• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.106-109
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• 1993

A new VSC scheme, OFVSC(Output Feedback Variable Structure Controller), is proposed by consisting of servo compensator and output feedback VSC with dynamic switching function. The servo compensator which is designed for output variable enhances the robustness for all the types of disturbances, and makes effective tracking is possible without using error dynamics which is usually used in conventional VSC. The proposed OFVSC is applied to the practical design of a robust DC servo control system and the control performances are evaluated through theoretical analysis and simulations.

• 융합신호처리학회논문지
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• 제5권3호
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• pp.210-215
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• 2004

교류 서보전동기 동적 모델은 비선형이고 2차 저항이 변동영향이 많다. 이러한 복잡한 제어는 견실제어가 요구된다. 이러한 시스템의 동특성은 슬라이딩 모드제어를 사용함으로 파라미터나 외란 변동에 대하여 견실성을 달성할 수 있다. 본 논문은 교류 서보전동기에 의한 위치제어에 슬라이딩 모드 제어의 적용을 나타내었다. 제어방법이 유도되고 제어시스템이 설계되었다. 교류 서보전동기의 견실제어를 위해 외부 부하 파라미터에 기초한 설계방법이 제안되었다. 제안된 제어방법은 가변구조 제어기와 슬립주파수형 벡터제어에 기초하여 주어졌다. 시뮬레이션 결과는 관성모우먼트, 점성마찰 및 부하외란 변동에 결실함을 나타내었고 슬라이딩 모드를 적용한 제안된 설계방법이 유용한 것을 구명한다.

• 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.

• 소음진동
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• 제8권3호
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• pp.533-541
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• 1998

Recently, optical disk drives are increasingly demanded to have higher speed as well as high information density, especially for applications like CD ROM drives. To this end, improvement of their optical pickup structure and control is recognized the very challenging issue. In this paper, the pickup is first analytically modelled in a plane to describe its coupled auto-focusing and auto-tracking motions. Subsequently, the model is linearized and combined with actuator dynamics for the auto-focusing system. With its unmeasurable parameters being estimated based on experimental data, an approximate I-DOF linear model is obtained neglecting the coupling term. To design the high speed and robust positional servo controller realistic design specifications are addressed, and H control method is employed based on the approximate model. Finally, taking the pickup in a commerical high speed CD ROM drive as an example performance of the designed controller is verified through realtime experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.726-728
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• 1995

A servo control algorithm robust under disturbance and reference change is developed using the self tuning control method based on the concept of the least distribution control. Also, the design algorithm incorporates the concepts of the well known internal model principle and the annihilator polynomial. In order to evaluate the effectiveness of the method, MAGLEV (Magnetic Levitation) system is used and the position control experiment for reference changes and disturbances of step type is done.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.795-797
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• 1998

This paper suggests a design method of the optimal PD control system having robust performance. This PD control system is designed by applying genetic algorithm(GA) with reference model to the optimal determination of proportional(P) gain and derivative(D) gain that are given by PD servo controller. These proportional and derivative gains are simultaneously optimized in the search domain guaranteeing the robust performance of closed-loop system. This PD control system is applied to the fuel-injection control system of diesel engine and compared with ${\mu}$ -synthesis control system for robust performance. The effectiveness of this PD control system is verified by computer simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.10-14
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• 1990

Variable Structure System(VSS) la being extended to a new control system of ac servo machines for its merits of simple mechanism and robustness. This paper has studied about applying VSS to position control for brushless servo motor. But VSS has the chattering problem of control input. This chattering phenomenon cause acoustic noises, torque ripple and increase harmonics of the current. One of the useful way to eliminate this defect of VSS, linearlizing the switching function is discussed here. Though the conventional method of linearizing the switching function diminishes the chattering, it may degrade the robustness of the system. In this paper, new linearized switching function which shows robust performance to the parametric variation and reduces chattering simultaneously is introduced and assured by simulation.

• 전력전자학회논문지
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• 제24권1호
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• pp.49-55
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• 2019

This study proposes a robust control of a fin position servo system using the H-infinity loop-shaping method. The fin position control system has a proportional (P) position controller and a proportional-integral (PI) controller. In this work, the position control loop requires a wide bandwidth. No current control loop exists due to the compact design of the system. Hence, the controller parameters are difficult to determine using the traditional cascade design method. The $H_{\infty}$ controller design method is used to design the controller's gain to achieve good performance and robustness. First, the transfer function of the system, which can be divided into tunable and fixed parts, is derived. The tunable part includes the position P controller and speed PI controller. The fixed part includes the rest of the system. Second, the optimized controller parameters are calculated using Matlab $H_{\infty}$ controller design program. Finally, the system with optimized controller is tested by simulation and experiment. The control performance is satisfactory, and the $H_{\infty}$ controller design method is proven to be valid.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.541-543
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• 1998

Generally, PI control is simple and easy to implement and gains of PI control are determined by specifying a dynamics of the servo driver system. However, the gain-tuning is so difficult that it is relied on an expert's effort. This paper presents a gain auto-tuning method for PI controllers based on a fuzzy inference mechanism. First, the proposed fuzzy inference system identifies a system moment of inertia and adjusts control gains by using the difference in speed responses between a real plant and a reference model. Second, this paper proposes an improved fuzzy PI controller. To reduce the speed overshoot, we adapt a control method that selects a proper PI gains with respect to the load inertia variation. To prove the validity of the proposed gain tuning algorithm and the feasibility of the servo drive, a high performance servo drive will be implemented by DSP(TMS320C31) and intelligent power module (IPM). The proposed controller is applied to the speed control of the 300W AC servo motor. Some simulations and experimental results show that the proposed fuzzy PI controller is more robust than the conventional PI controller against the load inertia variation.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.422-428
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• 2002

In this study, actuator, sensor, guide, power transmission element and control method are considered for ultra-precision positioning apparatus. Through previous process, single plane X-Y stage with ultra-precision positioning is manufactured. Global stage for the purpose of materialization with robust system, is combined by using AC servo motor and ball screw and rolling guide. And ultra-precision positioning system is developed by micro stage with elastic hinge type and piezo element. global servo and micro servo for the purpose of materialization positioning accuracy with nm(nanometer) are controlled simultaneously by using incremental encoder and laser interferometer as displacement measurement sensor. Through previous process, ultra-precision positioning system (100mm stroke and ${\pm}$ 10nm positioning accuracy) with single plane X-Y stage are materialized.