• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.38-46
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• 2002

A new semi-continuous sliding mode control is proposed for electromagnetic suspension systems. The control input is derived from the reaching law and the Lyapunov stability criteria, which is composed of continuous terms and low switching term. It has a low switching gain and chattering fee characteristics. It is shown by the computer simulation that the proposed control has good tracking performance and robustness compared with the classical sliding mode control.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.165-171
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• 1998

An axial electromagnetic levitation system using attractive force is a highly nonlinear system due to the nonlinearity of materials, variable air gap and flux density. To control the levitating system with large air gap, a conventional PID control based on the linear model is not satisfactory to obtain the desired performance and the position tracking control of the sinusoidal motion by simulation results. Thus, sliding mode control(SMC) based on the input-output linearization is suggested and evaluated by simulation and experimental approaches. Usefulness of the SMC to this system is conformed experimentally. If the expected variation of added mass can be included in the gain conditions and the model, the position control performance of the electromagnetic levitation system with large air gap will be improved with robustness.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.158-162
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• 2004

The magnetic levitator is the device which can float a magnetic material at the midair by electromagnetic force and it's principle can be applied to the high speed magnetic bearing or magnetic levitation train. There are many difficulties to control, because the magnetic levitator is basically a nonlinear and unstable system. In this paper, this system is modeled assuming that it is a linear system nearby an operating point, and a proportional and derivative(PD) position controller is designed to carry out the variable position control. The performance of position control response is shown through simulation and experiment. A prototype magnetic levitator is constructed using PWM converter and DSP(Digital Signal Processor) based control board.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.731-737
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• 2012

In the present study, a feasibility study on an innovative satellite attitude control actuator is performed. The actuator is specially designed to generate the reaction torque in an arbitrary axis, so that a satellite attitude can be controlled by using itself. It consists of a spherical flywheel and electromagnets for levitation and rotation control of the ball. As the earlier study, a rotating performance test on the spherical actuator is conducted in a single rotating axis and vertical levitation condition. From the test results, it can be confirmed that the maximum speed and torque of the innovative device are 7,200rpm and 0.7Nm, respectively. Using a velocity-voltage characteristic curve of the spherical motor, an open-loop control (V/f constant control) is performed, and the test results show excellent control performance in acceleration and deceleration phases.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1990.06a
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• pp.572-575
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• 1990

• 기계와재료
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• v.9 no.2 s.32
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• pp.108-120
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• 1997

• KIPE Magazine
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• v.26 no.3
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• pp.53-59
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• 2021

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.119-120
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• 2015

본 논문은 학생 캡스톤디자인 작품제작의 결과를 정리한 것으로 MCU와 적외선 거리센서를 이용하여 공의 수평위치를 측정하고 이에 따라 양단 전자석의 강도를 조절하여 공이 중앙에 위치하도록 자동으로 제어하는 볼 밸런서의 구현방법에 대해 소개한다. 탁구공의 위치를 적외선 거리센서로 측정하고 MCU에 PID 제어기 기반의 자동제어 알고리즘을 구현하여 전자석의 강도를 PWM 제어함으로써 탁구공이 중앙에 위치하도록 자동으로 제어한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1559-1565
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• 2013

This study aims to investigate the dynamic interaction characteristics between Maglev vehicles and an elevated guideway. A more detailed model for the dynamic interaction of the vehicle/guideway is proposed. The proposed model incorporates a 3D full vehicle model based on prototyping, flexible guideway by a modal superposition method, and levitation electromagnets including the feedback controller into an integrated model. The proposed model was applied to an urban transit Maglev developed for a commercial application to analyze the dynamic response of the vehicle and guideway, and the effect of the surface roughness of the rail, mid-span guideway deflections, and air gap variations are then investigated from the numerical simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.794-801
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• 2017

When a radial wheel is placed so as to partially overlap a conductive plate and rotated, a lift force is generated on the wheel, a thrust force along the edge, and a lateral force which tends to reduce the overlap region. When several of these wheels are combined, it is possible to realize a system in which the stability of the remaining axes is ensured, except in the traveling direction. To validate the overall characteristics of the multi-wheel system, we propose a transfer system levitated magnetically using radial electrodynamic wheels. The proposed system is floated and propelled by four wheels and arranged in a structure that allows the thrusts generated by the front and rear wheels to offset each other. The dynamic stability of the wheel and the effect of the pole number on the three-axial forces are analyzed by the finite element method. At this time, the thrust and levitation force are strongly coupled, and the only factor affecting them is the wheel rotation speed. Therefore, in order to control these two forces independently, we make use of the fact that the ratio of the thrust to the levitation force is proportional to the velocity and is independent of the size of the gap. The in-plane and out-of-plane motion control of the system is achieved by this control method and compared with the simulation results. The experimental results show that the coupled degrees of freedom can be effectively controlled by the wheel speed alone.