• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.419-422
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• 1996

In this paper, we consider variable structure controller design of a active magnetic bearing(AMB). In particular, we design a switching hyperplane, considering coupling characteristic among each magnet. This method is designed by applying decentralized control method. Controller design consist of two factors that is, one is linear control part to drive state variables to zero asymptotically and the other is a nonlinear controller part to maintain within neighborhood of switching hyperplane. Finally, A control method designed here is checked by simulation, which shows good results.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.205-209
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• 1999

This paper proposes a variable structure position controller for an induction motor(IM) which uses a reaching law and an integral compensating nonlinear switching function. With the reaching law, reaching mode can be established quantitatively during transient state so that dynamic control performance is improved. With the integral compensating nonlinear switching function, both very low overshoot and high steady state control accuracy can be obtained by compensating the states chattering problem due to the unmodelled dynamics of inverter and feedback sensors. For experiment a digital servo driver which consists of a DSP and an IPM inverter was developed. With the various experimental results, IM position control performance was verified.

• 전기학회논문지
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• 제64권4호
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• pp.578-585
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• 2015

Electromagnetic levitation system(EMLS) is one of the well known nonlinear systems. Often, it is not easy to control an EMLS due to its high nonlinearity. In this paper, we first apply two linearization method(jacobian and input-output feedback linearization) to design two feedback controllers for an EMLS. Then, by observing the advantages of each controller, we design a switching control algorithm which engage two controllers depending on the position of the steel ball in order to achieve the improved performance over each controller. The validity of our switching control approach is verified via both simulation and actual experimental results.

• 제어로봇시스템학회논문지
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• 제16권12호
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• pp.1197-1200
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• 2010

The problem of designing a nonlinear sliding surface for an uncertain system is considered. The proposed sliding surface comprises a linear time invariant term and an additional time varying nonlinear term. It is assumed that a linear sliding surface parameter matrix guaranteeing the asymptotic stability of the sliding mode dynamics is given. The linear sliding surface parameter matrix is used for the linear term of the proposed sliding surface. The additional nonlinear term is designed so that a Lyapunov function decreases more rapidly. By including the additional nonlinear term to the linear sliding surface parameter matrix we obtain a nonlinear sliding surface such that the speed of responses is improved. We also give a switching feedback control law inducing a stable sliding motion in finite time. Finally, we give an LMI-based design algorithm, together with a design example.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.119-122
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• 2005

A algorithm for control and performance of a pulse-density-modulated (PDM) series-resonant voltage source inverter developed for corona-dischange precesses is presented. The PDM inverter produces either a square-wave ac-voltage state or a zero-voltage state at its ac terminals to control the average output voltage under constant dc voltage and operating frequency. Moreover it can achieve zero-current-switching (ZCS) and zero-voltage-switching (ZVS) in all the operating condition for a reduction of switching lost. Even though the corona discharge load with a strong nonlinear characteristics, new high frequency resonant inverter is shown the wide range power control from 5% to 100%.

• Transactions on Control, Automation and Systems Engineering
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• 제4권4호
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• pp.347-355
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• 2002

Obstacle avoidance of underactuated robot manipulators using switching computed torque method (SCTM) is presented. One fundamental feature of this novel method is to use partly stable controllers (PSCs) in order to fulfill the ultimate control objective. Here, we use genetic algorithms (GAs) to acquire the optimum switching sequence of the control actions for a given time frame with the available set of elemental controllers, depending on which links/variables are controlled. The effectiveness of the concept is illustrated by taking a three-degrees-of-freedom (DOF) manipulator and showing enhanced performance of the proposed control methodology.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1534-1544
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• 2002

The TDCSA(Time Delay Control with Switching Action) method, which consists of Time Delay Control(TDC) and a switching action of sliding mode control(SMC), has been proposed as a promising technique in the robust control area, where the plant has unknown dynamics with parameter variations and substantial disturbances are preset. When TDCSA is applied to the plant with saturation nonlinearity, however, the so-called windup phenomena are observed to arise, causing excessive overshoot and instability. The integral element of TDCSA and the saturation element of a plant cause the windup phenomena. There are two integral effects in TDCSA. One is the integral effect occurred by time delay estimation of TDC. Other is the integral term of an integral sliding surface. In order to solve this problem, we have proposed an anti-windup scheme method for TDCSA. The stability of the overall system has been proved for a class of nonlinear system. Experiment results show that the proposed method overcomes the windup problem of the TDCSA.

• International Journal of Control, Automation, and Systems
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• 제4권6호
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• pp.669-681
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• 2006

In this work, a new method of design adaptive controllers for SISO systems based on multiple models and switching is presented. The controller selects the model from a given set, according to a switching rule based on output prediction errors. The goal is to design, at each sample instant, a predictive control law that ensures the robust stability of the closed-loop system and achieves the best performance for the current operating point. At each sample the proposed control scheme identifies a set of linear models that best characterizes the dynamics of the current operating region. Then, it carries out an automatic reconfiguration of the controller to achieve the best possible performance whilst providing a guarantee of robust closed-loop stability. The results are illustrated by simulations a nonlinear continuous and stirred tank reactor.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1031-1035
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• 1993

In this paper, we suggest a new algorithm diminishing the chattering in sliding mode control by setting a dead-band along the switching line on the phase plane although nonlinear terms of an nonlinear system are regarded as disturbances and apply this algorithm to the trajectory control of SCARA robot By this algorithm, we can expect the high performance of the trajectory trajet of an industrial robot which needs a robust and simple algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.95.4-95
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• 2001

In this paper, we proposed and analyze an robust adaptive control scheme for uncertain nonlinear systems using Universal function approximators. The proposed scheme completely overcomes the singularity problem which occurs in the indirect adaptive feedback linearizing control. No projection in the estimated parameters and no switching in the control input are needed. The stability of the closed-loop systems is guaranteed in the Lyapunov standpoint.