• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.1940-1942
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• 2001

Magnetic Levitation System(MLS) levitates a steel ball to the desired position in the gravity field using electromagnetic force. MLS consists of light sensor to measure the position of steel ball and an electromagnet to control the position of the ball, that composes a feedback control system. This work does not use a steel ball with constant mass but variable mass steel balls as magnetic levitation targets. Differential equation of electric circuit for electromagnet and motion equation of the movement of steel ball are derived for modeling nonlinear system, that will be linearized at the nominal operating point. We propose a digital control that can levitate a steel ball of which weight is not known for ED-4810 system. Algorithm for estimating ball weight and feedback control are implemented in digital scheme under pentium PC equiped with A/D and D/A converter, ACL-8112, using C-language. Simulation and experimental results are given to show the usefulness of the proposed controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.699-703
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• 1991

A magnetic levitation system with hybrid magnets, which is composed of permanent magnets and electromagnets, consumes less power than the conventional attraction type system. In this paper, we propose PID controller and PID-Fuzzy controller for hybrid magnet. We first present "constant gap" control technology with PID controller. Secondly, "zero power" control technology with PID-Fuzzy hybrid controller is presented.roller is presented.

• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.584-592
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• 2008

In this paper, we propose a new model of the magnetic control force exerted on the levitation object in magnetic levitation systems. The model assumes that the magnetic force is a function of the voltage applied to an electromagnet and the position of a levitation object. The function is not explicitly expressed but represented through a 2D lookup table constructed from the experimentally measured data. Unlike the conventional model that reveals only local characteristics of the magnetic force, the proposed model shows global characteristics satisfactorily. Specially devised measurement equipment is utilized in order to gather the data required for model construction. An experimental procedure to construct the model is presented. We apply the proposed model to designing a sliding mode controller for a lab-built magnetic system. The validity of the proposed model is illustrated by comparing the performances of the controller adopting the conventional model with that of the controller adopting the proposed model.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.944-949
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• 2017

Recently, the demand of maglev systems in the manufacturing industry for LCD and OLED display panels, which are required to be very clean and possess vacuum systems, has been increasing due to their characteristics such as being non-contact, noise free and eco-friendly. However, it is still a challenge to simultaneously control both the propulsion and levitation for their interactive effect difficult to be exactly measured. In this paper, we proposed a new tuning method for controlling the magnetic levitation force robustly against the levitation disturbance caused by a propulsion system, based on LQ servo optimal control. The disturbance torque of the LSM propulsion system is calculated through FEM analysis in such a way that the LQ servo controller is determined in order to minimize the effect of the disturbance. The robust performance of the proposed LQ servo control method for the in-track type magnetic levitation systems is demonstrated via simulations and experiments.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.345-350
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• 1993

This paper presents an on-line feedback error learning control algorithm for a magnetic levitation system. It will be shown that even in the case of abrupt changes of the system parameters and disturbanes, the control performance is still very satisfactory.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1191_1192
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• 2009

The objective of levitation control design is to stabilize a levitation system, or obtain certain transient response, bandwidth, and steady state error. An air gap signal from the each corner is important parameter to design levitation controller. A levitation controller using gap signals with measurement delay time can not make a expected performance. In this paper, a new air gap estimator to improve the performance of levitation controller is proposed. The estimated gap signal which has little measurement delay time is used as a feedback value in the levitation controller.

• 한국정밀공학회지
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• 제19권7호
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• pp.36-42
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• 2002

This paper presents two actuators for levitation using repulsions of permanent magnet and two magnetic levitation tables using the actuators. Here, one actuator for levitation consists of one fixed magnet and one moving magnet, and the other actuator consists of two fixed magnets and one moving magnet. The moving part of the magnetic levitation table contains the moving magnets. repulsive forces caused by the permanent magnets are linearized, and then the equation of motion of the moving part of the table is derived. Using the equation of motion, stability conditions of the moving part are deduced. The stability conditions are analyzed for positional relations of the moving magnets and the minimum number of active control required for stable system. As a result, in the each case of magnetic levitation tables, the requirements for stabilization are expressed by the positional relations and the number of the active controls.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.195-200
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• 1994

This paper presents a nonlinear adaptive control approach to a 4-point attraction magnetic levitation system using the local coordinates transformation and neural network. Based on local coordinates transformations, the magnetic levitation system can be represented in a state magnetic levitation system can be represented in a state space from of a 4-input 4-output. Neural networks which are defined in the new coordinates are used to learn the nonlinear functions of the system which are defined in the new coordinats also. The parameters of the neural networks are updated in an on-line manner according to an augmented tracking error. The simulation results are reported in this paper.

• Journal of Advanced Marine Engineering and Technology
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• 제27권7호
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• pp.862-871
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• 2003

In this paper, we addressed a modeling for the magnetic levitation stage. This planar magnetic levitator employs four permanent magnet liner motors. Each motor generates vertical force for suspension against gravity, as well as horizontal force for propulsion. Therefore. this stage can generate six degrees of freedom motion by the combination of forces. We derived a mechanical dynamics equation using Lagrangian method and electromechanical dynamics equation by using Co-energy method. Based on the derived dynamics, we can analyze the stage motion that is subject to the input currents and forces.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.426-431
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• 1997

In this paper, a sensorless realization method is proposed for the magnetic levitation system. Also we design the robust servo controller which based on the two degree-of-freedom-control theory and H$\sub$.inf./ control theory for the system. From time responses, we confirm that the proposed sensorless method can be applied the magnetic levitation system. Also the designed controller has the good disturbance rejection and the reference tracking performance.