth in Repetitive Control by Considering Model Mismatch},

author = {A. A. Eielsen and Y. R. Teo and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2021/02/J18g.pdf},

doi = {10.1002/asjc.1437},

issn = {1934-6093},

year  = {2018},

date = {2018-05-01},

journal = {Asian Journal of Control},

volume = {20},

number = {3},

pages = {1-11},

abstract = {Repetitive control (RC) is used to track and reject periodic signals by including a model of a periodic signal in the feedback path. The performance of RC can be improved by including an inverse plant response filter, but due to modeling uncertainty at high frequencies, a low-pass robustness filter is also required to limit the bandwidth of the signal model and ensure stability. The design of robustness filters is presently ad-hoc, which may result in excessively conservative performance. This article proposes a new automatic method for designing the robustness filter based on convex optimization and an uncertainty model. Experimental results on a nanopositioning system demonstrate that the proposed method outperforms the traditional brick-wall filter approach.},

keywords = {Nanopositioning},

pubstate = {published},

tppubtype = {article}

}

@article{J18c,

title = {Lyapunov Estimation for High-Speed Demodulation in Multifrequency Atomic Force Microscopy},

author = {D. M. Harcombe and M. G. Ruppert and M. R. P. Ragazzon and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2018/02/J18c.pdf},

doi = {10.3762/bjnano.9.47},

issn = {21904286},

year  = {2018},

date = {2018-02-28},

journal = {Beilstein Journal of Nanotechnology},

volume = {9},

pages = {490-498},

abstract = {An important issue in the emerging field of multifrequency atomic force microscopy (MF-AFM) is the accurate and fast demodulation of the cantilever-tip deflection signal. As this signal consists of multiple frequency components and noise processes, a lock-in amplifier is typically employed for its narrowband response. However, this demodulator suffers inherent bandwidth limitations as high frequency mixing products must be filtered out and several must be operated in parallel. Many MF-AFM methods require amplitude and phase demodulation at multiple frequencies of interest, enabling both z-axis feedback and phase contrast imaging to be achieved. This article proposes a model-based multifrequency Lyapunov filter implemented on a Field Programmable Gate Array (FPGA) for high-speed MF-AFM demodulation. System descriptions and simulations are verified by experimental results demonstrating high tracking bandwidths, strong off-mode rejection and minor sensitivity to cross-coupling effects. Additionally, a five-frequency system operating at 3.5MHz is implemented for higher harmonic amplitude and phase imaging up to 1MHz.},

keywords = {AFM, Multifrequency AFM},

pubstate = {published},

tppubtype = {article}

}

@article{J18a,

title = {Monolithic Piezoelectric Insect with Resonance Walking},

author = {S. A. Rios and A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2021/02/J18a.pdf},

doi = {10.1109/tmech.2018.2792618},

issn = {10834435},

year  = {2018},

date = {2018-02-01},

journal = {IEEE/ASME Transactions on Mechatronics},

volume = {23},

number = {2},

pages = {524-530},

abstract = {This article describes the design, manufacture and performance of an untethered hexapod robot titled MinRAR V2. This robot utilizes a monolithic piezoelectric element, machined to allow for individual activation of bending actuators. The legs were designed so that the first two resonance modes overlap and therefore produce a walking motion at resonance. The monolithic construction significantly improves the matching of resonance modes between legs when compared to previous designs. Miniature control and high voltage driving electronics were designed to drive 24 separate piezoelectric elements powered from a single 3.7 V lithium polymer battery. The robot was driven both tethered and untethered and was able to achieve a maximum forward velocity of 98 mm/s when driven at 190 Hz and 6 mm/s at 5 Hz untethered. The robot is capable of a wide range of movements including banking, on the spot turning and reverse motion.},

keywords = {Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{Bazaei2018,

title = {A Novel State Transformation Approach to Tracking of Piecewise Linear Trajectories},

author = {A. Bazaei and Z. Cheng and Y. K. Yong and S. O. R. Moheimani},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/05/07851084.pdf},

doi = {10.1109/TCST.2017.2654061},

year  = {2018},

date = {2018-01-01},

journal = {IEEE Transactions on Control Systems Technology},

volume = {26},

number = {1},

pages = {128 - 138},

abstract = {In this paper, we propose a novel approach for tracking of piecewise linear trajectories, such as triangular and staircase waveforms. We derive state and input transformations, which result in closed-loop error dynamics driven by a series of impulses. The proposed control structure takes the form of an output-feedback-feedforward system that is straightforward to implement. In contrast to the recently proposed tracking control methods for such trajectories, the closed-loop stability is not affected by the frequency of the desired triangular reference.

The method is implemented on a nanopositioner serving as the

scanning stage of an atomic force microscope.},

keywords = {Nanopositioning, Tracking Control},

pubstate = {published},

tppubtype = {article}

}

@article{J18b,

title = {Resonance-enhanced Coupling for Range Extension of Electromagnetic Tracking Systems},

author = {M. N. Islam and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2021/02/J18b.pdf},

doi = {10.1109/tmag.2017.2784384},

issn = {00189464},

year  = {2018},

date = {2018-01-01},

journal = {IEEE Transactions on Magnetics},

volume = {54},

number = {4},

pages = {1-9},

abstract = {This article investigates the use of resonance-enhanced coupling to increase the received signal level in a six degree-of-freedom electromagnetic tracking system. Resonant coupling is found to increase the efficiency of the transmitter and increase the gain of the sensing coil, resulting in improved range. However, the measurement update rate is reduced due to the settling-time of the transmitter circuit and limited bandwidth of the sensing circuit. A resistive tuning approach is proposed to balance the trade-off between a decreased measurement bandwidth and improved signal level.},

keywords = {Biomedical},

pubstate = {published},

tppubtype = {article}

}

@article{J17k,

title = {An Ultra-thin Monolithic XY Nanopositioning Stage Constructed from a Single Sheet of Piezoelectric Material},

author = {A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2018/01/J17k.pdf},

doi = {10.1109/TMECH.2017.2755659},

isbn = {1083-4435},

year  = {2017},

date = {2017-12-20},

journal = {IEEE/ASME Transactions on Mechatronics},

volume = {22},

number = {6},

pages = {2611-2618},

abstract = {The article describes an XY nanopositioning stage constructed from flexures and actuators machined into a single sheet of piezoelectric material. Ultrasonic machining is used to remove piezoelectric material and create electrode features. The constructed device is 0.508mm thick and has a travel range of 8.8um in the X and Y axes. The first resonance mode occurs at 597Hz which makes the device suitable for a wide range of standard nanopositioning applications where cost and size are considerations. Experimental atomic force microscopy is performed using the proposed device as a sample scanner.},

keywords = {AFM, Nanopositioning},

pubstate = {published},

tppubtype = {article}

}

@article{J17i,

title = {Existing Methods for Improving the Accuracy of Digital-to-Analog Converters},

author = {A. A. Eielsen and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/08/J17i.pdf},

doi = {10.1063/1.5000974},

year  = {2017},

date = {2017-10-01},

journal = {Review of Scientific Instruments},

volume = {88},

pages = {094702},

abstract = {The performance of digital-to-analog converters is principally limited by errors in the output voltage levels. Such errors are known as element mismatch and are quantified by the integral non-linearity. Element mismatch limits the achievable accuracy and resolution in high-precision applications as it causes gain and offset error, as well as harmonic distortion. In this article, five existing methods for mitigating the effects of element mismatch are compared: physical level calibration, dynamic element matching, noise-shaping with digital calibration, large periodic high-frequency dithering, and large stochastic high-pass dithering. These methods are suitable for improving accuracy when using digital-to-analog converters that use multiple discrete output levels to reconstruct time-varying signals. The methods improve linearity and therefore reduce harmonic distortion, and can be retrofitted to existing systems with minor hardware variations. The performance of each method is compared theoretically and confirmed by simulations and experiments. Experimental results demonstrate that three of the five methods provide significant improvements in the resolution and accuracy when applied to a general-purpose digital-to-analog converter. As such, these methods can directly improve performance in a wide range of applications including nanopositioning, metrology, and optics.},

keywords = {DACs},

pubstate = {published},

tppubtype = {article}

}

@article{J17h,

title = {A Review of Demodulation Techniques for Amplitude Modulation Atomic Force Microscopy},

author = {M. G. Ruppert and D. M. Harcombe and M. R. P. Ragazzon and S. O. R. Moheimani and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2020/08/2190-4286-8-142.pdf},

doi = {10.3762/bjnano.8.142},

year  = {2017},

date = {2017-09-01},

journal = {Bellstein Journal of Nanotechnology},

volume = {8},

pages = {1407–1426},

abstract = {In this review paper, traditional and novel demodulation methods applicable to amplitude modulation atomic force microscopy are implemented on a widely used digital processing system. As a crucial bandwidth-limiting component in the z-axis feedback loop of an atomic force microscope, the purpose of the demodulator is to obtain estimates of amplitude and phase of the cantilever deflection signal in the presence of sensor noise or additional distinct frequency components. Specifically for modern multifrequency techniques, where higher harmonic and/or higher eigenmode contributions are present in the oscillation signal, the fidelity of the estimates obtained from some demodulation techniques is not guaranteed. To enable a rigorous comparison, the performance metrics tracking bandwidth, implementation complexity and sensitivity to other frequency components are experimentally evaluated for each method. Finally, the significance of an adequate demodulator bandwidth is highlighted during high-speed tapping-mode AFM experiments in constant height mode.},

keywords = {AFM, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{J17j,

title = {Gradient-based optimization for efficient exposure planning in maskless lithography},

author = {O. T. Ghalehbeygi and A. G. Wills and B. S. Routley and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/09/J17j.pdf},

doi = {10.1117/1.JMM.16.3.033507},

year  = {2017},

date = {2017-09-01},

journal = {Journal of  Micro/Nanolithography, MEMS, and MOEMS},

volume = {16},

number = {3},

pages = {033507},

abstract = {Scanning laser lithography is a maskless method for exposing photoresist during semiconductor manufacturing. In this method, the energy of a focused beam is controlled while scanning the beam or substrate. With a positive photoresist material, areas that receive an exposure dosage over the threshold energy are dissolved during development. The surface dosage is related to the exposure profile by a convolution and nonlinear function, so the optimal exposure profile is nontrivial. A gradient-based optimization method for determining an optimal exposure profile, given the desired pattern and models of the beam profile and photochemistry, is described. This approach is more numerically efficient than optimal barrier-function-based methods but provides near-identical results. This is demonstrated through simulation and experimental lithography},

keywords = {Lithography},

pubstate = {published},

tppubtype = {article}

}

@article{J17g,

title = {An Algorithm for Transmitter Optimization in Electromagnetic Tracking Systems},

author = {M. N. Islam and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/05/07926412.pdf},

doi = {10.1109/TMAG.2017.2703653},

isbn = {0018-9464},

year  = {2017},

date = {2017-08-30},

journal = {IEEE Transactions on Magnetics},

volume = {53},

number = {8},

pages = {1-8},

abstract = {Electromagnetic tracking systems are used extensively in biomedical devices, gaming consoles, and animation because they are inexpensive and do not require line of sight. However, the measurement range is limited by the amplitude of the induced voltage in the sensing coil. The induced voltage is a function of the transmitter parameters such as the coil dimensions, signal power, and frequency. The transmitted power is typically restricted by the physical constraints in the application. This paper develops an algorithm to optimize the dimensions of the transmitting coil for maximum induced voltage. The proposed method is suitable for a transmitter consisting of three concentric orthogonal transmitting coils of the type commonly used in six-degree-of-freedom localization. The simulation and experimental results are presented, which demonstrate the efficacy of the proposed method.},

keywords = {Biomedical},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2017b,

title = {Note: Guaranteed collocated multimode control of an atomic force microscope cantilever using on-chip piezoelectric actuation and sensing},

author = {M. G. Ruppert and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/08/2017_JNote_RSI_Vol88_086109-2.pdf},

doi = {10.1063/1.4990451},

year  = {2017},

date = {2017-08-15},

urldate = {2017-08-15},

journal = {Review of Scientific Instruments},

volume = {88},

number = {086109},

abstract = {The quality (Q) factor is an important parameter of the resonance of the microcantilever as it determines

both imaging bandwidth and force sensitivity. The ability to control the Q factor of multiple

modes is believed to be of great benefit for atomic force microscopy techniques involving multiple

eigenmodes. In this paper, we propose a novel cantilever design employing multiple piezoelectric

transducers which are used for separated actuation and sensing, leading to guaranteed collocation

of the first eight eigenmodes up to 3 MHz. The design minimizes the feedthrough usually observed

with these systems by incorporating a guard trace on the cantilever chip. As a result, a multimode

Q controller is demonstrated to be able to modify the quality factor of the first two eigenmodes over

up to four orders of magnitude without sacrificing robust stability.},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {AFM, Cantilever, DP170101813, MEMS, Multifrequency AFM, Piezoelectric Transducers and Drives, System Identification, Vibration Control},

pubstate = {published},

tppubtype = {article}

}

@article{J17f,

title = {An Improved Low-frequency Correction Technique for Piezoelectric Force Sensors in High-speed Nanopositioning Systems},

author = {Y. K. Yong and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/08/Yong2017_note.pdf},

year  = {2017},

date = {2017-08-02},

journal = {Review of Scientific Instruments},

volume = {88},

number = {046105},

pages = {1-3},

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 = {Nanopositioning},

pubstate = {published},

tppubtype = {article}

}

@article{J17e,

title = {Lyapunov Estimator for High-Speed Demodulation in Dynamic Mode Atomic Force Microscopy},

author = {M. R. P. Ragazzon and M. G. Ruppert and D. M. Harcombe and A. J. Fleming and J. T. Gravdahl},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/09/J17e.pdf},

year  = {2017},

date = {2017-08-01},

journal = {IEEE Transactions on Control Systems Technology},

volume = {26},

number = {2},

pages = {765-772},

abstract = {In dynamic mode atomic force microscopy (AFM), the imaging bandwidth is governed by the slowest component in the open-loop chain consisting of the vertical actuator, cantilever and demodulator. While the common demodulation method is to use a lock-in amplifier (LIA), its performance is ultimately bounded by the bandwidth of the post-mixing low-pass filters. This article proposes an amplitude and phase estimation method based on a strictly positive real Lyapunov design approach. The estimator is designed to be of low complexity while allowing for high bandwidth. Additionally, suitable gains for high performance are suggested such that no tuning is necessary. The Lyapunov estimator is experimentally implemented for amplitude demodulation and shown to surpass the LIA in terms of tracking bandwidth and noise performance. High-speed AFM images are presented to corroborate the results.},

keywords = {AFM, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{J17c,

title = {Improving Digital-to-analog Converter Linearity by Large High-frequency Dithering},

author = {A. A. Eielsen and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2020/06/J17c.pdf},

doi = {10.1109/TCSI.2016.2561778},

issn = {1549-8328},

year  = {2017},

date = {2017-07-01},

journal = {IEEE Transactions on Circuits and Systems I},

volume = {64},

number = {6},

pages = {1409-1420},

abstract = {A new method for reducing harmonic distortion due to element mismatch in digital-to-analog converters is described. This is achieved by using a large high-frequency periodic dither. The reduction in non-linearity is due to the smoothing effect this dither has on the non-linearity, which is only dependent on the amplitude distribution function of the dither. Since the high-frequency dither is unwanted on the output on the digital-to-analog converter, the dither is removed by an output filter. The fundamental frequency component of the dither is attenuated by a passive notch filter and the remaining fundamental component and harmonic components are attenuated by the low-pass reconstruction filter. Two methods that further improve performance are also presented. By reproducing the dither on a second channel and subtracting it using a differential amplifier, additional dither attenuation is achieved; and by averaging several channels, the noise-floor of the output is improved. Experimental results demonstrate more than 10 dB improvement in the signal-to-noise-and-distortion ratio.},

keywords = {DACs},

pubstate = {published},

tppubtype = {article}

}

@article{Moore2017,

title = {Design and Characterization of Cantilevers for Multi-Frequency Atomic Force Microscopy},

author = {S. I. Moore and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/01/MNL.2016.0586.pdf},

doi = {10.1049/mnl.2016.0586},

year  = {2017},

date = {2017-03-01},

urldate = {2017-03-01},

journal = {Micro & Nano Letters},

volume = {12},

number = {5},

pages = {315-320},

abstract = {The experimental characterisation of a set of microcantilevers targeted at use in multi-frequency atomic force microscope is presented. The aim of this work is to design a cantilever that naturally amplifies its harmonic oscillations which are introduced by nonlinear probe–sample

interaction forces. This is performed by placing the modal frequencies of the cantilever at integer multiples of the first modal frequency. The developed routine demonstrates the placement of the frequency of the second to fifth mode. The characterisation shows a trend that

lower-order modes are more accurately placed than higher-order modes. With two fabricated designs, the error in the second mode is at most 2.26% while the greatest error in the fifth mode is at 10.5%.},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {Cantilever, DP170101813, MEMS, Multifrequency AFM, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{Moore2017b,

title = {Multimodal cantilevers with novel piezoelectric layer topology for sensitivity enhancement},

author = {S. I. Moore and M. G. Ruppert and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/02/2190-4286-8-38.pdf},

year  = {2017},

date = {2017-02-06},

urldate = {2017-02-06},

journal = {Beilstein Journal of Nanotechnology},

volume = {8},

pages = {358--371},

abstract = {Self-sensing techniques for atomic force microscope (AFM) cantilevers have several advantageous characteristics compared to the optical beam deflection method. The possibility of down scaling, parallelization of cantilever arrays and the absence of optical interference associated imaging artifacts have led to an increased research interest in these methods. However, for multifrequency AFM, the optimization of the transducer layout on the cantilever for higher order modes has not been addressed. To fully utilize an integrated piezoelectric transducer, this work alters the layout of the piezoelectric layer to maximize both the deflection of the cantilever and measured piezoelectric charge response for a given mode with respect to the spatial distribution of the strain. On a prototype cantilever design, significant increases in actuator and sensor sensitivities were achieved for the first four modes without any substantial increase in sensor noise. The transduction mechanism is specifically targeted at multifrequency AFM and has the potential to provide higher resolution imaging on higher order modes.},

note = {This work was supported by the Australian Research Council Discovery Project DP170101813},

keywords = {Cantilever, DP170101813, Multifrequency AFM, Piezoelectric Transducers and Drives, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{Bazaei2017,

title = {Combining Spiral Scanning and Internal Model Control for Sequential AFM Imaging at Video Rate},

author = {A. Bazaei and Y. K. Yong and S. O. R. Moheimani },

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/05/07482697.pdf},

year  = {2017},

date = {2017-02-01},

journal = {IEEE Transactions on Mechatronics},

volume = {22},

number = {1},

pages = {371-380},

abstract = {We report on the application of internal model control for accurate tracking of a spiral trajectory for atomic force microscopy (AFM). With a closed-loop bandwidth of only 300 Hz, we achieved tracking errors as low as 0.31% of the scan diameter and an ultravideo frame rate for a high pitch (30 nm) spiral trajectory generated by amplitude modulation of 3 kHz sinusoids. Design and synthesis procedures are proposed for a smooth modulating waveform to minimize the steady-state tracking error during sequential imaging. To obtain AFM images under the constant force condition, a high bandwidth analogue proportional integral controller is applied to the damped z-axis of a flexure nanopositioner. Efficacy of the proposed method was  demonstrated by artifact-free images at a rate of 37.5 frames/s.},

keywords = {Scan Pattern, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2017,

title = {On-chip Dynamic Mode Atomic Force Microscopy: A silicon-on-insulator MEMS approach},

author = {M. G. Ruppert and A. G. Fowler and M. Maroufi and S. O. R. Moheimani},

doi = {10.1109/JMEMS.2016.2628890},

year  = {2017},

date = {2017-02-01},

journal = {IEEE Journal of Microelectromechanical Systems},

volume = {26},

number = {1},

pages = {215-225},

abstract = {The atomic force microscope (AFM) is an invaluable scientific tool; however, its conventional implementation as a relatively costly macroscale system is a barrier to its more widespread use. A microelectromechanical systems (MEMS) approach to AFM design has the potential to significantly reduce the cost and complexity of the AFM, expanding its utility beyond current applications. This paper presents an on-chip AFM based on a silicon-on-insulator MEMS fabrication process. The device features integrated xy electrostatic actuators and electrothermal sensors as well as an AlN piezoelectric layer for out-of-plane actuation and integrated deflection sensing of a microcantilever. The three-degree-of-freedom design allows the probe scanner to obtain topographic tapping-mode AFM images with an imaging range of up to 8μm x 8μm in closed loop.},

keywords = {MEMS, Nanopositioning, Piezoelectric Transducers and Drives, Sensors, Smart Structures, SPM, Tracking Control},

pubstate = {published},

tppubtype = {article}

}

@article{J17a,

title = {Miniature Resonant Ambulatory Robot},

author = {S. A. Rios and A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/01/J17a.pdf},

doi = {10.1109/LRA.2016.2614837},

issn = {2377-3766},

year  = {2017},

date = {2017-01-01},

journal = {IEEE Robotics and Automation Letters},

volume = {2},

number = {1},

pages = {337--343},

abstract = {This article describes the design, manufacture, and performance of a prototype miniature resonant ambulatory robot that uses piezoelectric actuators to achieve locomotion. Each leg is comprised of two piezoelectric bimorph benders, joined at the tip by a flexure and end effector. Combinations of amplitude and phase can be used to produce a wide range of motions including swinging and lifting. A lumped mass model previously developed is described as a design tool to tune the resonance modes of the end effector. The completed robot was driven with frequencies up to 500 Hz resulting in a maximum forward velocity of approximately 520 mm/s at 350 Hz. A frequency analysis was also performed to determine the effects of ground contact on the performance of the robot. This analysis showed a significant reduction in the resonance gain and frequency.},

keywords = {Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{Yong2016c,

title = {Preloading Piezoelectric Stack Actuator in High-speed Nanopositioning Systems},

author = {Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2016/11/fmech-02-00008-1.pdf},

year  = {2016},

date = {2016-12-12},

journal = {Frontiers in Mechanical Engineering},

volume = {2},

pages = {1-9},

abstract = {Recent development in high-speed nanotechnology applications, such as scanning probe microscopy and nanofabrication, has increased interest on the advancement of high-bandwidth flexure-guided nanopositioning systems. These systems are capable of providing motions with sub-nanometer resolution over a positioning bandwidth of a few kilohertz or more. High-speed nanopositioning devices are commonly driven by compact and stiff piezoelectric stack actuators. However, these actuators are highly sensitive to tensile and lateral forces. During high-speed operations, excessive inertia force due to the effective mass of nanopositioning system could potentially damage the actuator. To protect the piezoelectric actuator, preload is often applied to compensate for these inertial forces. This article surveys key challenges in existing preload techniques in the context of high-speed nanopositioning designs, and explores how these challenges can be overcome.},

keywords = {Nanopositioning},

pubstate = {published},

tppubtype = {article}

}

@article{J16b,

title = {Exposure Optimization in Scanning Laser Lithography},

author = {A. J. Fleming and A. G. Wills and B. S. Routley},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2016/08/J16b.pdf},

doi = {10.1109/MPOT.2016.2540039},

issn = {0278-6648},

year  = {2016},

date = {2016-12-01},

journal = {IEEE Potentials},

volume = {35},

number = {4},

pages = {33-39},

keywords = {Lithography},

pubstate = {published},

tppubtype = {article}

}

@article{J16d,

title = {High-speed Vertical Positioning Stage with Integrated Dual-sensor Arrangement},

author = {Y. K. Yong and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2016/08/1-s2.0-S0924424716303302-main-1.pdf},

doi = {https://doi.org/10.1016/j.sna.2016.06.042},

year  = {2016},

date = {2016-12-01},

journal = {Sensors & Actuators: A. Physical},

volume = {248},

pages = {184--192},

abstract = {This article presents a novel vertical positioning stage with a dual-sensor arrangement suitable for scanning probe microscopy. The stage has a travel range of 8.4um and a first resonance frequency of 24kHz in the direction of travel. The sensor arrangement consists of an integrated piezoelectric force sensor and laminated piezoresistive strain sensor. The piezoelectric force sensor exhibits extremely low noise and introduces a zero into the dynamics which allows the use of integral force feedback. This control method provides excellent damping performance and guaranteed stability. The piezoresistive sensor is used for tracking control with an analog PI controller which is shown to be an approximate inverse of the damped system. The resulting closed-loop system has a bandwidth is 11.4kHz and 6-sigma resolution of 3.6nm, which is ideal for nanopositioning and atomic force microscopy (AFM) applications. The proposed vertical stage is used to replace the vertical axis of a commercial AFM. Scans are performed in constant-force contact mode with a tip velocity of 0.2mm/s, 1mm/s and 2mm/s. The recorded images contain negligible artefacts due to insufficient vertical bandwidth.},

keywords = {Nanopositioning, Optics, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2016,

title = {High-Bandwidth Demodulation in MF-AFM: A Kalman Filtering Approach},

author = {M. G. Ruppert and D. M. Harcombe and S. O. R. Moheimani},

doi = {10.1109/TMECH.2016.2574640},

year  = {2016},

date = {2016-12-01},

journal = {IEEE/ASME Transactions on Mechatronics},

volume = {21},

number = {6},

pages = {2705-2715},

abstract = {Emerging multifrequency atomic force microscopy (MF-AFM) methods rely on coherent demodulation of the cantilever deflection signal at multiple frequencies. These measurements are needed in order to close the z-axis feedback loop and to acquire complementary information on the tip-sample interaction. While the common method is to use a lock-in amplifier capable of recovering low-level signals from noisy backgrounds, its performance is ultimately bounded by the bandwidth of the low-pass filters. In light of the demand for constantly increasing imaging speeds while providing multifrequency flexibility, we propose to estimate the in-phase and quadrature components with a linear time-varying Kalman filter. The chosen representation allows for an efficient high-bandwidth implementation on a Field Programmable Gate Array (FPGA). Tracking bandwidth and noise performance are verified experimentally and trimodal AFM results on a two-component polymer sample highlight the applicability of the proposed method for MF-AFM.},

keywords = {Multifrequency AFM, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{J16e,

title = {High-Speed Single-Stage and Dual-Stage Vertical Positioners},

author = {Y. K. Yong and S. P. Wadikhaye and A. J. Fleming },

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/01/J16e.pdf},

year  = {2016},

date = {2016-09-01},

journal = {Review of Scientific Instruments},

volume = {87},

number = {085104},

pages = {(1-8)},

abstract = {This article presents a high-speed single- and dual-stage vertical positioner for applications in optical systems. Each positioner employs a unique end-constraint method with orthogonal flexures to preload a piezoelectric stack actuator. This end-constraint method also significantly increases the first mechanical resonance frequency. The single-stage positioner has a displacement range of 7.6um and a first resonance frequency of 46.8kHz. The dual-stage design consists of a long-range slow-stage and a short-range fast-stage. An inertial counterbalance technique was implemented on the fast-stage to cancel inertial forces resulting from high-speed motion. The dual-stage positioner has a combined travel range of approximately 10um and a first evident resonance frequency of 130kHz.},

keywords = {Nanopositioning, Optics},

pubstate = {published},

tppubtype = {article}

}

@article{J16c,

title = {A Simplified Method For Discrete-Time Repetitive Control Using Model-Less FIR Filter Inversion},

author = {Y. R. Teo and A. A. Eielsen and J. T. Gravdahl and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2016/06/J16c.pdf},

doi = {10.1115/1.4033274},

year  = {2016},

date = {2016-08-01},

journal = {Journal of Dynamic Systems, Measurement and Control},

volume = {138},

number = {8},

pages = {081002},

abstract = {Repetitive control (RC) achieves tracking and rejection of periodic exogenous signals by incorporating a model of a periodic signal in the feedback path. To improve the performance, an inverse plant response filter (IPRF) is used. To improve robustness, the periodic signal model is bandwidth-limited. This limitation is largely dependent on the accuracy of the IPRF. A new method is presented for synthesizing the IPRF for discrete-time RC. The method produces filters in a simpler and more consistent manner than existing best-practice methods available in the literature, as the only variable involved is the selection of a windowing function. It is also more efficient in terms of memory and computational complexity than existing methods. Experimental results for a nanopositioning stage show that the proposed method yields the same or better tracking performance compared to existing methods.},

keywords = {Nanopositioning},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2016b,

title = {Multimode Q Control in Tapping-Mode AFM: Enabling Imaging on Higher Flexural Eigenmodes},

author = {M. G. Ruppert and S. O. R. Moheimani},

doi = {10.1109/TCST.2015.2478077},

year  = {2016},

date = {2016-07-01},

journal = {IEEE Transactions on Control Systems Technology},

volume = {24},

number = {4},

pages = {1149-1159},

abstract = {Numerous dynamic Atomic Force Microscopy (AFM) methods have appeared in recent years, which make use of the excitation and detection of higher order eigenmodes of the microcantilever. The ability to control these modes and their responses to excitation is believed to be the key to unraveling the true potential of these methods. In this work, we highlight a multi-mode Q control method that exhibits remarkable damping performance and stability robustness. The experimental results obtained in ambient conditions demonstrate improved imaging stability by damping non-driven resonant modes when scanning is performed at a higher eigenmode of the cantilever. Higher scan speeds are shown to result from a decrease in transient response time. },

keywords = {MEMS, Multifrequency AFM, SPM, System Identification, Vibration Control},

pubstate = {published},

tppubtype = {article}

}

@article{Yong2016b,

title = {A new preload mechanism for a high-speed piezoelectric stack nanopositioner},

author = {Y. K. Yong},

url = {http://www.eng.newcastle.edu.au/~yy582/Papers/Yong2016_preload.pdf},

year  = {2016},

date = {2016-04-13},

journal = {Mechatronics},

volume = {36},

pages = {159-166},

abstract = {Piezoelectric stack actuators are the actuator of choice for many ultra-high precision systems owning to its fast responses and high pushing force capabilities. These actuators are constructed by bonding multiple piezoelectric layers together. An inevitable drawback of these actuators is that there are highly intolerant to tensile and shear forces. During high-speed operations, inertial forces due to effective mass of the system cause the actuators to experience excessive tensile forces. To avoid damage to the actuators, preload must be applied to compensate for these forces. In many nanopositioning systems, flexures are used to provide preload to the piezoelectric stack actuators. However, for high-speed systems with stiff flexures, displacing the flexures and sliding the actuators in place to preload them is a difficult task. One may reduce the stiffness of the flexures to make the preload process more feasible; however, this reduces the mechanical bandwidth of the system. This paper presents a novel preload mechanism that tackles the limitations mentioned above. The preload stage, which is connected in parallel mechanically to a high-speed vertical nanopositioner, allows the piezoelectric stack actuator to be installed and preloaded easily without significantly trading of the stiffness and speed of the nanopositioning system. The proposed vertical nanopositioner has a travel range of 10.6 μ m. Its first resonant mode appears at about 24 kHz along

the actuation direction.},

keywords = {Nanopositioning},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2016b,

title = {High-bandwidth Multimode Self-sensing in Bimodal Atomic Force Microscopy},

author = {M. G. Ruppert and S. O. R. Moheimani},

doi = {10.3762/bjnano.7.26},

year  = {2016},

date = {2016-02-24},

journal = {Beilstein Journal of Nanotechnology},

volume = {7},

pages = {284-295},

abstract = {Using standard microelectromechanical system (MEMS) processes to coat a microcantilever with a piezoelectric layer results in a versatile transducer with inherent self-sensing capabilities. For applications in multifrequency atomic force microscopy (MF-AFM), we illustrate that a single piezoelectric layer can be simultaneously used for multimode excitation and detection of the cantilever deflection. This is achieved by a charge sensor with a bandwidth of 10 MHz and dual feedthrough cancellation to recover the resonant modes that are heavily buried in feedthrough originating from the piezoelectric capacitance. The setup enables the omission of the commonly used piezoelectric stack actuator and optical beam deflection sensor, alleviating limitations due to distorted frequency responses and instrumentation cost, respectively. The proposed method benefits from a more than two orders of magnitude increase in deflection to strain sensitivity on the fifth eigenmode leading to a remarkable signal-to-noise ratio. Experimental results using bimodal AFM imaging on a two component polymer sample validate that the self-sensing scheme can therefore be used to provide both the feedback signal, for topography imaging on the fundamental mode, and phase imaging on the higher eigenmode.},

keywords = {MEMS, Multifrequency AFM, Piezoelectric Transducers and Drives, Vibration Control},

pubstate = {published},

tppubtype = {article}

}

@article{J16f,

title = {Design of a Charge Drive for Reducing Hysteresis in a Piezoelectric Bimorph Actuator},

author = {S. A. Rios and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2017/01/J16f.pdf},

doi = {10.1109/TMECH.2015.2483739},

year  = {2016},

date = {2016-02-01},

journal = {IEEE/ASME Transactions on Mechatronics},

volume = {21},

number = {1},

pages = {51-54},

abstract = {This article describes the design of a charge drive for reducing the hysteresis exhibited by a piezoelectric bimorph bender. Existing charge drive circuits cannot be directly applied to bimorph benders since they share a common electrode. In this article a new charge drive circuit and electrical configuration is implemented that allows commonly available piezoelectric bimorphs to be linearized. This circuit consists of four major components, including, a high voltage amplifier, a differential amplifier, a piezoelectric load and a PI feedback controller. An isolation amplifier was used to achieve a differential amplifier with a high common-mode rejection ratio. The charge drive was tested by driving a series poled, three layer bimorph bender. The results demonstrate that the use of a charge drive can reduce the hysteresis from 26.8% to 2.1%. This work has identified an alternative feedforward method to improve the AC hysteresis performance of a piezoelectric bender by using a charge drive.},

keywords = {Piezoelectric Transducers and Drives, Robotics},

pubstate = {published},

tppubtype = {article}

}

@article{Ruppert2016b,

title = {A Kalman Filter for Amplitude Estimation in High-Speed Dynamic Mode Atomic Force Microscopy},

author = {M. G. Ruppert and K. S. Karvinen and S. L. Wiggins and S. O. R. Moheimani},

doi = {10.1109/TCST.2015.2435654},

year  = {2016},

date = {2016-01-01},

journal = {IEEE Transactions on Control Systems Technology},

volume = {24},

number = {1},

pages = {276-284},

abstract = {A fundamental challenge in dynamic mode atomic force microscopy (AFM) is the estimation of the cantilever oscillation amplitude from the deflection signal which might be distorted by noise and/or high-frequency components. When the cantilever is excited at resonance, its deflection is typically obtained via narrowband demodulation using a lock-in amplifier. However, the bandwidth of this measurement technique is ultimately bounded by the low-pass filter which must be employed after demodulation to attenuate the component at twice the carrier frequency. Furthermore, to measure the amplitude of multiple frequency components such as higher eigenmodes and/or higher harmonics in multifrequency AFM, multiple lock-in amplifiers must be employed. In this work, the authors propose the estimation of amplitude and phase using a linear time-varying Kalman filter which is easily extended to multiple frequencies. Experimental results are obtained using square-modulated sine waves and closed-loop AFM scans, verifying the performance of the proposed Kalman filter.},

keywords = {Multifrequency AFM, SPM, Vibration Control},

pubstate = {published},

tppubtype = {article}

}

@article{J15f,

title = {A Closed-Loop Phase-Locked Interferometer for Wide Bandwidth Position Sensing},

author = {A. J. Fleming and B. S. Routley},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2015/12/J15f.pdf},

doi = {10.1063/1.4935469},

year  = {2015},

date = {2015-12-31},

journal = {Review of Scientific Instruments},

volume = {86},

pages = {115001(1-7)},

abstract = {This article describes a position sensitive interferometer with closed-loop control of the reference mirror. A calibrated nanopositioner is used to lock the interferometer phase to the most sensitive point in the interfer- ogram. In this conguration, large low-frequency movements of the sensor mirror can be detected from the control signal applied to the nanopositioner and high-frequency short-range signals can be measured directly from the photodiode. It is demonstrated that these two signals are complementary and can be summed to find the total displacement. The resulting interferometer has a number of desirable characteristics: it is optically simple, does not require polarization or modulation to detect the direction of motion, does not require fringe-counting or interpolation electronics, and has a bandwidth equal to that of the photodiode. Experimental results demonstrate the frequency response analysis of a high-speed positioning stage. The proposed instru-

ment is ideal for measuring the frequency response of nanopositioners, electro-optical components, MEMs devices, Ultrasonic devices, and sensors such as surface acoustic wave detectors.},

keywords = {Nanopositioning, Optics, Sensors},

pubstate = {published},

tppubtype = {article}

}

@article{J15b,

title = {Simultaneous Optimization of Damping and Tracking Controller Parameters via Selective Pole Placement for Enhanced Positioning Bandwidth of Nanopositioners},

author = {D. Russell and A. J. Fleming and S. S. Aphale},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2015/07/DS-14-1539.pdf},

doi = {10.1115/1.4030723},

year  = {2015},

date = {2015-12-30},

journal = {Journal of Dynamic Systems, Measurement and Control},

volume = {137},

number = {10},

pages = {1-8},

abstract = {Positive Velocity and Position Feedback (PVPF) is a widely used control scheme in lightly damped resonant systems with collocated sensor actuator pairs. The popularity of PVPF is due to the ability to achieve a chosen damping ratio by repositioning the poles of the system. The addition of a tracking controller, to reduce the effects of inherent nonlinearities, causes the poles to deviate from the intended location and can be a detriment to the damping achieved. By designing the PVPF and tracking controllers simultaneously, the optimal damping and tracking can be achieved. Simulations show full damping of the first resonance mode and significantly higher bandwidth than that achieved using the traditional PVPF design method, allowing for high speed scanning with accurate tracking. Experimental results are also provided to verify performance in implementation.},

keywords = {Nanopositioning},

pubstate = {published},

tppubtype = {article}

}

@article{J15e,

title = {Low-order Damping and Tracking Control for Scanning Probe Systems},

author = {A. J. Fleming and Y. R. Teo and K. K. Leang

},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2015/12/J15e.pdf},

doi = {10.3389/fmech.2015.00014},

year  = {2015},

date = {2015-12-30},

journal = {Frontiers in Mechanical Engineering},

volume = {1},

pages = {1-9},

abstract = {This article describes an improvement to integral resonance damping control (IRC) for reference tracking applications such as Scanning Probe Microscopy and nanofabrication. It is demonstrated that IRC control introduces a low-frequency pole into the tracking loop which is detrimental for performance. In this work, the location of this pole is found analytically using Cardano’s method then compensated by parameterizing the tracking controller accordingly. This approach maximizes the closed-loop bandwidth whilst being robust to changes in the resonance frequencies. The refined IRC controller is comprehensively compared to other low-order methods in a practical environment.},

keywords = {Nanopositioning, SPM},

pubstate = {published},

tppubtype = {article}

}

@article{J15a,

title = {A New Electrical Configuration for Improving the Range of Piezoelectric Bimorph Benders},

author = {S. A. Rios and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2015/04/J15a3.pdf},

year  = {2015},

date = {2015-12-01},

journal = {Sensors and Actuators A: Physical},

volume = {224},

pages = {106-110},

abstract = {This article describes a new electrical configuration for driving piezoelectric benders. The ‘Biased Bipolar’ configuration is compatible with parallel-polled, bimorph and multimorph benders. The new configuration is similar to the standard three-wire drive method where the top electrode is biased with a DC voltage and the bottom electrode is grounded. However, the new configuration uses an alternate DC bias voltage and adjusted range for the central electrode which allows the full range of positive and negative electric fields to be utilized. Using this technique, the predicted deflection and force can be increased by a factor of 2.2 compared to the standard two wire configuration and 1.3 times for the standard three wire configuration. These predictions were verified experimentally where the measured factor of improvement in displacement and force was of 2.4 and 1.3 compared to the standard two-wire and three-wire configurations.},

keywords = {Piezoelectric Transducers and Drives},

pubstate = {published},

tppubtype = {article}

}

@article{J15c,

title = {Optimal integral force feedback for active vibration control},

author = {Y. R. Teo and A. J. Fleming},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2015/10/J15c.pdf},

year  = {2015},

date = {2015-06-27},

journal = {Journal of Sound and Vibration},

volume = {356},

number = {11},

pages = {20-33},

abstract = {This paper proposes an improvement to Integral Force Feedback (IFF), which is a popular method for active vibration control for structures and mechanical systems. Benefits of IFF includes robustness, guaranteed stability and simplicity. However, the maximum damping performance is dependent on the stiffness of the system; hence, some systems cannot be adequately controlled. In this paper, an improvement to the classical force feedback control scheme is proposed. The improved method achieves arbitrary damping for any mechanical system by introducing a feed-through term. The proposed improvement is experimentally demonstrated by actively damping an objective lens assembly for a high-speed confocal microscope.},

keywords = {Nanopositioning, Smart Structures},

pubstate = {published},

tppubtype = {article}

}

@article{J14b,

title = {Piezoelectric Actuators with Integrated High Voltage Power Electronics},

author = {A. J. Fleming and Y. K. Yong},

url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2015/10/J14b.pdf},

year  = {2015},

date = {2015-04-01},

journal = {IEEE/ASME Transactions on Mechatronics},

volume = {20},

number = {2},

pages = {611-617},

abstract = {This article explores the possibility of piezoelectric actuators with integrated high voltage power electronics. Such devices dramatically simplify the application of piezoelectric actuators since the power electronics are already optimized for the voltage range, capacitance, and power dissipation of the actuator. The foremost consideration is the thermal impedance of the actuator and heat dissipation. Analytical and finite-element methods are described for predicting the thermal impedance of a piezoelectric bender. The predictions are compared experimentally using thermal imaging on a piezoelectric bender with laminated miniature power electronics.},

keywords = {Piezoelectric Transducers and Drives},

pubstate = {published},

tppubtype = {article}

}