• 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.553-557
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• 1994

We propose a design method that uses H$_{\infty}$ optimization method to suppress oscillation of a shaft between motor and load for high precision (0.001 % of reference input) position controls. PI speed control loop was introduced as a minor loop. Standard problem is used for the modeling of the system and Glover-Doyle's algorithm is used for the optimization in the H$_{\infty}$ space. Friction is considered to be an important factor that makes it difficult for the system to reach steady state in short time. In this paper, we propose a hybrid controller that includes PI speed feedback loop, which is expected to have a role to reject torque disturbance like friction.n.n.

• 전자공학회논문지SC
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• 제39권5호
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• pp.26-33
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• 2002

본 논문에서는 볼록 한계 불확실성(convex bounded uncertainty)을 가지는 이산시간 선형 시스템의 견실 $H_{\infty}$ 필터 설계 알고리듬을 제안한다. 다루고 있는 파라미터 불확실성은 폴리토프형(polytope type) 볼록 한계를 가지는 형태이다. 본 논문의 목적은 필터링 오차 시스템의 점근 안정성(asymptotic stability)과 변형한 성능지수의 유도 $L_2$ 노옴($L_2$ induced norm) 한계치를 해적적으로 제시하는 안정한 견실 $H_{\infty}$ 필터를 설계하는 것이다. 견실 $H_{\infty}$ 필터가 존재할 충분조건과 필터 설계 방법은 볼록 최적화 기법에 의하여 효과적으로 해를 구하는 선형행렬부등식 방법에 의하여 제시한다. 제안한 알고리듬의 타당성은 예제를 통하여 확인한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.344-347
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• 1995

The standard estimation and filtering theory are well known and has recently been incorporated with the H$_{\infty}$ optimization techniques where the parametrizations of all estimators and filters are utilized. The issue of reducing its order is always of interest. This paper presents a method for synthesizing low-order stable state estimators. The method presented in this paper is based on the utilization of a free parameter function contained in the parametrization of all state estimators. The results obtained in the paper are compared with standard results on low-order estimators. Both results are shown to be the same in a sense of its orders, but the approaches taken are largely different. It is also shown in the paper that the method can easily and directly be extended to the Kalman filters and the H$_{\infty}$ (sub)optimal filters. Consequently, the orders of all state estimators, Kalman filters, and H$_{\infty}$ filters are shown to be reduced down to the number of states minus the number of outputs, respectively.ly.

• International Journal of Precision Engineering and Manufacturing
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• 제1권2호
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• pp.24-34
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• 2000

In this paper we propose a controller design method, called Quasi-LQG/$H_{\infty}$/LTR for nonlinear servo systems with hard nonlinearities such as Coulomb friction, dead-zone. Introducing the RIDF method to model Coulomb friction and dead-zone, the statistically linearized system is built. Then, we consider $H_{\infty}$ performance constraint for the optimization of statistically linearized systems, by replacing a covariance Lyapunov equation into a modified Riccati equation of which solution leads to an upper bound of the LQG performance. As a result, the nonlinear correction term is included in coupled Riccati equation, which is generally very difficult to thave a numerical solution. To solve this problem, we use the modified loop shaping technique and show some analytic proofs on LTR condition. Finally, the Quasi-LQG/$H_{\infty}$/LTR controller for a nonlinear system is synthesized by inverse random input describing function techniques (ITIDF). It is shown that the proposed design method has a better performance robustness to the hard nonlinearity than LQG/$H_{\infty}$/LTR method via simulations and experiments for the timing-belt driving servo system that contains the Coulomb friction and dead-zone.

• 한국정보통신학회논문지
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• 제5권6호
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• pp.1089-1093
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• 2001

다중비 필터뱅크의 합성 필터 선계 문제에 H$\infty$ 제어기법을 적용한다. 순수한 시간 지연 시스템을 기준 모델로 설정하여 이 지연 시스템과 다중비 필터 뱅크와의 오차 시스템을 고려한다. 설계 하고자 하는 합성 필터는 오차 시스템의 ι$_2$-유도된 노름을 최소화하도록 설계한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2161-2163
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• 2004

This paper focuses on congestion control for ATM network with uncertain time-variant delays. The time-variant delays can be distinguished into two distinct components. The first one that is represented by time-variant queueing delays in the intermediate switches is occurred in the return paths of RM cells. The next one is a forward path delay. It is solved by the VBR Model which quantifies the data propagation from the sources to the switch. Robust $H_{\infty}$ control is studied for solving congestion problem with norm-bounded time-varying uncertain parameters. The suitable robust $H_{\infty}$ controller is obtained from the solution of a convex optimization problem including terms of LMIs.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.269-269
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• 2000

This paper presents a predictive control with H$_{\infty}$ suboptimal performance which is robust to disturbances and has a guaranteed stability. In order to derive the control law conveniently, state-space based approach, where the state variable is involved explicitly in the controller design and implementation is allowed. So an input-output model is converted to an equivalent observable canonical state-space form. The suggested control guarantees the norm bounded system output values from disturbances. A systematic way using the LMI method is presented to obtain appropriate parameters for Quadratic stability condition and optimization problem.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.125-127
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• 2001

In this paper, a robust $H_{\infty}$ optimal design problem under a structure-specified PSS is investigated for power systems with parameter variation and disturbance uncertainties. Immune algorithm is employed for optimization method of PSS parameter. It is shown that the proposed $H_{\infty}$-PSS tuned using immune algorithm is more robust than conventional PSS.

• 대한전기학회논문지:전력기술부문A
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• 제52권1호
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• pp.1-8
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• 2003

This paper presents a novel application method of H$_{\infty}$ optimization method to the design of Power System Stabilizer(PSS) and experimental results through hardware simulator. The approach is focused on decision of performance index and selection strategy of weighting functions together with its tuning for direct design. As the Purpose of the PSS is to increase system damping at very narrow frequency band, weighting functions are determined differently from the case of general servo system control. The designed PSS was confirmed through experiments on a hardware simulator.

• 한국지능시스템학회논문지
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• 제14권5호
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• pp.557-562
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• 2004

이 연구는 T-S 퍼지시스템으로 모델 되는 비선형 시스템의 견실한 혼합 ${H_2}/{H_{\infty}}$ 필터 설계문제를 취급한다. 플랜트에 포함된 다양한 종류의 불확실성을 취급하기 위하여 적분 2차 제약조건을 사용하였다. 필터 설계문제의 해가 존재할 충분조건을 볼록 최적화 기법을 사용하여 효과적으로 풀 수 있는 선형 행렬 부등식의 형태로 제시한다. 제시된 방법을 예시하기 위해서 수치 예를 보여준다.