• 한국정밀공학회지
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• 제19권7호
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• pp.163-170
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• 2002

This paper presents some measures far the optimization of the thermal behavior of linear motors, which are used as a high speed feed mechanism in machine tools. Thermo-Sandwich-Construction using two cooling circuits and an insulation layer shows an effective cooling system for linear motors. Conducting sheet can be also used to reduce heat flow from linear motor to machine table. Cooling pipe is a simple and effective cooling system for the secondary part of synchronous linear motor. Through the combination of the Thermo-Sandwich-Construction, conducting sheet and cooling pipe the thermally optimized linear motor shows a well improved thermal behavior in comparison with the prototype motor.

• 전자공학회논문지B
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• 제33B권5호
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• pp.1-9
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• 1996

In this paper, a parameter identification method for a discrete-time linear system using multi-layer neural network is proposed. The parameters are identified with the combination of weights and the output of neuraons of a neural network, which can be used for a linear and a nonlinear controller. An adaptive output tracking architecture is designed for the linear controller. And, the nonlinear controller. A sliding mode control law is applied to the stabilizing the nonlinear controller such that output errors can be reduced. The effectiveness of the proposed control scheme is illustrated through simulations.

• 대한산업공학회지
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• 제25권3호
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• pp.290-297
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• 1999

In interior point methods for linear programming, we must solve a linear system with a symmetric positive definite matrix at every iteration, and Cholesky factorization is generally used to solve it. Therefore, if Cholesky factorization is not done successfully, many iterations are needed to find the optimal solution or we can not find it. We studied methods for improving the numerical stability of Cholesky factorization and the accuracy of the solution of the linear system.

• 대한수학회논문집
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• 제26권1호
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• pp.37-49
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• 2011

We investigate the asymptotic equivalence for linear differential systems by means of the notions of $t_{\infty}$-similarity and strong stability.

• Journal of applied mathematics & informatics
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• 제20권1_2호
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• pp.293-303
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• 2006

This paper describes a numerical scheme for optimal control of a time-dependent linear system to a moving final state. Discretization of the corresponding differential equations gives rise to a linear algebraic system. Defining some binary variables, we approximate the original problem by a mixed integer linear programming (MILP) problem. Numerical examples show that the resulting method is highly efficient.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.38-38
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• 2000

To fulfill recent requirements for high quality products in steel rolling process, fast responding and easily tunab control system is required and ILQ(Inverse Linear Quadratic) control system may be one of such alternatives. In this paper characteristics of ILQ control and its application to BUR(Back-Up-Roll) eccentricity in strip rolling mill is discussed and compared to polynomial control approaches. Also the rolling mill model and basic principle to control thickness of srip are introduced with control effect by polynomial methods.

• Smart Structures and Systems
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• 제9권4호
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• pp.373-392
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• 2012

Tracking control of systems with variable stiffness hysteresis using a gain-scheduled (GS) controller is developed in this paper. Variable stiffness hysteretic system is represented as quasi linear parameter dependent system with known bounds on parameters. Assuming that the parameters can be measured or estimated in real-time, a GS controller that ensures the performance and the stability of the closed-loop system over the entire range of parameter variation is designed. The proposed method is implemented on a spring-mass system which consists of a semi-active independently variable stiffness (SAIVS) device that exhibits hysteresis and precisely controllable stiffness change in real-time. The SAIVS system with variable stiffness hysteresis is represented as quasi linear parameter varying (LPV) system with two parameters: linear time-varying stiffness (parameter with slow variation rate) and stiffness of the friction-hysteresis (parameter with high variation rate). The proposed LPV-GS controller can accommodate both slow and fast varying parameter, which was not possible with the controllers proposed in the prior studies. Effectiveness of the proposed controller is demonstrated by comparing the results with a fixed robust $\mathcal{H}_{\infty}$ controller that assumes the parameter variation as an uncertainty. Superior performance of the LPV-GS over the robust $\mathcal{H}_{\infty}$ controller is demonstrated for varying stiffness hysteresis of SAIVS device and for different ranges of tracking displacements. The LPV-GS controller is capable of adapting to any parameter changes whereas the $\mathcal{H}_{\infty}$ controller is effective only when the system parameters are in the vicinity of the nominal plant parameters for which the controller is designed. The robust $\mathcal{H}_{\infty}$ controller becomes unstable under large parameter variations but the LPV-GS will ensure stability and guarantee the desired closed-loop performance.

• 제어로봇시스템학회논문지
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• 제21권4호
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• pp.342-348
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• 2015

This paper presents a two-wheel balancing mobile robot with linear workspace extension structures. The two-wheel mobile robot has two linear motions at the waist and shoulder to have extended workspace. The linear motion of the waist and shoulder provides some structural advantages. A dynamic equation of the simplified robot system is derived. Simulation studies of the position control of the robot system are performed based on the dynamic equations. The dynamic relationship between a two-wheel mobile system and linear extension mechanism is observed by simulation studies.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.561-565
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• 2005

Sliding mode control (SMC) is an effective method of controlling systems with uncertainties which satisfy the so-called matching condition. However, how to effectively handle mismatched uncertainties of systems is still an ongoing research issue in SMC. Several methods have been proposed to design a stable sliding surface even if mismatched uncertainties exist in a system. Especially, it is presented that robustness and efficiency of SMC for linear systems with mismatched uncertainties can be improved by reducing mismatched uncertainties in the reduced-order system. The reduction method needs a new sliding surface with an additional component based on Lyapunov redesign technique. In this paper, a stable sliding surface which contains additional component to reduce the influence of mismatched uncertainties, is introduced. It is designed by using linear matrix inequalities that guarantees the stability of the system. A numerical example demonstrates the validity of the proposed scheme.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.934-938
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• 1988

In this paper we present a method of determining the unknown degree of any 2D discrete linear shift-invariant system which is characterized only by the coefficients of the double power series of a transfer function, i.e. a 2D impulse response array. Our method is based on a 2D extension of Berlekamp-Massey algorithm for synthesis of linear feedback shift registers, and it gives a novel approach to identification and approximation of 2D linear systems, which can be distinguished in its simplicity and potential of applicability from the other 2D Levinson-type algorithms. Furthermore, we can solve problems of 2D Pade approximation and 2D system reduction on a reasonable assumption in the context of 2D linear systems theory.