@article{MRL_AFM_Low_cost_AFM,

title = {A modular low-cost atomic force microscope for precision mechatronics education},

author = {Fangzhou Xia and James Quigley and Xiaotong Zhang and Chen Yang and Yi Wang and Kamal Youcef-Toumi},

url = {https://www.sciencedirect.com/science/article/pii/S0957415821000441},

doi = {https://doi.org/10.1016/j.mechatronics.2021.102550},

issn = {0957-4158},

year  = {2021},

date = {2021-04-15},

journal = {Mechatronics},

volume = {76},

pages = {102550},

publisher = {ScienceDirect},

abstract = {Precision mechatronics and nanotechnology communities can both benefit from a course centered around an Atomic Force Microscope (AFM). Developing an AFM can provide precision mechatronics engineers with a valuable multidisciplinary hands-on training experience. In return, such expertise can be applied to the design and implementation of new precision instruments, which helps nanotechnology researchers make new scientific discoveries. However, existing AFMs are not suitable for mechatronics education due to their different original design intentions. Therefore, we address this challenge by developing an AFM intended for precision mechatronics education. This paper presents the design and implementation of an educational AFM and its corresponding precision mechatronics class. The modular educational AFM is low-cost (≤$4,000) and easy to operate. The cost reduction is enabled by new subsystem development of a buzzer-actuated scanner and demodulation electronics designed to interface with a myRIO data acquisition system. Moreover, the use of an active cantilever probe with piezoresistive sensing and thermomechanical actuation significantly reduced experiment setup overhead with improved operational safety. In the end, the developed AFM capabilities are demonstrated with imaging results. The paper also showcases the course design centered around selected subsystems. The new AFM design allows scientific-method-based learning, maximizes utilization of existing resources, and offers potential subsystem upgrades for high-end research applications. The presented instrument and course can help connect members of both the AFM and the mechatronics communities to further develop advanced techniques for new applications.},

keywords = {Experimentation, Fabrication, Instrumentation, Mechatronic Design, Nanoscale video imaging for dynamic process visualization, Nanotechnology, Physical System Modeling},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Charge_Controller_PBFODC,

title = {Modeling and Control of Piezoelectric Hysteresis: A Polynomial-Based Fractional Order Disturbance Compensation Approach},

author = {Chen Yang and Nicolas Verbeek and Fangzhou Xia and Yi Wang and Kamal Youcef-Toumi},

url = {https://ieeexplore.ieee.org/document/9027124},

doi = {10.1109/TIE.2020.2977567},

issn = {1557-9948},

year  = {2020},

date = {2020-03-06},

journal = {IEEE Transactions on Industrial Electronics},

publisher = {IEEE},

abstract = {Piezoelectric hysteresis is a critical issue that significantly degrades the motion accuracy of piezo-actuated nanopositioners. Such an issue is difficult to be precisely modeled and compensated for, primarily due to its asymmetric, rate and input amplitude dependent characteristics. This paper proposes a novel method to deal with this challenge. Specifically, a polynomial-based fractional order disturbance model is proposed to accommodate and characterize the complex hysteresis effect. In this model, the rate dependency is captured by a general method of implementing curve fitting in Bode magnitude plot. The inverse model for control purposes is immediately available from the original one. The proposed method does not require expensive computational resources. In fact, this paper shows that this controller can be easily implemented in an analog manner, which brings the advantages of high-bandwidth and low-cost. Extensive modeling and tracking experiments are carried out to demonstrate the effectiveness of the proposed method. It is shown that the piezoelectric hysteresis nonlinearity can be significantly suppressed over a wide bandwidth.},

keywords = {Control Theory, Experimentation, Nanoscale video imaging for dynamic process visualization, Nanotechnology, Physical System Modeling, Simulation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Quadrature_Monte_Carlo,

title = {Why simple quadrature is just as good as Monte Carlo},

author = {Kevin Vanslette and Abdullatif Al Alsheikh and Kamal Youcef-Toumi},

url = {http://dx.doi.org/10.1515/mcma-2020-2055},

doi = {10.1515/mcma-2020-2055},

issn = {1569-3961},

year  = {2020},

date = {2020-03-01},

journal = {Monte Carlo Methods and Applications},

volume = {26},

number = {1},

pages = {1–16},

publisher = {Walter de Gruyter GmbH},

abstract = {We motive and calculate Newton–Cotes quadrature integration variance and compare it directly with Monte Carlo (MC) integration variance. We find an equivalence between deterministic quadrature sampling and random MC sampling by noting that MC random sampling is statistically indistinguishable from a method that uses deterministic sampling on a randomly shuffled (permuted) function. We use this statistical equivalence to regularize the form of permissible Bayesian quadrature integration priors such that they are guaranteed to be objectively comparable with MC. This leads to the proof that simple quadrature methods have expected variances that are less than or equal to their corresponding theoretical MC integration variances. Separately, using Bayesian probability theory, we find that the theoretical standard deviations of the unbiased errors of simple Newton–Cotes composite quadrature integrations improve over their worst case errors by an extra dimension independent factor ∝ N−1/2 This dimension independent factor is validated in our simulations.},

keywords = {Computational Intelligence, Control Theory, Experimentation, intelligent systems, Modeling; sizing and control for smart grids, Simulation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_Model_Validation_Testing,

title = {A general model validation and testing tool},

author = {Kevin Vanslette and Tony Tohme and Kamal Youcef-Toumi},

url = {https://www.sciencedirect.com/science/article/pii/S0951832019302571},

doi = {https://doi.org/10.1016/j.ress.2019.106684},

issn = {0951-8320},

year  = {2019},

date = {2019-10-28},

journal = {Reliability Engineering & System Safety},

volume = {195},

pages = {106684},

publisher = {Elsevier BV},

abstract = {We construct and propose the “Bayesian Validation Metric” (BVM) as a general model validation and testing tool. We find the BVM to be capable of representing all of the standard validation metrics (square error, reliability, probability of agreement, frequentist, area, probability density comparison, statistical hypothesis testing, and Bayesian model testing) as special cases and find that it can be used to improve, generalize, or further quantify their uncertainties. Thus, the BVM allows us to assess the similarities and differences between existing validation metrics in a new light. The BVM has the capacity to allow users to invent and select models according to novel validation requirements. We formulate and test a few novel compound validation metrics that improve upon other validation metrics in the literature. Further, we construct the BVM Ratio for the purpose of quantifying model selection under user defined definitions of agreement in the presence or absence of uncertainty. This construction generalizes the Bayesian model testing framework.},

keywords = {Algorithms, Computational Intelligence, Control Theory, Experimentation, intelligent systems, Probabilistic neural networks for robust machine learning, Simulation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_coated_probe,

title = {Lights Out! Nano-Scale Topography Imaging of Sample Surface in Opaque Liquid Environments with Coated Active Cantilever Probes},

author = {Fangzhou Xia and Chen Yang and Yi Wang and Kamal Youcef-Toumi and Christoph Reuter and Tzvetan Ivanov and Mathias Holz and Ivo W Rangelow},

url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6669515/},

doi = {10.3390/nano9071013},

year  = {2019},

date = {2019-07-09},

journal = {Nanomaterials},

volume = {9},

number = {7},

pages = {1013},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Atomic force microscopy is a powerful topography imaging method used widely in nanoscale metrology and manipulation. A conventional Atomic Force Microscope (AFM) utilizes an optical lever system typically composed of a laser source, lenses and a four quadrant photodetector to amplify and measure the deflection of the cantilever probe. This optical method for deflection sensing limits the capability of AFM to obtaining images in transparent environments only. In addition, tapping mode imaging in liquid environments with transparent sample chamber can be difficult for laser-probe alignment due to multiple different refraction indices of materials. Spurious structure resonance can be excited from piezo actuator excitation. Photothermal actuation resolves the resonance confusion but makes optical setup more complicated. In this paper, we present the design and fabrication method of coated active scanning probes with piezoresistive deflection sensing, thermomechanical actuation and thin photoresist polymer surface coating. The newly developed probes are capable of conducting topography imaging in opaque liquids without the need of an optical system. The selected coating can withstand harsh chemical environments with high acidity (e.g., 35% sulfuric acid). The probes are operated in various opaque liquid environments with a custom designed AFM system to demonstrate the imaging performance. The development of coated active probes opens up possibilities for observing samples in their native environments.},

keywords = {Experimentation, Fabrication, Full text available online, Instrumentation, Mechatronic Design, Nanoscale video imaging for dynamic process visualization, Nanotechnology, Physical System Modeling, Visualization},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Vectorized_Uncertainty_Input_Probability,

title = {Vectorized Uncertainty Propagation and Input Probability Sensitivity Analysis},

author = {Kevin Vanslette and Arwa Alanqari and Zeyad Al-awwad and Kamal Youcef-Toumi},

url = {https://arxiv.org/abs/1908.11246},

doi = {1908.11246v1},

year  = {2019},

date = {2019-06-04},

publisher = {King Abdulaziz City for Science and Technology},

abstract = {In this article we construct a theoretical and computational process for assessing Input Probability Sensitivity Analysis (IPSA) using a Graphics Processing Unit (GPU) enabled technique called Vectorized Uncertainty 

Propagation (VUP). VUP propagates probability distributions through 

a parametric computational model in a way that’s computational time 

complexity grows sublinearly in the number of distinct propagated input probability distributions. VUP can therefore be used to efficiently 

implement IPSA, which estimates a model’s probabilistic sensitivity to 

measurement and parametric uncertainty over each relevant measurement 

location. Theory and simulation illustrate the effectiveness of these methods.},

keywords = {Algorithms, Computational Intelligence, Experimentation, Uncertainty estimation and calibration for modeling},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Charge_Controller_Self_Compensating,

title = {Charge Controller With Decoupled and Self-Compensating Configurations for Linear Operation of Piezoelectric Actuators in a Wide Bandwidth},

author = {Chen Yang and Changle Li and Fangzhou Xia and Yanhe Zhu and Jie Zhao and Kamal Youcef-Toumi},

url = {https://ieeexplore.ieee.org/document/8466119},

doi = {10.1109/TIE.2018.2868321},

year  = {2018},

date = {2018-09-14},

journal = {IEEE Transactions on Industrial Electronics},

volume = {66},

number = {7},

pages = {5392--5402},

publisher = {IEEE},

abstract = {Charge control is a well-known sensorless approach to operate piezoelectric actuators, which has been proposed for more than 30 years. However, it is rarely used in industry because the implemented controllers suffer from the issues of limited low-frequency performance, long settling time, floating-load, and loss of stroke, etc. In this paper, a novel controller circuit dedicated to overcome these issues is presented. In the proposed scheme, a grounded-load charge controller with decoupled configuration is developed, which separates high-frequency and low-frequency paths, thus achieving arbitrarily low transition frequency without increasing the settling time. Based on this, a self-compensating configuration is further proposed and integrated into the controller circuit, which makes full use of controller output to improve its own control performance at low frequencies. Experimental results show that the presented charge controller can effectively reduce more than 88% of the hysteretic nonlinearity even when operating close to the transition frequency. To demonstrate its practical value, we then integrate it into a custom-designed high-speed atomic force microscope system. By comparing images obtained from using voltage drive and charge controller, it is clear that the piezoelectric hysteresis has been significantly reduced in a wide bandwidth.},

keywords = {Control Theory, Experimentation, Instrumentation, Nanoscale video imaging for dynamic process visualization, Nanotechnology, Physical System Modeling, Simulation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Comparison_Industrial_Social_Welfare,

title = {Demand side management in power grid enterprise control: A comparison of industrial & social welfare approaches},

author = {Bo Jiang and Aramazd Muzhikyan and Amro M Farid and Kamal Youcef-Toumi},

url = {https://www.sciencedirect.com/science/article/pii/S0306261916315410},

doi = {https://doi.org/10.1016/j.apenergy.2016.10.096},

issn = {0306-2619},

year  = {2016},

date = {2016-10-25},

journal = {Applied Energy},

volume = {187},

pages = {833-846},

publisher = {ScienceDirect},

abstract = {Despite the recognized importance of demand side management (DSM) for mitigating the impact of variable energy resources and reducing the system costs, the academic and industrial literature have taken divergent approaches to DSM implementation. The prequel to this paper has demonstrated that the netload baseline inflation – a feature particular to the industrial DSM unit commitment formulation – leads to higher and costlier day-ahead scheduling compared to the academic social welfare method. This paper now expands this analysis from a single optimization problem to the full power grid enterprise control with its multiple control layers at their associated time scales. These include unit commitment, economic dispatch and regulation services. It compares the two DSM formulations and quantifies the technical and economic impacts of industrial baseline errors in the day-ahead and real-time markets. The paper concludes that the presence of baseline errors – present only in the industrial model – leads to a cascade of additional system imbalances and costs as compared to the social welfare model. A baseline error introduced in the unit commitment problem will increase costs not just in the day-ahead market, but will also introduce a greater netload error residual in the real-time market causing additional cost and imbalances. These imbalances if left unmitigated degrade system reliability or otherwise require costly regulating reserves to achieve the same performance. An additional baseline error introduced in the economic dispatch further compounds this cascading effect with additional costs in the real-time market, amplified downstream imbalances, and further regulation capacity for its mitigation.},

keywords = {Algorithms, Control Theory, Experimentation, Robot operated modular fixtures, Robotics & Automation, Simulation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_LRHS_imaging,

title = {Design and control of multi-actuated atomic force microscope for large-range and high-speed imaging},

author = {Iman Soltani Bozchalooi and Andrew Careaga Houck and Jwaher M. AlGhamdi and Kamal Youcef-Toumi},

url = {http://www.sciencedirect.com/science/article/pii/S0304399115300528 https://www.youtube.com/watch?v=PQ-zE6wA61c},

doi = {https://doi.org/10.1016/j.ultramic.2015.10.016},

issn = {0304-3991},

year  = {2016},

date = {2016-01-01},

volume = {160},

pages = {213 - 224},

abstract = {This paper presents the design and control of a high-speed and large-range atomic force microscopy (AFM). A multi-actuation scheme is proposed where several nano-positioners cooperate to achieve the range and speed requirements. A simple data-based control design methodology is presented to effectively operate the AFM scanner components. The proposed controllers compensate for the coupled dynamics and divide the positioning responsibilities between the scanner components. As a result, the multi-actuated scanner behavior is equivalent to that of a single X–Y–Z positioner with large range and high speed. The scanner of the designed AFM is composed of five nano-positioners, features 6μm out-of-plane and 120μm lateral ranges and is capable of high-speed operation. The presented AFM has a modular design with laser spot size of 3.5μm suitable for small cantilever, an optical view of the sample and probe, a conveniently large waterproof sample stage and a 20MHz data throughput for high resolution image acquisition at high imaging speeds. This AFM is used to visualize etching of calcite in a solution of sulfuric acid. Layer-by-layer dissolution and pit formation along the crystalline lines in a low pH environment is observed in real time.},

keywords = {Control Theory, Experimentation, Fabrication, Instrumentation, Mechatronic Design, Nanoscale video imaging for dynamic process visualization, Nanotechnology, Simulation, Visualization},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Holistic_Assessment_Electricity_Grid,

title = {The need for holistic enterprise control assessment methods for the future electricity grid},

author = {Amro M Farid and Bo Jiang and Aramazd Muzhikyan and Kamal Youcef-Toumi},

url = {https://www.sciencedirect.com/science/article/pii/S1364032115012599},

doi = {https://doi.org/10.1016/j.rser.2015.11.007},

issn = {1364-0321},

year  = {2015},

date = {2015-12-17},

journal = {Renewable and Sustainable Energy Reviews},

volume = {56},

pages = {669-685},

publisher = {elsevier},

abstract = {Recently, the academic and industrial literature has coalesced around an enhanced vision of the electric power grid that is responsive, dynamic, adaptive and flexible. As driven by decarbonization, reliability, transportation electrification, consumer participation and deregulation, this future grid will undergo technical, economic and regulatory changes to bring about the incorporation of renewable energy and incentivized demand side management and control. As a result, the power grid will experience fundamental changes in its physical system structure and behavior that will consequently require enhanced and integrated control, automation, and IT-driven management functions in what is called enterprise control. While these requirements will open a plethora of opportunities for new control technologies, many of these solutions are largely overlapping in function. Their overall contribution to holistic techno-economic control objectives and their underlying dynamic properties are less than clear. Piece-meal integration and a lack of coordinated assessment could bring about costly-overbuilt solutions or even worse unintended reliability consequences. This work, thus, reviews these existing trends in the power grid evolution. It then motivates the need for holistic methods of integrated assessment that manage the diversity of control solutions against their many competing objectives and contrasts these requirements to existing variable energy resource integration studies. The work concludes with a holistic framework for “enterprise control” assessment of the future power grid and suggests directions for future work.},

keywords = {Algorithms, Control Theory, Experimentation, intelligent systems, Modeling; sizing and control for smart grids, Physical System Modeling, Simulation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Agreecan_Nanoscale_Solid,

title = {Aggrecan Nanoscale Solid–Fluid Interactions Are a Primary Determinant of Cartilage Dynamic Mechanical Properties},

author = {Hadi Nia and Lin Han and Iman Soltani and Peter Roughley and Kamal Youcef-Toumi and Alan Grodzinsky and Christine Ortiz},

doi = {10.1021/nn5062707},

issn = {2614-2625},

year  = {2015},

date = {2015-03-10},

journal = {ACS nano},

volume = {9},

publisher = {ACS},

abstract = {Poroelastic interactions between interstitial fluid and the extracellular 

matrix of connective tissues are critical to biological and pathophysiological functions 

involving solute transport, energy dissipation, self-stiffening and lubrication. However, 

the molecular origins of poroelasticity at the nanoscale are largely unknown. Here, the 

broad-spectrum dynamic nanomechanical behavior of cartilage aggrecan monolayer is 

revealed for the first time, including the equilibrium and instantaneous moduli and the 

peak in the phase angle of the complex modulus. By performing a length scale study 

and comparing the experimental results to theoretical predictions, we confirm that the 

mechanism underlying the observed dynamic nanomechanics is due to solid
fluid 

interactions (poroelasticity) at the molecular scale. Utilizing finite element modeling, the molecular-scale hydraulic permeability of the aggrecan assembly was quantified (kaggrecan = (4.8 ( 2.8) 10
15 m4 

/N 3 s) and found to be similar to the nanoscale hydraulic permeability of intact normal cartilage tissue 

but much lower than that of early diseased tissue. The mechanisms underlying aggrecan poroelasticity were further investigated by altering electrostatic 

interactions between the molecule's constituent glycosaminoglycan chains: electrostatic interactions dominated steric interactions in governing molecular 

behavior. While the hydraulic permeability of aggrecan layers does not change across species and age, aggrecan from adult human cartilage is stiffer than 

the aggrecan from newborn human tissue.},

keywords = {Experimentation, Fabrication, Nanoscale video imaging for dynamic process visualization, Nanotechnology, Physical System Modeling},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Noise_Control_Decoupling,

title = {Noise and control decoupling of Advanced LIGO suspensions},

author = {B N Shapiro and R Adhikari and J Driggers and J Kissel and B Lantz and J Rollins and K Youcef-Toumi},

url = {https://doi.org/10.1088/0264-9381/32/1/015004},

doi = {10.1088/0264-9381/32/1/015004},

year  = {2014},

date = {2014-12-10},

journal = {Classical and Quantum Gravity},

volume = {32},

number = {1},

pages = {015004},

publisher = {IOP Publishing},

abstract = {Ground-based interferometric gravitational wave observatories such as Advanced LIGO must isolate their optics from ground vibrations with suspension systems to meet their stringent noise requirements. These suspensions typically have very high quality-factor resonances that require active damping. The sensor noise associated with this damping is a potential significant contributor to the sensitivity of these interferometers. This paper introduces a novel scheme for suspension damping that isolates much of this noise and permits greater amounts of damping. It also decouples the damping feedback design from the interferometer control. The scheme works by invoking a change from a local coordinate frame associated with each suspension, to a coordinate frame aligned with the interferometric readout. In this way, degrees of freedom invisible to the readout can employ effective, but noisy damping. The degree of freedom measured by the readout is then damped using low noise interferometer signals, eliminating the need to use the usual noisy sensors. Simulated and experimental results validate the concepts presented in this paper.},

keywords = {Control Theory, Experimentation, intelligent systems, Physical System Modeling, Simulation, Uncertainty estimation and calibration for modeling, Visualization},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_State_Estimation_Power,

title = {Event triggered state estimation techniques for power systems with integrated variable energy resources},

author = {Reshma C Francy and Amro M Farid and Kamal Youcef-Toumi},

url = {https://doi.org/10.1016/j.isatra.2014.11.001},

doi = {10.1016/j.isatra.2014.11.001},

issn = {0019-0578},

year  = {2014},

date = {2014-11-24},

journal = {ISA transactions},

volume = {56},

pages = {165—172},

abstract = {For many decades, state estimation (SE) has been a critical technology for energy management systems utilized by power system operators. Over time, it has become a mature technology that provides an accurate representation of system state under fairly stable and well understood system operation. The integration of variable energy resources (VERs) such as wind and solar generation, however, introduces new fast frequency dynamics and uncertainties into the system. Furthermore, such renewable energy is often integrated into the distribution system thus requiring real-time monitoring all the way to the periphery of the power grid topology and not just the (central) transmission system. The conventional solution is two fold: solve the SE problem (1) at a faster rate in accordance with the newly added VER dynamics and (2) for the entire power grid topology including the transmission and distribution systems. Such an approach results in exponentially growing problem sets which need to be solver at faster rates. This work seeks to address these two simultaneous requirements and builds upon two recent SE methods which incorporate event-triggering such that the state estimator is only called in the case of considerable novelty in the evolution of the system state. The first method incorporates only event-triggering while the second adds the concept of tracking. Both SE methods are demonstrated on the standard IEEE 14-bus system and the results are observed for a specific bus for two difference scenarios: (1) a spike in the wind power injection and (2) ramp events with higher variability. Relative to traditional state estimation, the numerical case studies showed that the proposed methods can result in computational time reductions of 90. These results were supported by a theoretical discussion of the computational complexity of three SE techniques. The work concludes that the proposed SE techniques demonstrate practical improvements to the computational complexity of classical state estimation. In such a way, state estimation can continue to support the necessary control actions to mitigate the imbalances resulting from the uncertainties in renewables.},

keywords = {Control Theory, Experimentation, intelligent systems, Modeling; sizing and control for smart grids, Physical System Modeling, Simulation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Leak_Detector,

title = {Design of a Novel In-Pipe Reliable Leak Detector},

author = {D Chatzigeorgiou and K Youcef-Toumi and R Ben-Mansour},

url = {https://ieeexplore.ieee.org/document/6778062?arnumber=6778062},

doi = {10.1109/TMECH.2014.2308145},

issn = {1941-014X},

year  = {2014},

date = {2014-03-25},

journal = {IEEE/ASME Transactions on Mechatronics},

volume = {20},

number = {2},

pages = {824-833},

publisher = {IEEE},

abstract = {Leakage is the major factor for unaccounted losses in every pipe network around the world (oil, gas, or water). In most cases, the deleterious effects associated with the occurrence of leaks may present serious economical and health problems. Therefore, leaks must be quickly detected, located, and repaired. Unfortunately, most state-of-the-art leak detection systems have limited applicability, are neither reliable nor robust, while others depend on the user experience. In this paper, we present a new in-pipe leak detection system. It performs autonomous leak detection in pipes and, thus, eliminates the need for the user experience. This paper focuses on the detection module and its main characteristics. Detection in based on the presence of a pressure gradient in the neighborhood of the leak. Moreover, the proposed detector can sense leaks at any angle around the circumference of the pipe with only two sensors. We validate the concepts by building a prototype and evaluate the system's performance under real conditions in an experimental laboratory setup.},

keywords = {Control Theory, Experimentation, Inspection, Physical System Modeling, repair & intelligence for water distribution pipes, Robotics & Automation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Multi_PI_control,

title = {Multi-actuation and PI control: A simple recipe for high-speed and large-range atomic force microscopy},

author = {Iman Soltani Bozchalooi and Kamal Youcef-Toumi},

url = {http://www.sciencedirect.com/science/article/pii/S0304399114001491},

doi = {https://doi.org/10.1016/j.ultramic.2014.07.010},

issn = {0304-3991},

year  = {2014},

date = {2014-01-01},

journal = {Ültramicroscopy},

volume = {146},

pages = {117 - 124},

abstract = {High speed atomic force microscopy enables observation of dynamic nano-scale processes. However, maintaining a minimal interaction force between the sample and the probe is challenging at high speed specially when using conventional piezo-tubes. While rigid AFM scanners are operational at high speeds with the drawback of reduced tracking range, multi-actuation schemes have shown potential for high-speed and large-range imaging. Here we present a method to seamlessly incorporate additional actuators into conventional AFMs. The equivalent behavior of the resulting multi-actuated setup resembles that of a single high-speed and large-range actuator with maximally flat frequency response. To achieve this, the dynamics of the individual actuators and their couplings are treated through a simple control scheme. Upon the implementation of the proposed technique, commonly used PI controllers are able to meet the requirements of high-speed imaging. This forms an ideal platform for retroactive enhancement of existing AFMs with minimal cost and without compromise on the tracking range. A conventional AFM with tube scanner is retroactively enhanced through the proposed method and shows an order of magnitude improvement in closed loop bandwidth performance while maintaining large range. The effectiveness of the method is demonstrated on various types of samples imaged in contact and tapping modes, in air and in liquid.},

keywords = {Control Theory, Experimentation, Instrumentation, Nanoscale video imaging for dynamic process visualization, Nanotechnology, Physical System Modeling, Simulation},

pubstate = {published},

tppubtype = {article}

}

@article{MRL_AFM_Distance_Decaying_Sensors,

title = {Optimal coverage of an infrastructure network using sensors with distance-decaying sensing quality},

author = {Ajay Deshpande and Sanjay E Sarma and Kamal Youcef-Toumi and Samir Mekid},

url = {https://www.sciencedirect.com/science/article/pii/S0005109813003774},

doi = {https://doi.org/10.1016/j.automatica.2013.07.029},

issn = {0005-1098},

year  = {2013},

date = {2013-08-27},

journal = {Automatica},

volume = {49},

number = {11},

pages = {3351-3358},

publisher = {elsevier},

abstract = {Motivated by recent applications of wireless sensor networks in monitoring infrastructure networks, we address the problem of optimal coverage of infrastructure networks using sensors whose sensing performance decays with distance. We show that this problem can be formulated as a continuous p-median problem on networks. The literature has addressed the discrete p-median problem on networks and in continuum domains, and the continuous p-median problem in continuum domains extensively. However, in-depth analysis of the continuous p-median problem on networks has been lacking. With the sensing performance model that decays with distance, each sensor covers a region equivalent to its Voronoi partition on the network in terms of the shortest path distance metric. Using Voronoi partitions, we define a directional partial derivative of the coverage metric with respect to a sensor’s location. We then propose a gradient descent algorithm to obtain a locally optimal solution with guaranteed convergence. The quality of an optimal solution depends on the choice of the initial configuration of sensors. We obtain an initial configuration using two approaches: by solving the discrete p-median problem on a lumped network and by random sampling. We consider two methods of random sampling: uniform sampling and D2-sampling. The first approach with the initial solution of the discrete p-median problem leads to the best coverage performance for large networks, but at the cost of high running time. We also observe that the gradient descent on the initial solution with the D2-sampling method yields a solution that is within at most 7% of the previous solution and with much shorter running time.},

keywords = {Experimentation, Fabrication, Instrumentation, Mechatronic Design, Modeling; sizing and control of smart grids, Physical System Modeling},

pubstate = {published},

tppubtype = {article}

}