• Journal of Institute of Control, Robotics and Systems
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• v.7 no.3
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• pp.193-197
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• 2001

This paper presents a design method of sliding model control (SMC) for single input linear systems with mismatched uncertainties. We define a virtual state based on the controllable canonical form of the nominal system. And we defined a sliding surface for the augmented system with a virtual state. This sliding surface makes it possible to use the SMC technique with various types of controllers. In this paper, we construct a controller that combines SMC with robust controller. We design a robust controller for the system with mismatched uncertainties using a form of linear matrix inequality(LMI). We make a virtual state from this robust control input and the states of the nominal system. And we design a sliding model controller that stabilizes the overall closed-loop system.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.11
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• pp.868-873
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• 2003

$H_{\infty}$ control has been applied to the design of practical control systems widely because of its robustness. It can minimize $H_{\infty}$ norm of the transfer function between the desired output and the disturbances. The SMC(Sliding Mode Control) is more robust and give the better performance than the $H_{\infty}$ control if the matching condition is satisfied. A controller which can have the advantages of $H_{\infty}$ control and the SMC is proposed to add the robustness of the SMC to the $H_{\infty}$ controller. Its design is based on the augmented system of which dynamics have one higher order than that of the original system and has the same dynamic as the desired system in spite of uncertainties. The dynamic of proposed sliding surface is the same dynamic as the system controlled by $H_{\infty}$ controller without the uncertainties which satisfy the matching condition.

• Journal of Power Electronics
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• v.10 no.1
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• pp.1-8
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• 2010

A new scheme for sliding-mode control (SMC) of DC-DC converters with a constant switching frequency is proposed. The scheme is based on the averaging model and the output signal of the controller is $d^+$ or $d^-$ instead of the on or off signal of a direct sliding-mode (SM) controller or the continuous signal d = $u_{eq}$ of an indirect SM controller. Two approaches using the new scheme are also proposed and the design procedures for a buck converter are given in detail. The first approach called constant $d^+$ and $d^-$ SMC is simple, cost effective and dynamically fast. In order to improve the dynamic characteristics of the reaching phase and to alleviate chattering, the second approach called reaching law SMC is also presented. Analyses and simulation results demonstrate the feasibility of the proposed scheme.

• Smart Structures and Systems
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• v.19 no.5
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• pp.577-585
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• 2017

In this paper, an adaptive fuzzy sliding mode controller (AFSMC) is designed to reduce dynamic responses of seismically excited structures. In the conventional sliding mode control (SMC), direct implementation of switching-type control law leads to chattering phenomenon which may excite unmodeled high frequency dynamics and may cause vibration in control force. Attenuation of chattering and its harmful effects are done by using fuzzy controller to approximate discontinuous part of the sliding mode control law. In order to prevent time-consuming obtaining of membership functions and reduce complexity of the fuzzy rule bases, adaptive law based on Lyapunov function is designed. To demonstrate the performance of AFSMC method and to compare with that of SMC and fuzzy control, a linear three-story scaled building is investigated for numerical simulation based on the proposed method. The results indicate satisfactory performance of the proposed method superior to those of SMC and fuzzy control.

• Journal of Power Electronics
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• v.14 no.5
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• pp.980-988
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• 2014

This paper proposes an online gain tuning algorithm for a robust sliding mode speed controller of surface-mounted permanent magnet synchronous motor (SPMSM) drives. The proposed controller is constructed by a fuzzy neural network control (FNNC) term and a sliding mode control (SMC) term. Based on a fuzzy neural network, the first term is designed to approximate the nonlinear factors while the second term is used to stabilize the system dynamics by employing an online tuning rule. Therefore, unlike conventional speed controllers, the proposed control scheme does not require any knowledge of the system parameters. As a result, it is very robust to system parameter variations. The stability evaluation of the proposed control system is fully described based on the Lyapunov theory and related lemmas. For comparison purposes, a conventional sliding mode control (SMC) scheme is also tested under the same conditions as the proposed control method. It can be seen from the experimental results that the proposed SMC scheme exhibits better control performance (i.e., faster and more robust dynamic behavior, and a smaller steady-state error) than the conventional SMC method.

• Structural Engineering and Mechanics
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• v.26 no.5
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• pp.517-544
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• 2007

This study shows a fuzzy tuning scheme to fuzzy sliding mode controller (FSMC) for seismic isolation of earthquake-excited structures. The sliding surface can rotate in the phase plane in such a direction that the seismic isolation can be improved. Since ideal sliding mode control requires very fast switch on the input, which can not be provided by real actuators, some modifications to the conventional sliding-mode controller have been proposed based on fuzzy logic. A superior control performance has been obtained with FSMC to deal with problems of uncertainty, imprecision and time delay. Furthermore, using the fuzzy moving sliding surface, the excellent system response is obtained if comparing with the conventional sliding mode controller (SMC), as well as reducing chattering effect. For simulation validation of the proposed seismic response control, 16-floor tall building has been considered. Simulations for six different seismic events, Elcentro (1940), Hyogoken (1995), Northridge (1994), Takochi-oki (1968), the east-west acceleration component of D$\ddot{u}$zce and Bolu records of 1999 D$\ddot{u}$zce-Bolu earthquake in Turkey, have been performed for assessing the effectiveness of the proposed control approach. Then, the simulations have been presented with figures and tables. As a result, the performance of the proposed controller has been quite remarkable, compared with that of conventional SMC.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1646-1647
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• 2007

In the conventional sliding mode control(SMC), the states of controlled systems are linearly dependent because of the characteristic of the sliding surface. This means that conventional SMC can not add its robustness to other control methods. To overcome this problem, a special sliding surface with additional dynamic states has been proposed. However the additional dynamic states make it difficult to design a controller because the order ofa controller becomes higher. So, in this paper, a novel sliding surface design method, which does not require any additional dynamic state, is proposed. The relationships between the states with desirable responses can be expressed by using SVM and included in a sliding mode dynamics. The robust optimal controller with the optimal performanceand the robustness of SMC is considered.

• Journal of Power Electronics
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• v.15 no.3
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• pp.753-762
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• 2015

This paper presents a nonlinear sliding mode control (SMC) scheme with a variable damping ratio for interior permanent magnet synchronous motors (IPMSMs). First, a nonlinear sliding surface whose parameters change continuously with time is designed. Actually, the proposed SMC has the ability to reduce the settling time without an overshoot by giving a low damping ratio at the initial time and a high damping ratio as the output reaches the desired setpoint. At the same time, it enables a fast convergence in finite time and eliminates the singularity problem with the upper bound of an uncertain term, which cannot be measured in practice, by using a simple adaptation law. To improve the efficiency of a system in the constant torque region, the control system incorporates the maximum torque per ampere (MTPA) algorithm. The stability of the nonlinear sliding surface is guaranteed by Lyapunov stability theory. Moreover, a simple sliding mode observer is used to estimate the load torque and system uncertainties. The effectiveness of the proposed nonlinear SMC scheme is verified using comparative experimental results of the linear SMC scheme when the speed reference and load torque change under system uncertainties. From these experimental results, the proposed nonlinear SMC method reveals a faster transient response, smaller steady-state speed error, and less sensitivity to system uncertainties than the linear SMC method.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.215-218
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• 1995

In this paper, a sliding mode controller (SMC) which can be characterized by high accuracy, fast response and robustness is applied to speed control of AC-SERVO motor. The control input is changed to continuous one in the boundary layer to reduce the chattering phenomenon, and the boundary layer converges to zero when the state variables of system reach to steady state values. The integral compensator is added to reduce steady state error and to provide the continuous torque reference. The acceleration which is necessary to get the sliding plane is estimated by an observer. Sliding surface is included in control input to enhance the robustness and transient response without increasing sliding mode controller gain. The proposed controller is implemented by DSP(digital signal processor). The effectiveness of the proposed control scheme for speed controller is shown by the real-time experimental results in the paper.

• Journal of Power Electronics
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• v.11 no.5
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• pp.639-654
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• 2011

This paper presents a Current Distribution Control design for Paralleled Positive Output Elementary Super Lift Luo Converters (PPOESLLCs) operated in Continuous Conduction Mode using a Sliding Mode Controller (SMC). Manipulating the higher current requirement of the load through the paralleling of POESLLCs, results in a current inequality. This is mainly due to dissimilarities in the power semiconductor switches and circuit components used in POESLLCs, which may lead to converter failures. In order to balance the proper load current sharing and the load voltage regulation of PPOESLLCs, a SMC is developed. The SMC is designed for the inherently variable-structured of POESLLCs by using the state-space average based model. The static and dynamic performance of the developed controller with PPOESLLCs is validated for its robustness to perform over a wide range of operating conditions through both a laboratory prototype and MatLab/Simulink models, which are compared with a Proportional-Integral (PI) controller. Theoretical analysis, simulation and experimental results are presented to demonstrate the feasibility of the developed SMC along with the complete design procedure.