• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.68.3-68
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• 2001

We describe the looper controller design for a hot strip mill. The looper is to control the strip tension which influences on the width of the strip. It is very important to control the looper control of the hot strip mill, but difficult to control the looper, because there exists mutual interaction among strip gauge, looper angle, and strip tension. In this paper, we present the modeling for the looper of a hot strip mill to control the tension of the strip and suggest a eigenstructure assignment method. The eigenstructure assignment is useful tool that allows the designer to satisfy damping, settling time, and mode decoupling specifications directly by choosing eigenvalue and eigenvectors. Desired eigenvalue and eigenvector are chosen to satisfy the desired responses.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.499-504
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• 2000

Since large space structures(LSS) such as a space station, a solar power station satellite, etc., are theoretically distributed parameter and infinite-dimensional system, they have to be modeled into large finite-dimensional systems for control system design. Besides, there are fundamental problems in active vibration control of the large flexible structures. For example, a modeled large finite-dimensional system must be controlled with a much smaller dimensional controller. This causes the spillover phenomenon which degrades the control performances and reduces the stability margin. Furthermore, it may destabilize the entire feedback control system. In this paper, we proposed a novel control method for spillover suppression in the control of large flexible structures by using eigenstructure assignment. Its effectiveness in spillover suppression is investigated and verified by the numerical experiments using an example of the simply supported flexible beam which is modeled to have four controlled modes and eight uncontrolled modes.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.226-231
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• 2008

In this paper, we propose novel eigenstructure assignment method in full-state feedback for linear time-invariant MIMO system such that directions of some left eigenvectors are exactly assigned to the desired directions. It is required to consider the direction of left eigenvector in designing eigenstructure of closed-loop system, because the direction of left eigenvector has influence over excitation by associated input variables in time-domain response. Exact direction of a left eigenvector can be achieved by assigning proper right eigenvector set satisfying the conditions of the presented theorem based on Moore's theorem and the orthogonality of left and right eigenvector. The right eigenvector should reside in the subspace given by the desired eigenvalue, which restrict a number of designable left eigenvector. For the two cases in which desired eigenvalues are all real and contain complex number, design freedom of designable left eigenvector are given.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.81-88
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• 1999

A conventional quarter-car suspension system is a single input system with one actuator. Thus, the performance enhancement for ride quality could be limited. In this paper, we propose a novel automotive suspension system for a quarter-car with two independent actuators to improve the control performance. The left eigenstructure assignment method for multi-variable systems has been applied to the proposed novel quarter-car model.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.5
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• pp.357-362
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• 2002

The underlying principle of fault detection via unknown input observer is to make the state estimation error independent of disturbances(or unknown inputs). In this paper, we present a systematic method that can exactly assign the eigenstructure with disturbance suppression and fault isolation capability. A desired eigenstructure for both fault isolation and disturbance suppression is obtained by an optimization method. For the dual purposes, terms for fault isolation and far disturbance suppression are included in the employed objective function for the optimization. The proposed scheme is applied to a simple example to confirm the usefulness of the method.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.345-345
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• 2000

This paper introduces a new design approach for robust sliding-mode control of a class of mismatched uncertainties. For this, we propose a design method of sliding-mode surface using eigenstructure assignment to be insensitive to perturbation in sliding-mode systems, and also find a formula which is shown bounds of mismatched uncertainties for stability of the system. Simulation results are given to illustrate the approach proposed in this paper.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.412-419
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• 1993

The transient responses of a linear system having undesired disturbances are dominantly governed by the system's left eigenstructure(eigenvalues/left eigenvectors). In control system design problem of altering the transient response of the system, both the controllability and the disturbance suppressibility, should be considered simultaneously to obtain a robust, effective controller. The controllability of the system may be degraded if the left eigenstructure is chosen to suppress the disturbance, or vice versa. In this paper, first, proposed are a modal disturbance suppressibility measure and an improved version of the modal controllability measure suggested by Hamdan and Nayfeh. Second, a simple and general left eigenstructure assignment scheme, considering both the proposed modal disturbance suppressibility measure and the improved version of modal controllability measure, is suggested. When the previous works are applied to assign the left eigenvectors may differ from the desired ones. But the proposed left eigenstructure assignment scheme makes it possible to achieve the desired colsed-loop eigenvalues exactly, provided the desired left eigenvectors reside in the achievable subspace. In case the desired left eigenvectors do not reside in the achievable subspace, the closed-loop eigenvalues are achieved exactly and the left eigenvectors are assigned to the best possible set of eigenvectors in the least square sense. Finally, a numerical example is included to confirm and demonstrate the usefulness of our propositions and to illustrate the proposed design scheme.

• International Journal of Control, Automation, and Systems
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• v.4 no.5
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• pp.653-659
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• 2006

The design of $H_2$-optimal control with regional pole assignment via state feedback in linear time-invariant systems is investigated. The aim is to find a state feedback controller such that the closed-loop system has the desired eigenvalues lying in some desired stable regions and attenuates the disturbance between the output vector and the disturbance vector. Based on a proposed result of parametric eigenstructure assignment via state feedback in linear systems, the considered $H_2$-optimal control problem is changed into a minimization problem with certain constraints, and a simple and effective algorithm is proposed for this considered problem. A numerical example and its simulation results show the simplicity and effectiveness of this proposed algorithm.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.39-44
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• 2003

It was shown that the robustness of deterministic observers with respect to modeling errors, measurement bias and round-off errors can be represented by a single performance index the condition number of the observer eigenvector matrix. In this paper, a robust observer for multi-output systems is designed using the left eigenstructure assignment, where the observer gain can not be determined uniquely with respect to the desired observer poles. Utilizing the eigenstructuer assignment for the robustness of the observer, the desired eigenvector matrix is selected to achieve the observer eigenvector matrix with the small condition number. The performance of the designed robust observer is evaluated in a spindle-drive simulation example where the load speed to be estimated based on the measured signals.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.206-213
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• 2001

An overlapping decentralized robust EA(eigenstructure assignment) controller is designed for an active suspension system of a vehicle based on a full car model with 7-degree of freedom. Using overlapping decomposition, the full car model is decentralized by two half car models. For each half car model, an effective and disturbance suppressible controller can be obtained by assigning appropriately a left eigenstructure of the system. The performance of the proposed overlapping decentralized robust EA controller is compared with that of a conventional centralized EA controller through computer simulations.