• Title/Summary/Keyword: Combined mode

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Improvement of One-Cycle Controller Response with a Current Mode Controller

  • Ruzbehani, Mohsen;Zhou, Luowei;Mirzaei, Nasser
    • Journal of Power Electronics
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    • v.10 no.1
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    • pp.21-26
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    • 2010
  • The most important feature of the one-cycle control method is its excellent ability in line disturbance rejection. However, when it is used as a controller in dc-dc converters, it has an undesirable transient response. The voltage overshoot at the transient time, which usually exists in one-cycle controlled converters, is unwanted in many applications and it is sometimes hazardous. In this paper, it is shown that the combination of a one-cycle controller with a current mode controller, can improve the transient response and consequently the overshoot can be controlled. Therefore, the combined controller has the excellent line disturbance rejection of a one-cycle controller and the output current limiting capability of current mode controllers. Because in this scheme a one-cycle controller is the master controller, the problem of instability of current mode control, will not happen. By simulation and a practical prototype, the capability of the method is shown.

Controller Design for an Autonomous Underwater Vehicle Using Estimated Hydrodynamic Coefficients

  • Kim, Joon-Young
    • Journal of Ocean Engineering and Technology
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    • v.20 no.6 s.73
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    • pp.7-17
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    • 2006
  • Depth and heading control of an AUV are considered to follow the predetermined depth and heading angle. The proposed control algorithm is designed. based on a sliding mode control using estimated hydrodynamic coefficients. The hydrodynamic coefficients are estimated with conventional nonlinear observer techniques, such as sliding mode observer and extended Kalman filter. By using the estimated coefficients, a sliding mode controller is constructed for the combined diving and steering maneuver. The simulation results of the proposed control system are compared with those of control system with true coefficients. This paper demonstrates the proposed control system, discusses the mechanisms that make the system stable and follows the desired depth and heading angle, accurately, in the presence of parameter uncertainty.

A REFINED SEMI-ANALYTIC DESIGN SENSITIVITIES BASED ON MODE DECOMPOSITION AND NEUMANN SERIES IN REDUCED SYSTEM (축소모델에서 강체모드 분리와 급수전개를 통한 준해석적 민감도 계산 방법)

  • Kim, Hyun-Gi;Cho, Maeng-Hyo
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.491-496
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    • 2003
  • In sensitivity analysis, semi-analytical method(SAM) reveals severe inaccuracy problem when relatively large rigid body motions are identified for individual elements. Recently such errors of SAM resulted by the finite difference scheme have been improved by the separation of rigid body mode. But the eigenvalue should be obtained first before the sensitivity analysis is performed and it takes much time in the case that large system is considered. In the present study, by constructing a reduced one from the original system, iterative method combined with mode decomposition technique is proposed to compute reliable semi-analytical design sensitivities. The sensitivity analysis is performed by the eigenvector acquired from the reduced system. The error of SAM caused by difference scheme is alleviated by Von Neumann series approximation.

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Design of a sliding Mode Controller Using a Neural Compensator (신경회로망 보상기를 이용하는 슬라이딩 모드 제어기 설계)

  • Lee, Min-Ho;Jung, Soon-Ki
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.3
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    • pp.256-262
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    • 2000
  • This paper proposes a new sliding mode controller combined with a multi-layer neural network using the error back propagation learning algorithm,, The network acts as a compensator of the conventional sliding mode controller to improve the control performance when initial assumptions of uncertainty bounds of system parameters are violated. The proposed controller can reduce th steady state error of conventional sliding mode controller with the boundary layer technique Computer simulation results show that the proposed method is effective to control dynamic systems with unexpectably large uncertainties.

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Sliding Mode Control with Friction Observer for a Precise Mechanical System in the Presence of Nonlinear Dynamic Friction

  • Han, Seong-Ik
    • Transactions on Control, Automation and Systems Engineering
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    • v.4 no.4
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    • pp.296-304
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    • 2002
  • A position tracking control schemes on the precise mechanical system in presence of nonlinear dynamic friction is proposed. A nonlinear dynamic friction is regarded as the bristle friction model to compensate effects of friction. The conventional sliding mode controller often has been used as a non-model-based friction controller, but it has a poor tracking performance in high-precision position tracking application since it completely cannot compensate the friction effect below a certain precision level. Thus to improve the precise position tracking performance, we propose the sliding mode control method combined with the friction-model-based observer having tunable structure of the transient response. Then this control scheme has a good transient response as well as the high precise tracking performance compared with the conventional sliding mode control without observer and the control system with similar type of observer. The experiments on the bali-screw drive table with the nonlinear dynamic friction show the feasibility of the proposed control scheme.

Adaptive sliding mode control with self-tuning the boundary layer thickness (자기동조 경계층 범위를 갖는 적응 슬라이딩모드 제어)

  • Park, Jae-Sam
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.1
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    • pp.8-14
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    • 2000
  • In this paper, three adaptive sliding mode control algorithms, which self-tune both the sliding mode gain and the boundary layer thickness, are proposed. The first algorithm uses a gain adaptation rule is combined with the boundary layer thickness adaptatioin rule to satisfy the sliding condition. In the third algorithm, the computation burden of the second algorithm is reduced further, and therefore no extra cost is required for real-time implementation. Due to the mixed sliding mode gain and the boundary layer thickness adaptation scheme, the tracking error and the chattering of the control input can be reduced greatly.

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Controller design for an autonomous underwater vehicle using nonlinear observers

  • Negahdaripour, Shahriar;Cho, So-Hyung;Kim, Joon-Young
    • International Journal of Ocean System Engineering
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    • v.1 no.1
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    • pp.16-27
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    • 2011
  • The depth and heading control of an autonomous underwater vehicle (AUV) are considered to follow the predetermined depth and heading angle. The proposed control algorithm was based on a sliding mode control, using estimated hydrodynamic coefficients. The hydrodynamic coefficients were estimated employing conventional nonlinear observer techniques, such as sliding mode observer and extended Kalman filter. Using the estimated coefficients, a sliding mode controller was constructed for a combined diving and steering maneuver. The simulated results of the proposed control system were compared with those of a control system that employed true coefficients. This paper demonstrated the proposed control system, and discusses the mechanisms that make the system stable and accurately follow the desired depth and heading angle in the presence of parameter uncertainty.

Modified adaptive complementary sliding mode control for the longitudinal motion stabilization of the fully-submerged hydrofoil craft

  • Liu, Sheng;Niu, Hongmin;Zhang, Lanyong;Xu, Changkui
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.11 no.1
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    • pp.584-596
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    • 2019
  • This paper presents a Modified Adaptive Complementary Sliding Mode Control (MACSMC) system for the longitudinal motion control of the Fully-Submerged Hydrofoil Craft (FSHC) in the presence of time varying disturbance and uncertain perturbations. The nonlinear disturbance observer is designed with less conservatism that only boundedness of the derivative of the disturbance is required. Then, a complementary sliding mode control system combined with adaptive law is designed to reduce the bound of stabilization error with fast convergence. In particularly, the modified complementary sliding mode surface which contains the estimation of the disturbance can reduce the switching gain and retain the normal performance of the system. Moreover, a hyperbolic tangent function contained in the control law is utilized to attenuate the chattering of the actuator. The global asymptotic stability of the closed-loop system is demonstrated utilizing the Lyapunov stability theory. Ultimately, the simulation results show the effectiveness of the proposed approach.

A Study on the Cost Function Based on Operating Modes for Combined Cycle Power Plant (복합화력발전기의 운전조합별 비용함수에 관한 연구)

  • Lee, Jaehee;Yoon, Hyeok-Jun;Oh, Chang-Jin;Noh, Yu-Rim;Joo, Sung-Kwan;Ryu, Sangmin;Wi, Young-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.3
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    • pp.358-364
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    • 2018
  • In this study, the theoretical methodology is presented for estimating cost function based on operating modes for Combined Cycle Power Plant. The proposed method has estimated cost functions using the relationship between the gas turbine heat input and the output ratio of the steam turbine. In order to verify the proposed method, a regression analysis was performed using the single cost function estimated by the existing performance test method and the cost function for each operating mode estimated by the proposed method. The results of case studies using the 2016 generator input and output data are presented to show the effectiveness of the proposed method.

Evaluation of the Probability of the Steel Beam to Collapse in Accordance with the Normal Distribution Load (철골보의 정규하중분포에 따른 파손확률 평가)

  • Song, Chang-Young
    • Journal of Korean Society of Disaster and Security
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    • v.7 no.1
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    • pp.43-50
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    • 2014
  • Based on the reliability theory, the risk assessment of steel beams is performed by the determination of failure probability. In the calculation, bending, shearing and combined (bending + shearing) modes are examined. The resistance and the loads on the beam are assumed to be normal distribution. To investigate the failure probability changes, total load applied at the mid span of beam is divided into 1 to 1 and 1 to 2 ratio and then these divided loads are placed on the trisected points on beam. The change of boundary conditions at beam ends are also included in the investigation. It shows that failure is governed by the combined mode for the present beams and the second order bound analysis of failure probability is not crucial. On the whole failure probability decreases with increasing end restraints at the beam ends with some exception.