6-DOF Magnetic Levitation Research Articles

Modeling and analysis of a novel 6-DOF magnetic levitation system with experimental verification

To improve the uniformity of magnetic flux and increase the stroke of the magnetic levitation system, this paper designs a novel 6-DOF magnetic levitation system and proposes an improved novel Halbach array. First, a repulsive passive magnetic bearing is utilized to provide levitation force, leading to a noticeable reduction in levitation power consumption. Then, a magnetic circuit model for the magnetic levitation system is established, and the improved novel Halbach array is optimized based on this model. Next, the stable levitation model and measurement model for the system are established, and the magnetic field distribution and magnetic bearing stiffness are analyzed. Results indicated an increase of 0.1[Formula: see text]T in the maximum magnetic flux density, accompanied by an improvement in the uniformity of magnetic flux. Additionally, there is an enhancement of 10% in magnetic bearing stiffness. Finally, a prototype of the system is constructed, and the stable levitation simulation and experiment of the actuator are conducted with this system. The maximum levitation absolute displacement error obtained by simulation is about 655[Formula: see text]nm, and the experimental results exhibited a maximum levitation absolute displacement error of approximately 750 nm for the system, confirming the effectiveness of the proposed modeling method.

A Study on the Control Method of 6-DOF Magnetic Levitation System Using Non-Contact Position Sensors

Recently, due to the development of semiconductor technology, high-performance memory and digital convergence technology that integrates and implements various functions into one semiconductor chip has been regarded as the next-generation core technology. In the semiconductor manufacturing process, various motors are being applied for automated processes and high product reliability. However, dust and shaft loss due to mechanical friction of a general motor system composed of motor-bearing are problematic for semiconductor wafer processing. In addition, in the edge bread remove (EBR) process after the photoresist application process, a nozzle position control system for removing unnecessary portions of the wafer edge is absolutely necessary. Therefore, in this paper, in order to solve the problems occurring in the semiconductor process, a six-degrees-of-freedom (6-DOF) magnetic levitation system without shaft and bearing was designed for application to the semiconductor process system; and an integrated driving control algorithm for 6-DOF control (levitation, rotation, tilt (Roll-Pitch), X-Y axis movement) using the force of each current component derived through current vector control was proposed. Finally, the 6-DOF magnetic levitation system with the non-contact position sensors was fabricated and the validity of the 6-DOF magnetic levitation control method proposed in this paper was verified through a performance test using a prototype.

보이스코일모터를 이용한 초정밀 자기부상 스테이지

Voice coil motor is an actuator that employs a non-contact electromagnetic force between its coils and magnets, and is widely used in precision stages on account of its good linearity between current and force. Additionally, these advantages are beneficial for implementing the magnetic levitation mechanism. Unlike the case of general use of a voice coil motor where 1-DOF translational motion is applied, 6-DOF magnetic levitation causes variation in the relative position and orientation between the coil and the magnet. Accordingly, the force constant also changes. In this study, high-level precision positioning of 20 ㎚ was realized through the design and control of a magnetic levitation stage using voice coil motors. In the process, the change in the force of the voice coil motor was found to be approximately 1% within the range of motion. Therefore, the proposed design was verified to be suitable for high-precision stages.

Design and Implementation of an New 6-DoF Magnetic Levitation Positioning System

High-precision magnetic levitation positioning systems are of great interest for many modern applications, because of their absolutely non-contact operation and large planar travel ranges with precisions up to the nanometer range. In this article, a novel six degrees-of-freedom (6-DoF) magnetic levitation (maglev) system, which is based on repulsive levitation forces, is presented. Compared to other known solutions from the literature, this proposed concept allows a freely accessible mover from above in combination with decoupled levitation and propulsion forces. The maglev system consists of eight air-core coils in order to realize a 6-DoF motion. The six-axes position measurement is achieved by four eddy current sensors and four optical laser sensors. After a detailed explanation of the working principle, a decoupled 6-DoF dynamic model is derived and analyzed. Then, based on this dynamic model, simple proportional–integral–differential (PID) controllers are implemented in order to control the unstable behavior of the system. The aim of this article is to demonstrate the functionality of the proposed system. Thus, various experimental results, obtained from the prototype, were conducted to evaluate the dynamic performance of the maglev system. It will be shown that the position errors lie in the range of the sensor resolution and, thus, can be made as small as desired, depending on the applied sensor resolution.

A Novel Design and Control to Improve Positioning Precision and Robustness for a Planar Maglev System

In this paper, we have proposed a novel 6-DOF magnetic levitation (maglev) system to improve the robustness and upgrade positioning precision. The design concept attempts to keep the good performance in the whole journey of moving rather than the point-to-point positioning precision. Furthermore, we endeavor to develop this system with an expectable large moving range. Based on these concepts, we built the force model that considers the variation from the displacement to the magnetic forces first, and avoids the constraint of the attractive levitation in replacing the repulsive levitation. Finally, we adopt the concept of relative place to build the measuring system. All of the performance of the improved framework is demonstrated in the experimental results.

Development of 6DOF Magnetic Levitation Stage for Lithography Tool

In this paper, a detail design of MAGLEV(MAGnetic LEVitation) stage is put into effect based on the concept that was persuaded in 1st paper, ”Development of 6DOF Magnetic Levitation Stage for Lithography Tool -Background and First Report-“, in that the limit of vacuum compatible air bearing was discussed. Because the proof of concept should be quickly required, local design such as material and component was changed from the initial concept. The key specification, control bandwidth, coupling between other axes, vibration transmissibility and positioning accuracy were evaluated and the concept was verified. The possibility of application to the EUVL(Extreme Ultra Violet Lithography tool) reticle stage is obtained by changing the material to high stiffness rate ceramics in control simulation.

Development of 6DOF Magnetic Levitation Stage for Lithography Tool

At first, I explain some key points and difficulty of lithography tool design, issues that should be overcome during the development and requirements for stages in lithography tool in this paper. Then, I have ascertained a limit of static-pressure air bearing with differential pumping mechanism for vacuum application, for instance EUVL(Extreme Ultra Violet Lithography tool) by manufacturing so-called the “vacuum compatible” 1-axis air bearing and verifying the performance by comparing with equivalent model simulation. Finally, one of MAGLEV(MAGnetic LEVitated) stage concepts is proposed instead of common AIRLEV(AIR LEVitated) stage by seriously considering a high throughput for mass production. I simultaneously contribute 2nd paper, “Development of 6DOF Magnetic Levitation Stage for Lithography Tool -Proof Of Concept (Second Report)-“ which is a sequel to this paper.