Levitated Plate Research Articles

Tangential motion mechanism and reverse hydrodynamic effects of acoustic platform with nonparallel squeeze film

In order to explain the reverse hydrodynamic effects on acoustic platform with nonparallel squeeze film, a theoretical model was proposed to evaluate the levitation and movement capacity in this paper. The mechanism of movement and levitation was revealed by the viscous fluid mechanics and dynamic lubrication theory. The transient pressure gradient and steady average velocity were calculated in different deflection angles of nonparallel squeeze film by means of numerical calculation of Reynolds equation. The theoretical results indicated that the platform of nonparallel squeeze film was provided with a bearing and pushing capacity in both normal and tangential directions and it was amazing that the reverse hydrodynamic effects made the levitated plate move into the opposite direction of gravitational tangential component. This proposed theoretical model for acoustic platform with nonparallel squeeze film was different with the original parallel one. Its driving mechanism was the reverse hydrodynamic effect instead of travelling waves. This reverse hydrodynamic effect was proved in the experiments, which could be used in levitation and transport field for precise component in future.

Theoretical investigation and prototype design for non-parallel squeeze film movement platform driven by standing waves

Abstract In order to realize contactless levitation and movement of precision components, a new kind of acoustic prototype driven by standing waves utilizing reverse hydrodynamic effects of non-parallel squeeze film was proposed in this paper. Its mechanism of movement and levitation was revealed by the viscous fluid mechanics and dynamic lubrication theory. It is amazing that the reverse hydrodynamic effects made the levitated plate move along the opposite direction of gravitational tangential component, which was proved in the experiments. The bearing and pushing capacity is predicted by numerical calculation of Reynolds equation and a CFX model. A dimensionless parameter 'voltage difference ratio' was proposed to evaluate the deflection angle of a non-parallel squeeze film, which can guide the prototype design.

202 近距離場音波浮揚による非接触加振の研究(セッション5 音響・超音波利用)

This study concerns non-contact excitation of planer objects by using near-field acoustic levitation, in which a planer object having relatively large size and weight is levitated on a ultrasonic vibration plate with 10-100 μm air gap. This phenomenon has been studied as a non-contact transportation technology for a fragile thin plate such as flat panel display glass substrate. In this study, we investigate the possibility of this phenomenon as a technology for non-contact excitation of planer objects. In this paper, we propose a non-contact excitation method to vibrate the levitated object at arbitrary low frequency by modulating the ultrasonic amplitude of the vibration plate. An experimental study of non-contact excitation of plate specimens near the natural frequencies suggests that the system consisting of the vibration plate, the air gap, and the levitated plate can be modeled as a two-degree-of-freedom dynamical system.

Fuzzy logic control of electrodynamic levitation devices coupled to dynamic finite volume method analysis

Electrodynamic levitation devices, which utilizing eddy currents induced in the levitated item to produce the repulsive force, are being involved in many engineering applications due to its fast response. This kind of repulsion is particularly used in electromagnetic launcher, electromagnetic brake and other applications. To analyze and improve the dynamic behavior and performances of such devices, the conventional way is using the finite element method (FEM), due to its ability of using adaptive mesh to handle complex geometries. Nevertheless, it has a serious limitation in efficiency for large number of variables which is reflected by the high cost in terms of computational properties. During the past few years, the finite volume method FVM formulations have gained attention inside the electromagnetic community. The method has been proved its effectiveness in the solution of different kinds of problems, such as in magnetostatic field computation and eddy current nondestructive testing. The FVM method is particularly attractive thanks to its small required storage memory and reduced CPU time. In this paper an FVM model is developed to analyze the dynamic characteristic of the motion of the electrodynamic levitation device TEAM Workshop Problem 28. The dynamic characteristic of the motion is obtained by solving the electromagnetic equation coupled to the mechanical one. The repulsive force applied to the levitated plate of TEAM Workshop Problem 28, is computed by the interaction between eddy current induced in the plate and the magnetic flux density. A comparison between experimental and numerical results is carried out to show the efficiency of the developed model. What’s more, based on the developed FVM model, a fuzzy logic controller FLC is designed and implemented to control the position of the levitated item.

Precision stage using a non-contact planar actuator based on magnetic suspension technology

The precision stage using a novel contact-free planar actuator based on magnetic forces, magnetized force and Lorentz force, is suggested. In the promising magnetic structure, a mover is levitated by magnetized force between iron-core electromagnets attached under the upper-side of a stator and ferromagnetic plates belonging to the mover. And the mover is driven by Lorentz force that acts on permanent magnets with an identical polarity put under magnetic field by air-core coils. Namely, the mover is driven directly without any transmission mechanism, and does not need any auxiliary driver for its posture calibration. Then it is estimated that the proposed operating principle is very suitable for work requiring high accuracy and cleanness, or general-purpose nano-stage. In this paper, we discuss a driving principle of the planar system including the magnetic force generation mechanism, a framework for the force model, governing characteristics of the levitated plate, and a planar motion control of the constructed prototype. And experimental results are given to verify the derived theoretical model and the feasibility of the system.

Study on a novel contact-free planar system using direct drive DC coils and permanent magnets

To cope with the severe specification such as a concurrent realization of high accuracy and wide operating range demanded in many fields, we suggest a contact-free planar system that realizes the spatial motion of a plate by generating a levitation force and a thrust force at the same plane concurrently. The system utilizes an interaction between the direct drive DC coils of a common shape and the permanent magnets with a coincident polar direction and, thus, it is very easy to implement and simple to quantify the magnetic interaction. We discuss a driving principle of the planar system including magnetic force generation mechanism, a framework for the force model, governing characteristics of the levitated plate and a planar motion control of the constructed prototype. The experimental results are given to verify the derived theoretical model and the feasibility of the system.

자기 흡인식 부상 원리에 기초한 비접촉식 서피스 액추에이터의 초정밀 범용 스테이지에의 적용 가능성

The precision stage using a novel contact-free planar actuator based on magnetic farces, magnetized force and Lorentz farce, is suggested. In the promising magnetic structure, the mover is driven directly without any transmission mechanism, and doesn`t need any auxiliary driver for its posture calibration. Then it is estimated that the proposed operating principle is very suitable for work requiring high accuracy and cleanness, or general-purpose nano-stage. In this paper, we discuss a driving principle of the planar system including the magnetic force generation mechanism, a framework for the force model, governing characteristics of the levitated plate, and a planar motion control of the constructed prototype. And experimental results are given to verify the derived theoretical model and a feasibility of the system.

Magnetic Levitation System of a Flexible Steel Plate with Vibration Suppressing Electromagnets.

A magnetic levitation system is applied to the non-contacting conveyance of steel plate in a steel mill. In this system, the flexibility of the steel plate may deteriorate the levitation characteristic and so it is proposed to arrange the electromagnets along the steel plate length. A low pass filter is used to reduce the influence of the steel plate natural vibrations. Simulation results of the levitated plate's response by a finite element method and magnetic levitation experiments are presented. The results show the vibration suppressing electromagnet which only uses the velocity of the levitated object as a feedback is able to control the low frequency natural vibration effectively and a low pass filter is able to avoid the excitation of the high frequency natural vibration.

Magnetic levitation of a flexible steel plate with a vibration suppressing magnet

A magnetic levitation system that has a vibration suppressing electromagnet which use only the velocity of the levitated object for the control has been studied. The proposed system has advantages of the stable levitation of a flexible steel plate which moves with time under the fixed electromagnets. The simulation of levitated plate's response using finite element method and the magnetic levitation experiments using such a vibration suppressing magnet were carried out. The results show the vibration suppressing magnet is able to control the low frequency natural vibration effectively, and a notch filter is able to avoid the excitation of the high frequency natural vibration.