• Journal of the Korean Society for Precision Engineering
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• v.17 no.9
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• pp.81-86
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• 2000

This paper was carried out to investigate the characteristics of interlaminar fracture toughness of foam core sandwich structures under opening loading mode by using the double cantilever beam (DCB) specimens in Carbon/Epoxy and foam core composites. instead of using symmetric geometry of DCB specimen non-symmetric DCB specimen was used to calculate the interlaminar fracture toughness. Three approaches for calculating the energy release rate({{{{ {G }_{IC } }}}}) were compared. Fracture toughness of foam core sandwich structures by autoclave vacuum bagging and hotpress were compared and analyzed. Experiment nonlinear beam bending FEM method were performed. Suggested bonding surface compensation and equivalent area inertia moment was used to calculate the energy release rate in nonlinear analytical results. The conclusions among experimental nonlinear analytical and FEM results was observed. The vacuum bagging method was shown to be able to substitute method in stead of autoclave without serious loss of Mode I energy release rate({{{{ {G }_{IC }}}}}) to be able to substitute method in stead of autoclave without serious loss of Mode I energy release rate({{{{ {G }_{IC }}}}}).

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2011-2020
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• 1992

This paper discusses about real time control applying sliding mode to robot manipulators whose nonlinear terms, which are inertia term, Corilis term and centrifugal force mterm, are regarded as disturbances. We could simplify the dynamic equations of a manipulator and servo system, which are composed of linear elements and nonlinear elements, by assuming that non-linear terms are external disturbance. By simplifying that equation, we could easily obtain a control input which satisfy sliding mode. We proposed a new control input algorithm to decrease chattering in the application of sliding mode control of manipulator whose nonlinear elements are regarded as disturbances. We could take impulse response of linear elements of dynamic equations of a robot manipulator and servo system by Signal Compression Method. So then, we could obtain the unknown parametes of its linear lements, which are used to obtain switching parameter satisfying sliding mode, by Signal Compression Method. In this experiments, we used DSP(Digital Signal Processor) controller to suppress chattering by obtaining a switching speed and to carry out real time control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1020-1026
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• 2014

A problem of sliding mode control is chattering because of controle input signal included unknown disturbance and nonlinear input parameters. This paper presents a sliding mode controller design to inverted pendulum system. In this paper, a sliding mode control algorithm to reduce a chattering is proposed. The reduction of chattering is accomplished by smoothing function for nonlinear control input. In this method, the dynamic equations of the inverted pendulum is decoupled by considering nonlinear parameters and external disturbances. Therefore, this study is applied to obtain switching control inputs for sliding mode controller. The proposed technique is tested to the control of inverted pendulum through computer simulations. The result shown reduced chattering in control input.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.4
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• pp.320-328
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• 2003

This paper proposes a new nonlinear adaptive guidance law. Fourth order state equation for integrated guidance and control loop is formulated considering target uncertainties and control loop dynamics. The state equation is further changed into the normal form by nonlinear coordinate transformation. An adaptive nonlinear guidance law is proposed to compensate for the uncertainties In both target acceleration and control loop dynamics. The proposed law adopts the sliding mode control approach with adaptation fer unknown bound of uncertainties. The present approach can effectively solve the existing guidance problem of target maneuver and the limited performance of control loop. We provide the stability analyses and demonstrate the effectiveness of our scheme through simulations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.3
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• pp.623-629
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• 2010

In this paper, a new robust variable structure controller based on a nonlinear integral type sliding surface is presented for the control of uncertain systems with mismatched uncertainties and disturbance. A nonlinear integral type sliding surface is suggested for removing the reaching phase. After its ideal sliding dynamics is obtained, the two design methods are presented. A corresponding control input is proposed to satisfy the closed loop stability in the sense of Lyapunov and the existence condition of the sliding mode on the nonlinear integral type 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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• 1996.10b
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• pp.1496-1499
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• 1996

A nonlinear tracking control technique developed for the control of nonlinear systems has been applied to the autopilot design of missile system. The difficulties in the application of inversion based control methods such as input-output feedback linearization and sliding mode control due to nonminimum phase characteristics are discussed. To avoid the stability problem associated with unstable zero dynamics, the input-output feedback linearization is applied with output-redefinition method to normal acceleration control. The output-redefinition method gives an indirect way to apply the nonlinear controls to nonminimum phase plants by redefining the plant output such that the tracking control of the modified output ensures the asymptotic tracking of the original output. The numerical simulation shows satisfactory results both for nominal and for slightly perturbed missile systems adopting the sliding mode control technique. However, the robustness problem in this method is briefly investigated and verified with the simulation.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2236-2238
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• 2004

This paper proposes the self-recurrent wavelet neural network (SRWNN) observer based sliding mode control (SMC) method for nonlinear systems. Unlike the classical SMC, we assume that all states of nonlinear systems are not measured and design the SRWNN observer to measure the states of nonlinear systems. The SRWNN in the observer is used for approximating the observer system's gain. To generate the control input for controlling the nonlinear system, the measured states are used. The sliding surface with a boundary layer is defined to remove the chattering of the control input. Simulation result to show the effectiveness of the SRWNN observer is presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1612-1619
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• 2017

In this note, a complete proof of Utkin's theorem is presented for SI(single input) uncertain nonlinear systems. The invariance theorem with respect to the two nonlinear transformation methods so called the two diagonalization methods is proved clearly, comparatively, and completely for SI uncertain nonlinear systems. With respect to the sliding surface and control input transformations, the equation of the sliding mode i.e., the sliding surface is invariant, which is proved completely. Through an illustrative example and simulation study, the usefulness of the main results is verified. By means of the two nonlinear transformation methods, the same results can be obtained.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.526-529
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• 1998

In this paper, we proposed a nonlinear sliding mode controller to regulate the swinging angle of Overhead Crane System. Roughly speaking, the controller is designed to regulate an output(the swing angle) while providing internal stability. It is difficult to apply many of standard nonlinear control design techniques. In contrast to control that use a command generator and possibly a time-varying feedback, our control law is simple autonomous nonlinear controller. We analyze the stability of the closed-loop system using an $L_2$ Sliding surface conditions approach on a nonlinear feedback linearization of the system about the desired periodic orbit. One can easily extend this approach to analyze the robustness of the control system with respect to disturbances and parameter variations.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.2
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• pp.162-168
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• 1997

Digital variable structure controller(DVSC) is implemented to control the temperature for the hot water heating circulating pump control system. For the DVSC, a control algorithm is suggested, which using a nonlinear sliding surface and a PID sliding surface outside and inside of steady state error boundary layer, respectively. Smith predictor algorithm is used for the compensation of long dead time. The DVSC of the suggested algorithm yields improved control performance compared with the one of existing algorithm. The system responses with the suggested DVSC shows good responses without overshoot and steady state error inspite of heating load change. By decreasing sampling time, dead time and rise time are increasing, and system output noise by flow dynamics is amplified.