Stable Levitation Research Articles

Modeling Development of a Diamagnetically Stabilized Magnetically Levitated Gravimeter.

The aim of this work is to create a new type of gravimeter that can function effectively in the challenging conditions of space, specifically on the surfaces of planets and moons. The proposed device, called a diamagnetically stabilized magnetically levitated gravimeter (DSMLG), uses magnetic forces to balance a test mass against the force of gravity, allowing for accurate measurements. A diamagnetically stabilized levitation structure comprises a floating magnet, diamagnetic material, and a lifting magnet. The floating magnet levitates between two diamagnetic plates without the need for external energy input due to the interaction between the magnetic forces of the floating magnet and the stabilizing force of the diamagnetic material. This structure allows for stable levitation of the floating magnet without requiring additional energy. The goal is to design a gravimeter that is lightweight, requires minimal power, can withstand extreme temperatures and shocks, and has a low data rate. The authors envision this gravimeter being used on various robotic spacecraft, such as landers and rovers, to study the interiors of rocky and icy celestial bodies. This paper reports on the results of a finite element model analysis of the DSMLG and the strength of the resulting diamagnetic spring. The findings contribute to the understanding of the levitation characteristics of diamagnetically stabilized structures and provide valuable insights for their practical applications, including in the development of the proposed DSMLG.

ЧИСЛЕННАЯ МОДЕЛЬ КАК КОМПОНЕНТ СИСТЕМЫ УПРАВЛЕНИЯ ЭЛЕКТРОМАГНИТНОЙ ПЛАВКОЙ МЕТАЛЛОВ ВО ВЗВЕШЕННОМ СОСТОЯНИИ

The work presents the results of numerical simulation of the process of levitation melting of metal in an electromagnetic field. The developed model reflects the retention of the heated sample in a state of stable levitation. Based on the constructed model, a study of the levitation melting process was carried out, taking into account the technical characteristics of the laboratory equipment. During the experiments, the zone of stable levitation of the sample with the specified parameters in the alternating electromagnetic field was determined. The efficiency of the obtained numerical model and its suitability for use as part of a real-time technological process control system for melting were evaluated.

Environmental conical nozzle levitator equipped with dual wavelength lasers

AbstractThe environmental conical nozzle levitator (E‐CNL) with dual‐wavelength lasers is an extreme environment materials characterization system that was designed to investigate ultra‐high‐temperature materials: refractory metals, oxides, carbides, and borides above 3000 K in a controlled atmosphere. This article details the characterizations using this system to establish its high‐temperature capabilities and to outline ongoing work on materials under extreme conditions. The system has been used to measure the melting point of several oxide materials (TiO2, Tm = 2091 ± 3 K; Al2O3, Tm = 2310 3 K; ZrO2, Tm = 2984 31 K; and HfO2, Tm = 3199 ± 45 K) and several air‐sensitive refractory metals (Ni, Tm = 1740 K; Ti, Tm = 1983 K; Nb, Tm = 2701 K; and Ta, Tm = 3368 K—note: mean ± standard deviation) during levitation which matched literature values within 0.17–2.43 % demonstrating high accuracy and precision. This containerless measurement approach is critical for probing properties without container‐derived contamination, and dual‐wavelength laser heating is essential to heat both relatively poor electrical conductors (some refractory metals and carbides) and insulators (oxides). The highest temperature achieved utilizing both lasers in these experiments was ∼4250 ± 34 K on a 76.6 mg, molten HfO2 sample using a normal spectral emissivity of 0.91. Stable levitation was demonstrated on spherical samples (yttria‐stabilized zirconia) while adjusting levitation gas composition from pure oxygen to pure argon, verifying atmospheric control up to 3173 K on solid or molten samples. These successes demonstrate the viability of in situ high‐temperature environmentally controlled studies potentially up to 4000 K on all classes of ultra‐high‐temperature materials in one system. These measurements highlight the E‐CNL system will be essential for the development of next‐generation ultra‐high‐temperature materials for hypersonic platforms, nuclear fission and fusion, and space exploration.

Concise magnetic force model for Halbach-type magnet arrays and its application in permanent magnetic guideway optimization

In maglev trains, a permanent magnetic guideway (PMG) is an indispensable component that influences their levitation stability. PMG generates the magnetic repulsion force in permanent magnetic levitation and provides the pinning force via coupling with bulk superconductors in superconducting magnetic levitation. Typically, they are arranged in a Halbach array to enhance the magnetic force. However, the spatial inhomogeneous feature of magnetic field makes magnetic force acquisition of the double-sided Halbach array extremely difficult. For accurate magnetic force acquisition, this study proposes a concise analytical magnetic force model and elucidates upon its field behavior. Based on this, a finite element method (FEM) model was developed and verified. The experimental results demonstrated that the Halbach-type PMG’s field distribution was effectively reproduced. Subsequently, the accuracy of the was obtained via comparison with the FEM. The calculation results revealed that the increase in the levitation force tends to be saturated as more magnets are used. For a feasible PMG configuration in terms of high levitation force and low lateral force, the structural parameters were optimized using the multi-objective particle swarm optimization (MOSPO) algorithm combined with the identified magnetic force formulas. The results and findings of this study have significant implications for the design optimization of guideway configurations that heavily rely on permanent magnets.

Motion Control of Capsule Robot Based on Adaptive Magnetic Levitation Using Electromagnetic Coil

In view of the magnetically actuated capsule robot applications in diagnoses of human stomach disease, the challenges that are associated with degrees-of-freedom (DOF), environmental adaptability, and the size of the entire system must be addressed. In this study, a new electromagnetic coil system that is based on adaptive magnetic levitation is presented; it is mainly composed of an independent orientation control electromagnetic coil and a magnetic levitation control electromagnetic coil. The system is designed to perform motion control of the capsule, including 3-DOF levitating translational motion control, and pitch and yaw motion control in levitation. In this manner, it compensates for the lack of previous magnetic levitation systems that were based on electromagnetic coils for the control of the tilt angle of the capsule. With torque-based actuation control, the tilt angle of the capsule can be controlled continuously with an angle increment of no more than 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> (within 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> ) during levitation. The capsule under the magnetic levitation control, which is based on the fuzzy proportional-integral -derivative controller, can maintain the stability of levitation; the error between the actual capsule position and the required position did not exceed 0.1 mm when the capsule was out of water or completely immersed in it. Moreover, the experiment of the capsule levitating from air to water further verifies the adaptability of the system with regard to the environment; this provides a new examination method for capsule endoscopy. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This work is caused by the motion manipulation problem of a magnetically driven capsule robot. Most of the existing magnetically driven capsule robots use a rolling or sliding method that fits tightly against the stomach wall, and these forms of motion make it possible to risk missing diagnoses in the examination of gastric diseases, and the maneuverability limits its further application. This paper proposes an adaptive control strategy for a magnetically driven capsule robot based on magnetic levitation motion. It allows the magnetically driven capsule robot to levitate to any position in the stomach for photography and observation without external mechanical support, and this levitation motion is sufficiently stable. In addition, the proposed capsule robot has independent orientation and position control, which has the potential to achieve automated inspection.

Stabilizing Diamagnetic Levitation of a Graphene Flake through the Casimir Effect

Graphene exhibits diamagnetism, enabling it to be lifted by the repulsive force produced in an inhomogeneous magnetic field. However, the stable levitation of a graphene flake perpendicular to the magnetic field is impeded by its strong anisotropic of magnetic susceptibility that induces rotation. A method to suppress this rotation by applying the Casimir force to the graphene flake is presented in this paper. As a result, the graphene flake can archive stable levitation on a silicon plate when the gravitational force is small.

5-axes Levitation of a Rotor by Active Magnetic Bearings Employing Direct Output Feedback Control

In recent years the application of active magnetic bearings (AMB), as supporting element as well as vibration controller for rotors, has attracted considerable attention from researchers. In this work an attempt has been made for the complete levitation of a rotor weighing 4 kg, supported on two radial active magnetic bearings and two axial passive magnetic bearings (PMB) resulting in 5-axes levitation. The active bearings working in the mode of attraction make the system inherently unstable. Herein, a direct output feedback control scheme based on proportional and derivative of position signal has been employed to achieve stability. The active magnetic bearings consist of electromagnetic actuators, proximity probes for position measurement, feedback controller and current feedback type power amplifier. The passive bearings consisting of axially magnetized circular permanent magnets work in the mode of repulsion. The design of the electromagnetic actuator has been carried out considering load carrying capacity of the AMB, core loss and the resistive loss in the coil, so that the temperature rise in the core as well as in the coil is within allowable limit. Design of the feedback controller is based on direct output feedback control scheme, which makes the controller design easier and implementation of the controller hardware becomes simpler. The feedback controller parameters have been selected appropriately to generate required stiffness and damping in the AMBs for stable levitation of the rotor. The rotor has been driven up to a speed of 2000 rpm.

Experimental Verification of the Suppression Effect of a Gyroscopic Damper on Nonlinear Resonance in a High-Temperature Superconducting Magnetic Levitation System

This paper presents experimental verification of the vibration suppression effect of a gyroscopic damper on a system supported elastically by a superconducting magnetic levitation system when subjected to vibration. While superconducting magnetic levitation systems are capable of uncontrolled and stable levitation, they are prone to multi-degree-of-freedom vibration and nonlinear vibration of the levitating body due to their low damping. In our previous study, we have numerically predicted that a gyroscopic damper, a passive vibration control method, may be effective in simultaneously suppressing translational and tilting vibrations by optimizing the design parameters. In this paper, this vibration suppression effect predicted was investigated through experiments. In the experiment, nonlinear vibration of the levitating body occurred, which may have been caused by the magnetic force of the superconductivity, but the motion coupling of the gyroscopic damper and the levitating body was found to reduce that vibration by 30% in the translational direction and by 40% in the tilting direction. The gyroscopic damper was thus demonstrated to be effective in simultaneously suppressing the translational and tilting vibration of the levitating body.

Particle size effects on stable levitation positions in acoustic standing waves.

Schlieren images can show a two-dimensional representation of pressure distributions. Using this method, we have demonstrated that there is a particle size effect for levitating solid elastic Styrofoam spheres in an ultrasonic acoustic standing wave: (1) spheres of density 13.3 kg/m3 and diameters less than 0.58 λ levitate at pressure nodes, and (2) spheres larger than 0.66 λ levitate with their centers at pressure antinodes. Pressure measurements of ultrasonic standing waves made in conjunction with their schlieren images to identify pressure nodes and antinodes are presented. These observations contribute to prior experimental and theoretical research concerning the influence of particle size on levitation.

Pyrolytic Graphite for an In-Plane Force Study of Diamagnetic Levitation: A Potential Microdetector of Cracks in Magnetic Material.

The diamagnetic levitation technique can be applied in non-destructive testing for identifying cracks and defects in magnetic materials. Pyrolytic graphite is a material that can be leveraged in micromachines due to its no-power diamagnetic levitation on a permanent magnet (PM) array. However, the damping force applied to pyrolytic graphite prevents it from maintaining continuous motion along the PM array. This study investigated the diamagnetic levitation process of pyrolytic graphite on a permanent magnet array from various aspects and drew several important conclusions. Firstly, the intersection points on the permanent magnet array had the lowest potential energy and validated the stable levitation of pyrolytic graphite on these points. Secondly, the force exerted on the pyrolytic graphite during in-plane motion was at the micronewton level. The magnitude of the in-plane force and the stable time of the pyrolytic graphite were related to the size ratio between it and the PM. During the fixed-axis rotation process, the friction coefficient and friction force decreased as the rotational speed decreased. Smaller-sized pyrolytic graphite can be used for magnetic detection, precise positioning and other microdevices. The diamagnetic levitation of pyrolytic graphite can also be used for detecting cracks and defects in magnetic materials. We hope this technique will be used in crack detection, magnetic detection and other micromachines.

Experimental Implementation of a Magnetic Levitation System for Laser-Directed Energy Deposition via Powder Feeding Additive Manufacturing Applications

Magnetic levitation and additive manufacturing (AM) are two fields of significant interest in academic research. The use of non-contact forces for magnetic levitation techniques provides opportunities for adoption within the AM environment. The key goal of this article is to experimentally validate the implementation of a magnetic levitation system for Laser-Directed Energy Deposition via Powder Feeding (LDED-PF) Additive Manufacturing applications. Through simulations (conducted in ANSYS Maxwell) and experimental implementation, the levitation system’s stability is tested under a variety of different conditions. The experimental implementation highlights the feasibility of a magnetic levitation system for LDED-PF applications. The levitation system developed is capable of the suspension of non-magnetic materials. The system is also able to maintain stable levitation for extended periods of time. The incorporation of the levitation system into the AM environment may result in an increased maneuverability of non-clamped structures for AM deposition operations.

Comparative Analysis and Experiment Verification of Diamagnetically Stable Levitation Structure

In this paper, a new diamagnetic levitation structure is proposed to explore its potential in the application of sensors and actuators through the study of its levitation and dynamic characteristics. Compared with our old diamagnetic levitation structure, the levitation point, maximum monostable levitation space, horizontal magnetic spring stiffness, and axial resultant force distribution of the new structure are all adjustable. At the same time, the maximum horizontal radial recovery force of the floating magnet could reach 34780 μN, which is 542.41% higher than that of the floating magnet in the old structure. Accordingly, when the range of the horizontal radial displacement is 0 to 15 mm, the maximum axial resultant force of the floating magnet is 439.7 μN, which is only 5.72% of that in the old structure. In experiment, when the floating magnet is blown by nitrogen gas with a flow rate of 3000 sccm, the maximum horizontal radial displacement of the floating magnet is 2.27 mm, which is only 22.976% of that in the old structure. Under the same gas flow rate, the maximum tilt angle of the floating magnet is 0.482°, which is only 3.998% of that in the old structure. In summary, the theoretical analysis, numerical simulation, and experiment results are consistent with each other, which indicates the great potential of the new structure in the application of sensors and actuators.

Dynamically Rotating Magnetic Levitation to Characterize the Spatial Density Heterogeneity of Materials.

Magnetic levitation (MagLev) is a promising technology for density-based analysis and manipulation of nonmagnetic materials. One major limitation is that extant MagLev methods are based on the static balance of gravitational-magnetic forces, thereby leading to an inability to resolve interior differences in density. Here a new strategy called "dynamically rotating MagLev" is proposed, which combines centrifugal force and nonlinear magnetic force to amplify the interior differences in density. The design of the nonlinear magnetic force in tandem with centrifugal force supports the regulation of stable equilibriums, enabling different homogeneous objects to reach distinguishable equilibrium orientations. Without reducing the magnetic susceptibility, the dynamically rotating MagLev system can lead to a relatively large change in orientation angle (∆ψ>50°) for the heterogeneous parts with small inclusions (volume fraction VF = 2.08%). The rich equilibrium states of levitating objects invoke the concept of levitation stability, which is employed, for the first time, to characterize the spatial density heterogeneity of objects. Exploiting the tunable nonlinear levitation behaviors of objects provides a new paradigm for developing operationally simple, nondestructive density heterogeneity characterization methods. Such methods have tremendous potential in applications related to sorting, orienting, and assembling objects in three dimensions.

Influence of suspension schemes on medium-low speed maglev vehicle-guideway dynamic interaction

A comparative study was conducted on Levitation Frame with Mid-set Air Spring (LFMAS) and Levitation Frame with End-set Air Spring (LFEAS). First of all, the work done by air spring force and by track excitation on two levitation frames were analysed, respectively, and the mechanism of the low dynamic interaction of LFMAS with guideway was explained theoretically; then, dynamics simulation and coupled vibration test on LFEAS and LFMAS were carried out using coupled vibration test bench of single levitation frame. Theoretical equations show that both the work done by the air spring forces and by track excitation on LFMAS are less than those on LFEAS under the same vibration condition, demonstrating that LFMAS has better levitation stability than LFEAS. Simulation and test results show that the fluctuation of levitation gap as well as the vibration acceleration of track beam platform, levitation frame and car-body of LFMAS are all smaller than those of LFEAS; with the increase of sine excitation frequency or vehicle speed, the superiority of LFMAS in dynamics performance is more obvious.

Bending levitation control of flexible steel plate: Consideration of effect of magnetic properties on electromagnetically levitated steel plate vibration

Recently, demand for thin steel plates has increased. In the manufacturing of thin steel plates, surface quality deterioration due to contact between the rollers and steel plate involved is problematic. We are investigating magnetic levitation conveyance to propose a noncontact conveyance system using electromagnets. However, the magnetic levitation of thin steel plates is unstable because of the deflection in the range where the electromagnetic force is not affected. Therefore, to improve the levitation stability, we are investigating a bending magnetic levitation system in which a thin steel plate is bent during magnetic levitation but not deformed plastically. In this study, a dynamic analysis using the finite difference method is performed to understand the behavior of a thin steel plate during magnetic levitation. In the dynamic analysis, vibration is evaluated based on the displacement standard deviation. The dynamic simulation visualizes the dynamic behavior of a levitated flexible steel plate.

Control Methods for Levitation System of EMS-Type Maglev Vehicles: An Overview

As new advanced vehicles, electromagnetic suspension (EMS)-type maglev trains have received wide attention because of their advantages such as high speed, no mechanical friction, low noise, low cost and energy consumption, strong climbing ability, and green environmental protection. The open-loop instability is one of the key points and difficulties for the levitation control systems of maglev trains. The closed-loop feedback control method must be applied to realize stable levitation. However, there are currently many levitation control methods just in theory. Considering their advantages and disadvantages, it is a major demand for maglev trains to select efficient, stable, applicable, and cost-saving methods to improve their dynamic performance and safety, which motivated this review. First, the current status of research on maglev trains is introduced in this paper, including types, system components, and research modes in various countries, followed by an analysis of the levitation control methods for EMS-type maglev trains. Then, the technical characteristics of the levitation control systems are described according to the basic principles of levitation systems, model building, mathematical derivation, and control objectives. Next, three kinds of typical levitation control methods are reviewed, namely, linear state feedback methods, nonlinear control methods, and intelligent control methods, according to their improvements and applications. Lastly, we summarize and evaluate the advantages and disadvantages of the three methods, and future developments of levitation control are suggested.

Novel Bearingless Motor Topology With Diamagnetic Salient-Pole Rotor

This article proposes a novel bearingless motor topology with diamagnetic salient-pole rotor. The material of the rotor is pyrolytic graphite (PG) so that five degrees of freedom of the rotor are passively stabilized above a permanent magnet array. The stator consists of two components: a Halbach permanent magnet array and an axial-flux stator core with twelve teeth holding the eight-pole three-phase winding. Passive levitation forces are generated between the permanent magnet unit and the PG rotor. Rotating torque is generated between the stator core and the PG rotor. In this paper, the principle of the five-axis passively stabilized bearingless motor with the PG rotor is outlined. In experiments, passive axial forces and an acceleration process are measured. In the test, open-loop speed control is used. The proof-of-concept successfully achieves stable passive levitation, and allows acceleration up to 200 r/min.

The impact of magnetic field periodicity on the hysteresis loss in superconducting magnetic bearings

Since the discovery of high-temperature superconductors (HTS), superconducting magnetic bearings (SMB) have attracted much attention for practical applications such as flywheel energy storage systems, electrical machines, gyroscopes, etc., because of their ability to provide passive stable levitation under high-load conditions. Despite providing contactless linear and rotational motion, SMBs gradually decelerate by AC losses mainly generated by magnetic field inhomogeneity. The main component of AC losses at low rotational speeds is hysteresis loss, which is said to be independent of rotational speed, intrinsic to HTS, and proportional to the cube of magnetic field inhomogeneity. Although the state-of-the-art analytical expression of hysteresis loss in SMBs captures the general physics of the loss mechanism, it ignores the periodicity of the magnetic field in one complete rotation of the bearing. In this paper, the analytical expression of hysteresis loss is modified, taking into account the impact of magnetic field periodicity and the distribution of loss over the bearing surface. The new expression is tested by performing spin-down experiments with magnets of different levels of inhomogeneity in an actual SMB environment. The impact of magnetic field inhomogeneity on the dynamic behaviour of the bearing is also investigated. The results show consistency between modified analytical calculations and experimental data.

State Observers and Run-Out Reduction for Magnetically Levitated Motor Systems

Magnetically levitated motor systems create opportunities for new applications of electromechanical power conversion where high-speed and contact-free operation are required. These systems require position sensors and control algorithms for stable levitation which often require filters to reduce feedback noise. Noisy position feedback creates challenges for high-bandwidth estimation of velocity and disturbance force; however, these unmeasured states can be helpful for high-performance control algorithms. This common problem in drives for electric motors has been solved using the Luenberger-style motion state observer. This article investigates the applicability of the observer to digitally-controlled magnetically levitated systems. First, the observer's embedded plant model is derived for discrete-time implementation. Then, it is shown that the most advantageous use-case of the observer is different for magnetically levitated systems versus rotary motor systems. Unlike motor systems, the zero-lag filtering property of observers is minimally useful, while the ability to estimate and reject disturbances yields significant performance improvements for applications that care about run-out. Comprehensive experimental results are provided on a prototype bearingless motor which validate the observer's performance versus frequency and its ability to estimate disturbance forces for use in reducing the rotor run-out. Experimental results achieve over 10× run-out reduction at low-medium speeds while also reducing control current by 50%.

Vertical and lateral random vibration of high-temperature superconductor maglev under high-speed operation conditions

High-temperature superconductor (HTS) maglev systems shows significant potential to be applied to high-speed rail transportation based on its passive stable levitation owing to the coupling between the HTS bulks and permanent magnetic guideway (PMG). As one of the key factors to guarantee the safe and stable operation of HTS maglev, the dynamic characteristics of the HTS bulks reflecting the operational performance of the HTS maglev system under high-speed running conditions should be focused on. Therefore, this paper, based on H-formulation, established a finite element model of an HTS-PMG system, and assessed its feasibility by experiments. Moreover, the random free vibration of the HTS bulk caused by guideway random irregularity at high speed is also studied by this validated model. The random vibration characteristics and temperature variation of the HTS bulk at three high speeds (600 km h−1, 800 km h−1, and 1000 km h−1) under vertical vibration, lateral vibration, and vertical-lateral coupling vibration, respectively, are compared. The results show that at high speed, vertical vibration can only cause the fluctuation of levitation height, while lateral vibration and vertical-lateral coupled vibration will affect both lateral offset and levitation height. Compared with the mere vertical or lateral vibration mode, the levitation height attenuation and temperature rise of the coupling vibration mode is greater due to more energy loss caused by magnetic flux motion, but it can aid in the suppression of the vibration in the vertical and lateral directions. The increase of velocity intensifies the vibration strength of the HTS bulk and increases the fluctuation of the levitation height, lateral offset, and temperature rise. However, vibrations at a certain high speed causes a limited temperature rise and thus a limited influence on the bulk performance, and the HTS bulk is still in the safe operating range at a maximum speed of 1000 km h−1. These conclusions are anticipated to provide some references for future high-speed applications of the HTS maglev system.