• International Journal of Control, Automation, and Systems
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• v.5 no.2
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• pp.111-116
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• 2007

The design problem of partial pole assignment (PPA) in two classes of frequency-domain MIMO models by constant gain feedback is investigated in this paper. Its aim is to design a constant gain feedback which changes only a subset of the open-loop eigenvalues, while the rest of them are kept unchanged in the closed-loop system. A near general parametric expression for the feedback gain matrix in term of a set of design parameter vectors and the set of the closed-loop poles, and a simple parametric approach for solving the proposed problem are presented. The set of poles do not need to be previously prescribed, and can be set undetermined and treated together with the set of parametric vectors as degrees of design freedom provided by the approach. An illustrative example shows that the proposed parametric method is simple and effective.

• International Journal of Control, Automation, and Systems
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• v.5 no.5
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• pp.501-507
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• 2007

This paper presents a new algorithm for the closed-loop $H_{\infty}$ control of a class of singularly perturbed nonlinear systems with an exogenous disturbance, using the successive Galerkin approximation (SGA). The singularly perturbed nonlinear system is decomposed into two subsystems of a slow-time scale and a fast-time scale in the spirit of the general theory of singular perturbation. Two $H_{\infty}$ control laws are obtained to each subsystem by using the SGA method. The composite control law that consists of two $H_{\infty}$ control laws of each subsystem is designed. One of the purposes of this paper is to design the closed-loop $H_{\infty}$ composite control law for the singularly perturbed nonlinear systems via the SGA method. The other is to reduce the computational complexity when the SGA method is applied to the high order systems.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.3
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• pp.333-344
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• 2014

This is the survey paper on the role of kinematics in robot development. The robot is considered as a form of mechanical systems which includes closed-chain loop system, open-chain loop system and closed and open switching system. To analyze these systems, kinematic notations has been developed in kinematics of mechanical theory since 1955 and has been applied in robotics. Several kinematic notations including Denavit-Hartenberg notations have been reviewed. The status of development of the spherical motor which has a great impact on the future robot advancement has reviewed, and research activity on a spherical motor and its application to 3-D spatial mechanisms at UNIST is introduced. For the open and closed switching mechanical systems, the bipedal robots' walking theories using Zero Moment Point are reviewed. And current status regarding bipedal robots based on newly developed passive dynamic walking theory is reviewed with the research activity at UNIST on this subject.

• International Journal of Control, Automation, and Systems
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• v.3 no.1
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• pp.109-116
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• 2005

The design of reconfiguring a class of second-order dynamic systems via proportional plus derivative (P-D) feedback is considered. The aim is to resynthesize a P-D feedback controller such that the eigenvalues of the reconfigured closed-loop system can completely recover those of the original close-loop system, and make the corresponding eigenvectors of the former as close to those of the latter as possible. Based on a parametric result of P-D feedback eigenstructure assignment in second-order dynamic systems, parametric expressions for all the P-D feedback gains and all the closed-loop eigenvector matrices are established and a parametric algorithm for this reconfiguration design is proposed. The parametric algorithm offers all the degrees of design freedom, which can be further utilized to satisfy some additional performances in control system designs. This algorithm involves manipulations only on the original second-order system matrices, thus it is simple and convenient to use. An illustrative example and the simulation results show the simplicity and effect of the proposed parametric method.

• International Journal of Control, Automation, and Systems
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• v.5 no.4
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• pp.379-387
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• 2007

In this paper, a nonlinear anti-sway controller for container cranes with load hoisting is investigated. The considered container crane involves a planar motion in conjunction with a hoisting motion. The control inputs are two (trolley and hoisting forces), whereas the variables to be controlled are three (trolley position, hoisting rope length, and sway angle). A novel feedback linearization control law provides a simultaneous trolley-position regulation, sway suppression, and load hoisting control. The performance of the closed loop system is shown to be satisfactory in the presence of disturbances at the payload and rope length variations. The advantage of the proposed control law lies in the full incorporation of the nonlinear dynamics by partial feedback linearization. The uniform asymptotic stability of the closed-loop system is assured irrespective of variations of the rope length. Simulation and experimental results are compared and discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.1
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• pp.69-78
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• 1999

In this study a new pattern of pressure control of hydraulic cylinder using high speed On-Off solenoid valve in the electro-hydraulic system has been suggested. The control valve is 3-way high speed On-Off solenoid valve which is operated by PWM(Pulse Width Modulation)control signal. The high speed On-Off solenoid valve has a tendency to induce severe pressure fluctuation in the hydraulic actuator so it has not been used for the purpose of closed loop control with direct pres-sure feedback. In this study closed loop control with direct pressure feedback is enabled by using a digital filter which has linear minimum mean square filter algorithm. Through some experiments it is confirmed that stable pressure control can be realized by the proposed control technique.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.144-149
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• 1993

This paper discusses a design of a nonlinear control for a class of single-input double-output nonlinear mechanical systems. When conventional linearization methods are applied to the mechanical systems, some problems of oscillation and unstable phenomena arise. The proposed nonlinear control system resolves these problems. In this design the eigenvalues of the closed-loop nonlinear system are assigned to desired locations and local asymptotic stability of the closed-loop system. is guaranteed. The design method is applied to an inverted pendulum system with a moving weight mechanism. Experimental results show that the proposed nonlinear controller is more effective for stability than the usual linear controller.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1754-1760
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• 2011

In this paper, a systematic design of a robust nonlinear multivariable variable structure controller based on state dependent nonlinear form is presented for the control of MIMO uncertain affine nonlinear systems with mismatched uncertainties and matched disturbance. After a MIMO uncertain affine nonlinear system is represented in the form of state dependent nonlinear system, a systematic design of a robust nonlinear variable structure controller is presented. To be linear in the closed loop resultant dynamics, the linear sliding surface is applied. A corresponding diagonalized control input is proposed to satisfy the closed loop global exponential stability and the existence condition of the sliding mode on the linear sliding surface, which will be investigated in Theorem 1. Through a design example and simulation study, the usefulness of the proposed controller is verified.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.101-104
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• 1997

In this paper, we deal with a quadratic stabilization by $H^{\infty}$ output feedback controllers with adjustable parameters. The designed controller contains a contractive time-varying gain which can be used to adjust the responses of the resulting closed-loop system. The free parameter expressed as time-varying gain is chosen so that a Lyapunov function of the closed-loop system descends as fast as possible. A numerical example is given to show the validity of proposed method..

• Earthquakes and Structures
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• v.23 no.4
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• pp.329-338
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• 2022

This work addresses the optimization controller design problem combining the AI evolution bat (EB) optimization algorithm with a fuzzy controller in the practical application of a reinforced concrete frame structure. This article explores the use of an intelligent EB strategy to reduce the dynamic response of Lead Rubber Bearing (LRB) composite reinforced concrete frame structures. Recently developed control units for plant structures, such as hybrid systems and semi-active systems, have inherently non-linear properties. Therefore, it is necessary to develop non-linear control methods. Based on the relaxation method, the nonlinear structural system can be stabilized by properly adjusting the parameters. Therefore, the behavior of a closed-loop system can be accurately predicted by determining the behavior of a closed-loop system. The performance and durability of the proposed control method are demonstrated by numerical simulations. The simulation results show that the proposed method is a viable and feasible control strategy for seismically tuned composite reinforced concrete frame structures.