• 제어로봇시스템학회:학술대회논문집
• /
• 1986.10a
• /
• pp.275-280
• /
• 1986

본 연구는 LQR을 Robust하게 설계하는 방법을 다루었다. Unstructured Perturbation에 대응하기 좋으며 쉽게 다룰 수 있는 주파수 응답형 LQR criteria 선정법과, LQR의 변형으로서 Structured Perturbation에 대하여 유효한 Performance Criteria Insensitive Control을 제시하고 효과를 살펴보았다.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.482-485
• /
• 1993

This paper deals with structured singular value and mixed sensitivity problem for robust performance. We derive the sufficient condition that mixed sensitivity problem satisfies structured singular value in robust performance problem. And we show the bound of perturbation between structured singular value and norm of mixed sensitivity functions.

• Journal of Institute of Control, Robotics and Systems
• /
• v.1 no.2
• /
• pp.78-82
• /
• 1995

In this paper, we consider the robustness analysis problem in state space models with linear time invariant perturbations. Based upon the discrete-time Lyapunov approach, sufficient conditions are derived for the eigenvalues of perturbed matrix to be located in a circle, and robustness bounds on perturbations are obtained. Spaecially, for the case of a diagonalizable hermitian matrix the bound is given in terms of the nominal matrix without the solution of Lyapunov equation. This robustness analysis takes account not only of stability robustness but also of certain types of performance robustness. For two perturbation classes resulting bounds are shown to be improved over the existing ones. Examples given include comparison of the proposed analysis method with existing one.

• 제어로봇시스템학회:학술대회논문집
• /
• 1995.10a
• /
• pp.420-423
• /
• 1995

The stability of system is one of the important aspects and to judge system's stability is another complicated problem. Previously, new technique derived from relaxing Lyapunov conditions has been already introduced and in this paper, this proposed technique applies to the practical dynamic systems. This utility of numerical procedures prove the comparable improvements of the estimation of robustness for dynamic systems having structured (bounded) perturbations.

• Journal of Institute of Control, Robotics and Systems
• /
• v.21 no.1
• /
• pp.34-39
• /
• 2015

In this paper, a finite impulse response (FIR) filter is proposed for discrete-time nonlinear systems. The proposed filter is designed by combining the estimate of the perturbation state and nominal state. The perturbation state is estimated by adapting the optimal time-varying FIR filter for the linearized perturbation model and the nominal state is directly obtained from the nonlinear nominal trajectory model. Since the FIR structured estimators use the finite horizon information on the most recent time interval, the proposed extended FIR filter satisfies the bounded input/bounded output (BIBO) stability, which can't be obtained from infinite impulse response (IIR) estimators. Thus, it can be expected that the proposed extended FIR filter is more robust than IIR structured estimators such as an extended Kalman filter for the round-of errors and the uncertainties from unknown initial states and uncertain system model parameters. The simulation results show that the proposed filter has better performance than the extended Kalman filter (EKF) in both robustness and fast convergency.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10a
• /
• pp.850-856
• /
• 1992

The problem of robust control of a underwater vehicle subject to variation of a real parameter and velocity is considered. The controller set which stabilized perturbed plant is chosen using numerical gradient method and the controller is used for nominal performance and robust performance. Simulation results are presented to show that the precise montion control of the controller is accomplished under perturbation in the system.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.4
• /
• pp.316-325
• /
• 1989

This paper is concerned with robust stabilization of single input or single output systems. Based on the region of non-destabilizing perturbations some approaches to design which allow the given of structured perturbation of plant parameters and their gradient optimization are given. These algorithms iteratively enlarge the stability hypershere in plant parameter space and can be used to design a controller to stabilize a plant subject to given ranges of parameter excursions.

• Journal of Institute of Control, Robotics and Systems
• /
• v.3 no.1
• /
• pp.17-22
• /
• 1997

The stability robustness problem of linear discrete-time systems with time-varying perturbations is considered. By using Lyapunov direct method, the perturbation bounds for guaranteeing the quadratic stability of the uncertain systems are derived. In the previous results, the perturbation bounds are derived by the quadratic equation stemmed from Lyapunov method. In this paper, the bounds are obtained by a numerical optimization technique. Linear matrix inequalities are proposed to compute the perturbation bounds. It is demonstrated that the suggested bound is less conservative for the uncertain systems with unstructured perturbations and seems to be maximal in many examples. Furthermore, the suggested bound is shown to be maximal for the special classes of structured perturbations.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.4 s.175
• /
• pp.1065-1074
• /
• 2000

A robust nonlinear $H_2$/$H_{\infty}$ control method for a parallel inverted pendulum with structured perturbation and dry friction is proposed. By the random input describing function techniques, the nonlinear dry friction is approximated into the quasi-linear system. Introducing the quadratic robustness theorem, the robust $H_2$/$H_{\infty}$ control system is constructed for the quasi-linear perturbed system. But it is difficult to design a controller due to the nonlinear correction term in Riccati equation. With some transformations on the Riccati equation containing nonlinear correction term, the design of the robust nonlinear controller can be done easily. Hence when the stiffness and mass of the parallel inverted pendulum vary in certain ranges, the proposed control scheme has the robustness for both the structured perturbation and dry friction. The results of computer simulation show the effectiveness of our proposed control method.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.3
• /
• pp.300-310
• /
• 1992

This paper deals with the problem of robust pole-assignment control for linear systems with structured uncertainty. It considers two cases whose colsed-loop characteristic equations are presented as a family of interval polynomial and polytopic polynomial family respectively. We propose a method of finding the pole-placement region in which the fixed gain controller guarantees the required damping ratio and stability margin despite parameter perturbation. Some results of Kharitonov like stability and two kinds of transformations are included. As an illustrative example, we show that the proposed method can apply effectivly to the single magnet levitation system including some uncertainties (mass, inductance etc.).