Magnetic Motion Research Articles

Fuzzy Neural Network Control for a Reaction Force Compensation Linear Motor Motion Stage

Technological progress and market expansion in the semiconductor industry require ultra-precise and high-speed processing and motion systems. However, even though reaction force compensation (RFC) linear motor motion stages help reduce the transmitted reaction force, the residual vibration of the movable magnet track after motion acts as a disturbance, affecting settling time and tracking performance. To address this issue, this study introduces a fuzzy neural network controller for an RFC linear motor motion stage. Since non-linear factors, such as frictional forces from guide rails, make it difficult to accurately model the system, a Nonlinear Autoregressive Neural Network (NARX) is used to identify the nonlinearity from displacement and servo control outputs. The fuzzy logic controller, which takes into account the error and error rate, is then combined with the inverse model controller of NARX. Finally, the fuzzy neural network controllers are integrated with the existing PIV (proportional-integral-velocity) control in feedforward configurations. The experiments demonstrate the potential performance improvements of the proposed approach over the PIV controllers.

Determination of the acceleration due to gravity by studying magnet's motion through a conducting pipe

Determination of the acceleration due to gravity by studying magnet's motion through a conducting pipe

A neural network inverse problem solution for a MIMO magnetic levitation actuator

A multiple-input and multiple-output planar actuator is proposed, which utilizes mechanically driven stator magnet arrays to levitate a permanent magnet mover. A state of levitation and actuation is obtained by mechanically altering the orientation of the stator magnets to control the forces and torques on the mover. A challenge for the design and control of the actuator is inverting the relationship between the force and stator magnet rotation angles, as there is no closed-form analytical solution. In this study, a feed-forward neural network is applied to model the forward relation between stator magnet angle input and a force and torque output to reduce the forward computation time for the design process and for error estimation in real-time applications. Additionally, the neural network is considered for inverting the solution for a motion profile sampled at 1000 Hz. The developed forward model is able to calculate the forces and torques on the mover a factor 10 faster than the equivalent charge or Fourier model with an absolute error of 3 mN and 0.1 mNm for the forces and torques, respectively, and a feed-forward neural network is able to accurately learn an inverse solution for small motion profiles.

Piezoelectric breeze energy harvester with mechanical intelligence mechanism for smart agricultural monitoring systems

In this paper, a piezoelectric breeze energy harvester with a mechanical intelligence mechanism for smart agricultural monitoring systems (G-PBEH) is proposed. Different from the conventional magnetically coupled piezoelectric cantilever beam harvesters where the end magnet is mostly fixed, the G-PBEH has movable magnets in a fixed cylindrical channel. Which could achieve a mechanical intelligence mechanism with the tuned magnets on the shell, contributing to increasing voltage frequency and widening wind bandwidth. The effects of cylindrical channel length (L) and tuned magnet diameter (D) on performance were investigated. The experimental findings reveal that when L is 10 mm and D is 8 mm, the prototype starts at 2 m s−1, and the highest voltage and power are 17.9 V and 944.07 μW (150 kΩ) at 8 m s−1 . Compared to L is 5 mm (magnet fixed), the voltage waveform has a 28.6% increase in the quantity of peaks. Besides, the voltage is larger than 3 V occupying 91.6% of the experimental wind bandwidth. The application experiment demonstrates that the G-PBEH can be used as a reliable power supplier, which can facilitate the progress of smart monitoring systems for simplified greenhouses in remote areas.

Modified free energy generation using permanent Neodymium Magnet based on Bedini with Maxwell and Lorenz gauge conditions

An efficient, reliable, and real-time electricity generator is proposed by keeping in view the constraints, related to the electricity generation cost, resource reservoirs, greenhouse gas emission, energy storage, and power demand for a pre-defined residential area. Paramount importance is given to the rotor's design; coupled with movable neodymium magnets to increase the harvester's life span and system's net revenue. For the amplification in the stator output, a cost-effective approach is adopted that is based on the parallel winding of the bifilar coil. Furthermore, the coefficient of performance factor for the Bedini's smart school girl circuit based electricity harvester is modified by aiding the concepts of radiant energy incorporated with the electromagnetic phenomenon. Moreover, the mathematical model is formulated by the Maxwell equations using the Lorenz gauge condition to capture free vacuum energy from the environment. For the investigation, analysis, and corroboration of the proposed design, results are reported after performing extensive numerical computations and a comprehensive comparison between the original and modified design is stated in detail.

Comparative Analysis of Force and Eddy Current Position Sensing Approaches for a Magnetic Levitation Platform with an Exceptional Hovering Distance

This paper provides a comparative analysis between a force sensor and an eddy current sensor, focusing on their usability to determine the position of a circular levitating permanent magnet (PM) mover within an axially symmetric magnetic levitation platform (MLP) with an exceptionally large air gap. The sensors enable closed-loop control, which is essential for accurately and stably maintaining the mover’s radial position. For the considered MLP, a change in radial position in principle results in a tilting of the mover, i.e., a deviation from the parallel alignment relative to the stator. As both the radial position and the tilting angle affect the sensors’ (force and eddy current) output voltage, an observer must deduce the radial position from the output sensor’s voltage, requiring a comprehensive MLP dynamic model and calibration of the models for both sensing approaches. The paper discusses the advantages and weaknesses of each sensor concept, exploring operational principles and performance in levitation tests. The force sensor exhibits versatility, proving functional across various application scenarios, such as when the mover is sealed in a conductive, non-magnetic chamber. In contrast, due to its high-frequency operation, the eddy current sensor is more straightforward to characterize, simplifying its behavior relative to the mover’s slower dynamics. Measurements are conducted to validate the models, showing the eddy current sensor’s robustness against disturbances and imperfections in the MLPs and its immunity to cross-axis interference. Conclusively, in levitation experiments where the mover is vertically distanced at 104 mm from the stator, the eddy current sensor achieves a position tracking precision about ten times better and a signal-to-noise ratio (SNR) ten times higher compared to the off-the-shelf force sensor, confirming its better performance and reliability; however, it cannot be used in applications where conductive objects are present in the air gap. Furthermore, additional experiments are conducted on the MLP using the eddy current sensor to show the controller’s robustness and dynamic reference tracking capability, with and without a payload.

Research on a rotary piezoelectric energy harvester based on movable magnets

A hybrid energy harvester (HEH) is designed using a movable magnet to harvest the mechanical energy for rotational motion. One movement of the movable magnet can generate electricity from piezoelectric nanogenerators (PENG) and electromagnetic generators (EMG), improving the energy conversion efficiency of HEH. The main factors affecting the motion characteristics of active magnets (number of magnets and magnet diameter) are illustrated through theoretical modeling and simulation, and the voltage characteristics of EMG and vibration characteristics of PENG are analyzed. According to the main factors affecting the motion characteristics, the experimental testing system was set up. The results show that the voltage of PENG and EMG can be up to 6.55 V and 1.37 V, respectively as the magnet diameter is 10 mm and the number of magnets is 5. The maximum power of PENG is 2.4 mW at 30 kΩ, and the power of EMG is 0.49 mW at 4 kΩ. The application experiment also proves the feasibility of the practical application of R-PEH, which provides a new solution for the research of hybrid energy harvesting systems.

Fully Integrated Microfluidic Device for Magnetic Bead Manipulation to Assist Rapid Reaction and Cleaning.

Methods to manipulate magnetic beads are essential factors to determine the efficiency and dimension of an in vitro diagnostic system. Currently, using movable permanent magnets and planar electromagnets is still the major approach to achieve magnetic bead control, causing significant constraint in the miniaturization of in vitro diagnostic systems. Here, we propose techniques to construct a fully integrated microfluidic device that can conduct automatic magnetic bead manipulation as well as rapid chemical reaction and cleaning in a minimized dimension similar to a USB disk. The device combines the precision control of multiple electromagnetic coils with the compactness of microfluidic channels, leading to one of the smallest automatic magnetic bead manipulation systems that can complete several major magnetic bead-based operation steps such as sample injection, reaction, cleaning, and collection. The influencing factors such as coil driving parameters, surface treatment of the microchannels, and properties of magnetic particles have also been investigated to optimize the device performance. The device can drive mixtures of Fe3O4 microparticles and polymer magnetic beads (PMBs) with a weight ratio of 1:1 at a maximum speed of 0.5 cm·s-1 and reduce the time for DNA binding and dissociation reactions from 20 min to only 48 s. This device has significantly advanced the conventional manipulation methods of magnetic beads and has demonstrated the possibility to construct an automatic and ultraminiaturized in vitro diagnostic system that may facilitate portable or even wearable chemical analysis.

Computational Analysis of Semi-Analytical Modeling Techniques for a Novel PM-Based Planar Actuator

A novel type of permanent magnet planar actuator is proposed which consists of a permanent magnet mover that interacts with individually mechanically controllable permanent magnets in the stator. A state of levitation and actuation is obtained by mechanically altering the orientation of the stator magnets to control the forces and torques on the mover. To design and control the actuator, fast and accurate electromagnetic models are required. In this study, the harmonic modeling technique is applied to rotating and translating cuboidal and cylindrical permanent magnets and is compared to the equivalent charge model in terms of accuracy and computational effort. The models are compared for a finite stator topology which demonstrates that the harmonic model has a substantial computational advantage over the equivalent charge method in a non-periodic system while both models are in good agreement in terms of accuracy.

Versatile magnetic configuration for the control and manipulation of superparamagnetic nanoparticles

The control and manipulation of superparamagnetic nanoparticles (SP-MNP) is a significant challenge and has become increasingly important in various fields, especially in biomedical research. Yet, most of applications rely on relatively large nanoparticles, 50 nm or higher, mainly due to the fact that the magnetic control of smaller MNPs is often hampered by the thermally induced Brownian motion. Here we present a magnetic device able to manipulate remotely in microfluidic environment SP-MNPs smaller than 10 nm. The device is based on a specifically tailored configuration of movable permanent magnets. The experiments performed in 500 µm capillary have shown the ability to concentrate the SP-MNPs into regions characterized by different shapes and sizes ranging from 100 to 200 µm. The results are explained by straightforward calculations and comparison between magnetic and thermal energies. We provide then a comprehensive description of the magnetic field intensity and its spatial distribution for the confinement and motion of magnetic nanoparticles for a wide range of sizes. We believe this description could be used to establish accurate and quantitative magnetic protocols not only for biomedical applications, but also for environment, food, security, and other areas.

Design of a Compact Planar Magnetic Levitation System with Wrench–Current Decoupling Enhancement

Magnetic levitation technology has promising applications in modern manufacturing, especially for fine-motion stage and long-range omnidirectional planar motors. This paper presents the development of a compact planar maglev prototype with the potential to achieve both applications to increase flexibility for the manufacturing system. The planar stator is designed by using optimized square coils arranged in the zigzag configuration, which provides a better uniform magnetic flux density compared with another configuration. The stator is a compact and portable module with built-in current amplifier units. The single-disc magnet mover is deployed with five controllable degrees of freedom. The cross-coupling effect is decoupled by a precomputed Lorentz force based wrench—current transformation matrix stored in the lookup table. A 2-D linear interpolation is implemented to enhance decoupling effectiveness which is offered via discrete lookup data. Experiments with motion-tracking cameras and a basic controller demonstrate the results of fine step motion of 10 and 20 µm and rotation steps of 0.5 and 1.0 mrad. The potential for multidirectional material handling is represented by a total horizontal translation range of 20 mm by 20 mm with a maximum air gap of 26 mm and a total rotation range of 20 degrees for both roll and pitch.

Scalability of U-Shape Magnetic Nanoparticles-Based Microreactor–Lipase-Catalyzed Preparative Scale Kinetic Resolutions of Drug-like Fragments

The production of active pharmaceutical ingredients (APIs) and fine chemicals is accelerating due to the advent of novel microreactors and new materials for immobilizing customized biocatalysts that permit long-term use in continuous-flow reactors. This work studied the scalability of a tunable U-shape magnetic nanoparticles (MNPs)-based microreactor. The reactor consisted of a polytetrafluoroethylene tube (PTFE) of various inner diameters (ID = 0.75 mm, 1.50 mm, or 2.15 mm) and six movable permanent magnets positioned under the tube to create reaction chambers allowing the fluid reaction mixture to flow through and above the enzyme-loaded MNPs anchored by permanent magnets. The microreactors with various tube sizes and MNP capacities were tested with the preparative scale kinetic resolution of the drug-like alcohols 4-(3,4-dihydroisoquinolin-2(1H)-yl)butan-2-ol (±)-1a and 4-(3,4-dihydroquinolin-1(2H)-yl)butan-2-ol (±)-1b, utilizing Lipase B from Candida antarctica immobilized covalently onto MNPs, leading to highly enantioenriched products [(R)-2a,b and (S)-1a,b]. The results in the U-shape MNP flow reactor were compared with reactions in the batch mode with CaLB-MNPs using similar conditions. Of the three different systems, the one with ID = 1.50 mm showed the best balance between the maximum loading capacity of biocatalysts in the reactor and the most effective cross-section area. The results showed that this U-shaped tubular microreactor might be a simple and flexible instrument for many processes in biocatalysis, providing an easy-to-set-up alternative to existing techniques.

Study of magnetic microspheres screening in microfluidic chip based on co-simulation method

Magnetic microspheres have been widely applied in DNA determination, bacterial analysis, and information coding. Magnetic microspheres screening is important, as the sizes of the obtained microspheres vary with different manufacturing methods, causing considerable impact on subsequent applications. In this paper, a co-simulation method based on MATLAB and COMSOL was presented to design the magnetic microfluidic chip, which was utilized to separate the magnetic micro-spheres of different sizes efficiently. In order to complete the separation and screening of magnetic microspheres in the microchannel, a movable permanent magnet device was adopted to adjust the magnetic interactions in the separation area, allowing the microspheres to deviate from different distances. A batch analysis of chip model was performed with this method, and an optimal design that showed high efficiency in separating microspheres of different sizes and magnetic properties was also revealed. Moreover, detailed analysis focused on the influence of flow rate, magnetism and arrangement of magnets on the separation effect of the chip. The presented simulation method will not only shorten the chip design time but also have a better understanding of the factors that can affect the separation of particles. This study has shown its potential in the computer-aided design of microfluidic chips for magnetic microspheres screening.

Small excitation self-powered sensing energy harvester for rail traffic condition monitoring

A small excitation bistable vibration energy harvester for railway transportation is developed for self-powered condition monitoring utilizing low-frequency vibration of key train components. Analyze operational vibration data collected from trains to determine design requirements. A free sliding magnet is placed in a tube with a top fixed magnet and two limit springs, using gravity, magnetism, and spring force to provide two stable positions for the movable magnet. This structure can enter the bistable operating region under small excitation amplitude and has a wide operating bandwidth. Build and test prototypes using conditions similar to real train operating conditions. A wide operating bandwidth (7 Hz-46 Hz) is obtained due to the bistability. Peak output power is 3.17mW measured into a 900 Ω resistive load at 30 Hz and 1.4g.

Analysis and Experiments of a Pendulum Vibration Energy Harvester With a Magnetic Multi-Stable Mechanism

This work couples a magnetic multi-stable mechanism to a pendulum vibration energy harvester so as to widen its bandwidth, especially in low-frequency operation. Multiple stable points are formed by a movable permanent magnet installed on the pendulum and two fixed permanent magnets installed symmetrically on the base of the energy harvester. Thus, the pendulum can swing between the stable points at two sides, which causes large motion amplitude and power generation. In designing the prototype of the energy harvester, dynamical modeling and potential energy analysis are carried out to achieve a low threshold for snap through. An experimental setup is developed and a series of comparative experiments are implemented to investigate prototype performance. It is shown that the energy harvester with the fixed magnets can generate a noticeable normalized induced voltage at 0.7 Hz, while the energy harvester without the fixed magnets requires the excitation frequency of 1.0 Hz to reach a similar level. The electrical outputs varying with vibration acceleration and load resistance are also examined. In general, the experimental results verify the effectiveness of the proposed structure on enlarging frequency bandwidth. This work can provide a promising candidate of energy harvesting for low-frequency applications such as ocean wave.

Toward effective irregular wind energy harvesting: Self-adaptive mechanical design strategy of triboelectric-electromagnetic hybrid wind energy harvester for wireless environmental monitoring and green hydrogen production

Wind energy, which has been attracting attention as a sustainable clean energy for carbon neutrality, needs to be efficiently harvested in consideration of the intrinsic mechanical characteristics of wind in the natural environment. In this study, we suggest the self-adaptive triboelectric-electromagnetic hybrid wind energy harvester (SA-TEH), which can effectively harvest the wind energy by adopting the movable magnet based rational mechanical analysis-based design strategy. The SA-TEH can be effectively operated regardless of wind speed by automatically modulating its energy acceptability that mechanically limits the total amount of mechanical energy acceptable to a given mechanical system. The outstanding effectiveness of the adaptive mechanical design is verified in that the energy conversion efficiency of the SA-TEH is maximized up to approximately 60 times higher than the fixed mechanical designed energy harvester in the specific wind environment. Furthermore, the present SA-TEH enables to successfully operate of both the real-time wireless environmental monitoring system and the wireless hydrogen fuel cell-powered vehicles without an external power supply. Therefore, the proposed rational adaptive mechanical design-based output enhancement strategy not only provides the design guideline for small-sized energy harvesters but exhibits the crucial role of classical mechanics in the state-of-the-art technology to bring unexpectedly tremendous ripple effects.

Electrodynamic long-stroke drive as an inertial compensator of low-frequency vibroactive forces

The article discusses various possibilities of using an electrodynamic drive with an increased displacement of a movable permanent magnet as a low-frequency inertial compensator of vibroactive forces.The main attention is paid to the analysis of an active dynamic vibration damper (ADVD) when installing an electrodynamic compensator (EDC) on the base near vibration supports and when connecting the EDC moving mass with a vibroactive mass using a spring. It is shown that the considered ADVD is effective as a vibration isolator in the low-frequency range.

Proizvodnja i ispitivanje elektormagnetnih generatora milimetarske skale za udarne kretnje visokih amplituda

Environment vibrations are an important source of energy, often occurring at very low frequencies, but with large amplitude. The possibility to use the large amplitude of the motions is important to enhance the energy harvester's output power. In this paper, an electromagnetic energy harvester is designed and fabricated to produce electricity from low- frequency high amplitude impact motions using an elastic polyurethane cylinder. This millimeter-scale electromagnetic generator (MS-EMG) includes a movable magnet attached to a free sliding mass, a fixed coil, and a polyurethane holding chamber. Polyurethane is a very stable elastic polymer that provides continuous large-amplitude movement for the magnet and plays an effective role in impact capability. Therefore, the effect of impact excitation and the polyurethane foam was investigated simultaneously. The performance of the device was studied, experimentally, for the environment vibrations in the range of 1 to 10 Hz. The impact motions were applied using a simulator that was fabricated for this work. The fabricated MS-EMG with a volume of 1.07 cm3 and a mass of 8.74 g show the capability of producing a voltage of 44.41 mV and power of 10.48 µW over a 100 Oresistive load, using a 6 Hz frequency impact motion. Finally, an analytical model is used to simulate the device performance which showed a good agreement with the experimental results.

Tuned bistable nonlinear energy sink for simultaneously improved vibration suppression and energy harvesting

Despite the combination of nonlinear vibration suppression (VS) and energy harvesting (EH) has received great attention in recent years, the strategy to simultaneously improve the performance in both purposes and extend the operating amplitude range to low-level excitations is still an open issue. To achieve this goal, this paper proposes a tuned bistable nonlinear energy sink (TBNES) to outperform the typical bistable nonlinear energy sink (BNES). The TBNES replaces the fixed magnet that is opposite to the bistable piezoelectric beam (BPB) in the BNES by a tuning piezoelectric beam (TPB) with a movable tip magnet. On one hand, the TPB with a linear viscous damping and a piezoelectric element can improve both VS and EH performances. On the other hand, the tuning effect can dynamically reduce the elastic potential barrier of the BPB, helping it induce the initial snap-through motion and produce the strong targeted energy transfer at low-level excitations, therefore leading to the extension of its operating amplitude range. The electromechanical model and the magnetic force model are derived for both TBNES and BNES based on Hamilton’s principle and the geometrical dipole–dipole method. Parametric studies are conducted to investigate the influences of key system parameters on their VS and EH performances with three defined figure of merits. With the system parameters optimized by the presented dynamic optimization algorithm, the simulation results show that the performance of the TBNES is better than that of the BNES in VS and EH, and its operating range of excitation amplitudes can be successfully extended. The deep mechanisms for these phenomena are discussed from the aspects of 1:1 resonance, induction of nonlinearity, elastic potential energy, etc.

A single-sided magnet for deep-depth fat quantification

Early detection of fatty-liver disease is important before further aggravations of the disease, such as cirrhosis, can develop. In this study, we developed a low-cost, movable single-sided magnet for in vivo liver fat quantification. A gradient field of 73.5 G/cm and a field strength of 0.0725 T were obtained by structurally optimizing the concave U-shaped magnet, on which the region of interest (ROI) was a curved shape about 0.4 mm thick, 8 cm above the surface of the radiofrequency (RF) coil. We constructed a prototype nuclear magnetic-resonance (NMR) relaxometry system based on this optimized magnet. Subsequent phantom experiments demonstrated the effectiveness of the single-sided magnet in evaluating different proton density fat fraction (PDFF) phantoms. As expected, the results of the six phantoms showed good positive correlation between PDFF and the fitted fat amplitude, which suggested that single-sided NMR relaxometry could be used to quantify liver fat in vivo.