• Journal of KSNVE
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• v.8 no.4
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• pp.683-689
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• 1998

A control algorithm for multi-stage dampers is developed based on the mode skyhook control concept, and implemented on the full vehicle system environment. The test vehicle system is equipped with the real time controller, four-stage variable dampers and sensors. The real time controller is developed using a digital signal processor(DSP), digital I/O, A/D and D/A converters. The dampers are driven by the electromagnetic actuators of less than 20 msec response time. The sensors include accelerometers, relative displacement transducers, and steering wheel rate sensors, etc. Through a series of tests in laboratory and proving ground, the performance of the semi-active suspension system is evaluated and it is shown that the vehicle dynamic characteristics is improved with the developed damping system. Futhermore, the parameter tuning methods to enhance vehicle dynamic performance are propsoed.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.6
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• pp.573-580
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• 2009

In this paper, we develop a functional test model for magnetic bearing wheels. The functional test model is an electromagnetic levitation system that has three degree of freedom, which consists of one axial suspension from gravity and two axes gimbaling capability to small angels. A nonlinear controller with high-gain observers is proposed and the real-time experiment results show that the rotor is accurately levitated at the desired position and well-balanced, which is a suitable result for the potential use an magnetic bearing wheels. Also, the proposed scheme exhibits better performance when it is compared with the conventional PID control method.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.70-72
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• 1999

Actuator (chopper) and sensors failures resulting from electric shock and mechanical vibration generating by rail irregularities are the serious problem deteriorating the performance in the electromagnetic suspension systems. Thus, this paper proposes the reliable output feedback controller for the electromagnetic levitation systems against actuator, air-gap sensor and acceleration sensor failures. The designed controller is an extend version of a novel design technique which has the design method of the output feedback controller using dynamic compensator. The benefits of this scheme are demonstrated through the experimental results for the proposed controller against chopper, air-gap sensor and acceleration sensor failures of electromagnetic levitation system.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.228-230
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• 2005

In this paper, we address an active vibration control system, which suppresses the vibration engaged by magnetically levitated stage. The stage system consists of a levitating platen with four permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion via the vertical and horizontal forces. In the stage system, which represents the settling-time critical system, the motion of the platen vibrates mechanically. We designed an active vibration control system for suppressing vibration due to the stage moving. The command feedforward with inertial feedback algorithm is used for solving stage system's critical problems. The components of the active vibration control system are accelerometers for detecting stage tables's vibrations, a digital controller with high precise signal converters. and electromagnetic actuators.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.57-66
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• 1999

In this paper, we propose design methods of suspension controller for magnetically levitated system(MAGLEV). In this interior, the study of Electromagnetic Suspension(EMS) which has several advantages is chiefly achieved but, because the EMS has highly nonlinear and unstable property it is difficult to design the suspension controller maintaining stability and high performance. Here a Gain Scheduling Control(GSC) based on pole-placement scheme and on linear quadratic gaussian(LQG) design is separately presented. The several control performance is shown by simulation.

• Proceedings of the KSR Conference
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• 2006.11a
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• pp.171-180
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• 2006

The EMS system requires a very delicate suspension control to maintain constant air-gap between the magnet and the guide-way rail. To maintain a constant air-gap with attraction force, the EMS system dynamics is changed according to uncertainties and disturbances, and it also requires reliability against component failures. Since uncertainties and component failures are frequently caused in EMS system, it is very important to develop the robust and reliable control system. In this paper, we consider the design problem for robust and reliable controller in the presence of uncertainties and component failures.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.316-320
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• 1993

Electromagnetic suspension (E.M.S) type levitation system is studied in the control system design viewpoint. Dynamic characteristics in theoretical analysis as well as hardware implementation is considered. Open loop unstable, non-linear and timevarying characteristics are reviewed in the theoretcal section, while levitation control system for multi-vehicle train as well as magnet drive system is reviewed in the practical section. This paper suggests not only some well-known problem appearing in levitation control system design but also a subtle problem and solution candidates. But there exist many unmentioned problems wating for a smart problem solver.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.333-338
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• 1993

A feedback linearization controller for EMS system is implemented using DSP. In this paper, we show that given EMS system is input-state linearizable and satisfies some robustness condition. Also we derive feedback linearization controller for given system. Finally, some experiments are performed to demonstrate the performance of the proposed controller-especially, comparing this with the classical state feedback controller using linear perturbation.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.180-188
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• 2003

In the precision motion device, the frictional problem by mechanical friction causes serious effects on the system performance. Various researches have been executed to solve this problem, but classical fluid lubrication method has some disadvantages in precision motion under clean environment. Therefore, the magnetic bearing and contact-free systems have been focused on with its pollution-free characteristics. In this paper, we treat modeling and analysis of electromagnets not only for magnetic bearing but also fer contact-free electromagnetic actuators. Three types of electromagnet for various applications are modeled and analyzed by magnetic circuit theory and the validity is verified by experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2252-2257
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• 2003

In this paper, we develop the so-called functional test model for magnetic bearing reaction wheels. The functional test model has three degree of freedom, which consists of one axial suspension from gravity and the other two axes gimbaling capability to small angle, and does not include the motor. For the control of the functional test model, we derive the optimal electromagnetic forces based on the least squares method, and use the proportional-integral-derivative controller. Then, we develop a hardware setup, which mainly consists of the digital signal processor and the 12-bit analog-to-digital and digital-to-analog converters, and show the experimental results.