• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.307-314
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• 2018

In this paper, analytical modeling of lift and drag forces in permanent magnet electrodynamic suspension systems (PM EDSs) are presented. After studying the impacts of PM dimensions on the permanent magnetic field and developed lift force, it is indicated that there is an optimum PM length in a specified thickness for a maximum lift force. Therefore, the optimum PM length for achieving maximum lift force is obtained. Afterward, an objective design optimization is proposed to increase the lift force and to decrease the material cost of the system by using Genetic Algorithm. The results confirm that the required values of the lift force can be achieved; while, reducing the system material cost. Finite Element Analysis (FEA) and experimental tests are carried out to evaluate the effectiveness of the PM EDS system model and the proposed optimization method. Finally, a number of design guidelines are extracted.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.414-424
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• 2017

This paper introduces an experimental device which can measure accurate aerodynamic forces without support interference in wide experimental region for wind tunnel test of micro aerial vehicles (MAVs). A stereo pattern recognition (SPR) method was introduced to a magnetic suspension and balance system (MSBS), which can eliminate support interference by levitating the experimental model, to establish wider experimental region; thereby MSBS-SPR integrated system was developed. The SPR method is non-contact, highly accurate three-dimensional position measurement method providing wide measurement range. To evaluate the system performance, a series of performance evaluations including SPR system measurement accuracy and 6 degrees of freedom (DOFs) position/attitude control of the MAV model were conducted. This newly developed system could control the MAV model rapidly and accurately within almost 60mm for translational DOFs and 40deg for rotational DOFs inside of $300{\times}300mm$ test section. In addition, a static wind tunnel test was conducted to verify the aerodynamic force measurement capability. It turned out that this system could accurately measure the aerodynamic forces in low Reynolds number, even for the weak forces which were hard to measure using typical balance system, without making any mechanical contact with the MAV model.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.154-157
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• 1995

A magnetic levitation control system is nonlinear and very unstable. Thus there should be a stabilizing compensation network and a feedback path. Due to the levitation control a noncontact photoresistor sensor is generally used. One photocell provides a certain amount of variation in length by the ball shadow casted on the cell surface. Furthermore at the boundary of the cell, the linearity of sensitivity deteriorates severely. To overcome the constraints of the length and linearity, an efficient sensor array is deviced and applied in the feedback path of a large-gap magnetic levitation control system. A number of CdS photocells and a summing circuit of the sensor output signals are used for a sensor array. The levitation length of a ball and the transient performances are main objectives of the large-gap suspension system using the sensor array.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.463-471
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• 2013

This paper presents design and control of electronic control suspension(ECS) equipped with controllable magnetorheological(MR) damper for passenger vehicle. In order to achieve this goal, a cylindrical type MR fluid damper that satisfies design specification of a middle-sized commercial passenger vehicle is proposed. After manufacturing the MR damper with design parameters, their field-dependent damping forces are experimentally evaluated and compared with those of a conventional damper. A quarter-vehicle MR ECS system consisting of sprung mass, spring, tire, controller and the MR damper is established in order to investigate the ride comfort performances. On the basis of the governing equation of motion of the suspension system, five control strategies(soft, hard, comfort, sport and optimal mode) are formulated. The proposed control strategies are then experimentally realized with the quarter-vehicle MR ECS system. Control performances such as vertical acceleration of the car body and tire deflection are evaluated in frequency domains on random road condition. In addition, performance comparison of WRMS(weighted root mean square) of the quarter-vehicle MR ECS system on random road are undertaken in order to investigate ride comfort characteristics.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.6
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• pp.454-461
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• 2000

Electrostatic suspension offers an advantage of directly suspending various materials such as conductive materials, semiconductors and dielectric materials without any mechanical contacts. This is a specific feature compared with electromagnetic suspension which can suspend only ferro-magnetic material. In general, the electrostatic suspension systems require position sensors for stabilizing the suspended object. Therefore, a lot of displacement sensors and a switching circuit are required for moving the object through a long distance. In order to circumvent this problem, this paper proposes a self-sensing method which can provide the gap displacement between electrodes and suspended object without external sensors. Moreover a simple on-off controller is presented for stabilization. Experimental validation of the proposed scheme has been performed through the successful levitation of a 4-inch silicon wafer.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1045-1051
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• 2016

This paper introduces a new optimal design method using a bacterial survival strategies for a ectromagnet of Maglev transportation vehicle. Usually, an electromagnetic suspension which has more advantages than electro dynamic suspension is used in Maglev systems. However, the structural constraints must be considered in the optimal design of an electromagnet for electromagnetic suspend system. In this paper, the optimal design method of a electromagnet based on a bacterial survival strategies optimization algorithm to design the electromagnet satisfying the structural constraints. The effectiveness of the proposed method was verified by Matlab simulations and the simulation results show that the proposed method is more efficient than conventional methods.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.92-101
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• 2010

Recently, the magnetic bearings which have many advantages such as no noise, less mechanical friction are widely applied to the suspension of rotors on the rotary machineries. However, the magnetic bearing system is inherently unstable, nonlinear and MIMO(multi-input-multi-output) system as well. In this paper, we design a state feedback controller using linear matrix inequality(LMI) to the multi-objective synthesis, for the magnetic bearing system with integral type servo system. The design objectives include $H_{\infty}$ performance, asymptotic disturbance rejection, and time-domain constraints on the closed-loop pole location. The results of computer simulation show the validity of the designed controller.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.1
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• pp.29-37
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• 2019

A new permanent magnet biased hybrid maglev actuator is developed. Compared to the classical hybrid maglev actuators, the new maglev has unique flux paths such that bias fluxes are separated with control flux paths. The control flux paths have minimum reluctances only developed by air gaps, so the currents to produce control fluxes can be minimized. The consumed power to operate this maglev system can also be minimized. The gravity load can be compensated with the static magnetic forces developed by the permanent magnet bias fluxes while external disturbances are controlled with the bidirectional AC magnetic forces developed by control fluxes by currents. 1-D circuit model is developed for this model such that the flux densities and magnetic forces are extensively analyzed. 3-D finite element model is also developed to analyze the performances of the maglev actuator.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.11
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• pp.494-502
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• 2002

In this paper, a suspension control of a magnetic levitation(MagLev) system with flexible rail is designed and presented. The numerical modelling for the electromagnetic system to be controlled as a target plant is carried out. And dome kinds of the hardware system including CPU board, AD board, DA board, sensors, and switching power amplifier are described. Using the derived model, the stabilizing controllers, such as PID and $H_{\infty}$ controller, for the MagLev system are designed using the MATLAB toolbox. The designed controllers are validated by some experimental results as well as numerical simulations. So it is shown that $H_{\infty}$ controller can give the better performance for the plant with flexible modes than PID controller.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.37-41
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• 2008

Superconducting Electrodynamic suspension(EDS) system is generated by the interaction between the magnetic field made by the induced the eddy current in the ground conductor and the moving magnetic field made by onboard superconducting magnet. The levitation force of EDS system, which is proportional to the strength of the moving magnetic field, becomes saturated according to the increase of the velocity. Especially, the levitation force is influenced by the structure of HTS magnet and ground magnet. This paper deals with the optimal design condition for the HTS levitation magnet. The 3-D numerical analysis with FEM was used to find the distribution of the magnetic field, the optimal coil structure, and the calculation of the levitation force.