• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.342-347
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• 1995

Loop shaping $H_{\infty}$control with normalized coprime factorization was applied to a servo-motor driven high-speed powitioning system. The high-gain controller was designed to attenuate the postion errors caused byfriction effects and extermal disturbances. The non-existence of limit cycle was analyzed, though there is actuator saturation. The designed $H_{\infty}$control system was experimently tested in a rotary index table. Results showed its effectiveness to improve postion accuracy with out any compensation scheme for friction, and robustness to model perturbation and external disturbances.ces.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.423-425
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• 1998

Resonance effects and nonlinear frictions which generate many problems in control system exist in almost all the servo system. therefore, In this paper, the design procedure which employs $H_{\infty}$ control theory after augmenting with two integrators is proposed to track the ramp input. Limit cycles are unavoidable by the effect of interaction between two integrators and Coulomb friction in these system. The describing function is used to check the limit cycles and decide the coefficients of two integrators to minimize the effect of the limit cycles.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1897-1900
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• 2004

In recent years, a lot of industrial equipments have serial communication channel such as FieldBus (CAN, Profibus, etc.) or Ethernet that provides real time communication between industrial equipments. Theses applications include gantry crane, robot, chip mounter, etc.. In this paper, we discuss the synchronization technique for networked multi-motor systems where controllers (commercial servo amps) are distributed and interconnected by CAN (Controller Area Networks). We first describe the equivalent model for the individual servo-amp and motor using the frequency response. We design the $H{\infty}$ controller for motion synchronization. Finally, the synchronization technique using the equivalent model and the $H{\infty}$ controller is verified by the simulation and the experiment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.306-312
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• 1996

The performance of the failure detection algorithm may be greatly influenced by the model uncertainty. It is very important to design a robust failure detection system to the model uncertainty. In this paper, a design procedure to generate failure detection algorithm is proposed. The design procedure suggested is based on the concept of the‘threshold selector［1］’. The H$\infty$ control algorithm is used to derive a threshold selector which is robust to the model uncertainty, The threshold selector derived can be used to develop a failure detection system together with the weighted cumulative sum algorithm［3］. Computer simulation study showed that the failure detection system designed for an ISA(Integrated Servo Actuator) system by using the proposed method is robust to the model uncertainty.

• International Journal of Control, Automation, and Systems
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• 제1권1호
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• pp.83-92
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• 2003

The outdoor antenna servo system is subject to has significant torque disturbances from wind pressures and gusts on the antenna structures, as well as bearing and aerodynamic frictions. This control system should provide a sharp directivity in spite of the environmental disturbances and internal uncertainties. Therefore, the implementation of a real-time controller is necessary for the precise generation of the reference signal and robust tracking performance. In this paper, the discrete-time controller for the quick tracking of a target communication satellite is designed by applying the sampled-data $H_{\infty}$ control theory along with the reference signal generated by an improved conventional step-tracking algorithm. The sampled-data $H_{\infty}$controller demonstrates superior robustness for the longer sampling period when compared with a simple PID controller.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2001년도 하계 학술대회 논문집(KISPS SUMMER CONFERENCE 2001
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• pp.129-132
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• 2001

본 논문은 3 관성시스템의 진동억제를 위한 강인한(robust) 제어기의 설계법을 제안하고 이를 simulation 을 통하여 확인하는데 있다. 일반적으로 관성 시스템의 제어 문제는 결국. 시스템 자체에서 발생하는 진동을 최대한 억제하면서 빠른 시간에 원하는 위치에 출력을 가져가는 데 있다. 이 경우 문제로 되는 것은 시스템의 모델링 과정에서 발생하는 플랜트의 불확실성과 parameter 변동이다. 여기서는 일반적인 강인한 제어기 설계 이론의 하나인 $H_{\infty}$ 이론이 가지는 단점인 제어기의 보수성을 극복하면서, 동시에 출력의 과도응답특성을 개선하기 위한 방법으로 $H_2$ 이론을 병용하고 이를 LMI 이론으로 해석하였다. 이 과정에서 3 관성시스템에 LMI 이론을 적용하기 위한 일반화플랜트의 모형을 제시하고 이것의 유효성을, 모델의 불확실성과 parameter변동을 동시에 고려한 simulation을 통하여 확인하였다.

• 한국군사과학기술학회지
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• 제4권1호
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• pp.73-82
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• 2001

In this Paper, slack is computed from a comparision of the cable pay out rate and the ship ground speed in accordance with laying conditions, and the speed controller of the cable engine based on an $H^{\infty}$ servo control is designed for adjusting the cable engine in order to lay a desired amount of slack. The controller is designed to have the robust tracking property of the cable engine under disturbances. The performance of the designed controller is evaluated by computer simulation, and, consequently, a feasibility study for laying the submarine cable stably is done through analyzing simulation results.

• 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.455-460
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• 1994

This paper presents a simple methodology for reducing the order of H$_{\infty}$ controllers in the mixed sensitivity control problems. The key point of this methodology is to transform the generalized plant expression to new one, where the control object and the weighting functions for the sensitivity function may have some poles on the imaginary axis. So that, this methodology makes it possible to use the standard method to solve the general H$_{\infty}$ design problems about the mixed sensitivity problems, even for a servo system or a oscillatory system. We derive that the order of H$_{\infty}$ controllers designed by this methodology may be reduced to n$_{p}$ where n$_{p}$ is the order of the denominator of the control object. It is clear that n$_{p}$ is lower than n$_{p}$ + n$_{s}$, which is the order of H$_{\infty}$ controllers obtained by the ordinary H$_{\infty}$ design method up to now, where n$_{s}$ is the order of the denominator of the weighting function for sensitivity. Finally, a numerical example is given to illustrate the results..lts.ts..lts.lts.

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.847-858
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• 2001

This paper considers the control model identification and H(sub)$\infty$ controller design for a tandem cold mill (TCM). In order to improve the performance of the existing automatic gauge control (AGC) system based on the Taylor linearized model of the TCM, a new mathematical model that can complement the Taylor linearized model is constructed by using the N4SID algorithm based on subspace method and the least squares algorithm based on ARX model. It is shown that the identified model had dynamic characteristics of the TCM than the existing Taylor linearized model. The H(sub)$\infty$ controller is designed to have robust stability to the system parameters variation, disturbance attenuation and robust tracking capability to the set-up value of strip thickness. The H(sub)$\infty$ servo problem is formulated and it is solved by using LMI (linear matrix inequality) techniques. Simulation results demonstrate the usefulness and applicability of the proposed H(sub)$\infty$ controller.

• Journal of Advanced Marine Engineering and Technology
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• 제19권3호
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• pp.84-90
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• 1995

The magnetic levitation system has great advantages, such as little friction, no lubrication no noise and so on. The magnetic levitation system need a stabilizing controller because it is a unstable system in natural. This paper presents the robust stabilizing controller design of the magnetic levitation system. The controller which is designed in this paper by $H_{infty}$ control theory is robust servo controller which has zero offset in spite of the model uncertainties. The validity of controller was investigater through the response simulation. In the future, we will use the result of this study at the actual magnetic levitation system.