• Title/Summary/Keyword: Feedback loop

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Design of a repetitive controller for the system with unstructured uncertainty (비구조적인 불확실성을 가지는 시스템에 대한 반복 제어기의 설계)

  • 도태용;문정호;정명진
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.779-782
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    • 1996
  • Repetitive control is a proposed control strategy in view of the internal model principle and achieves a high accuracy asymptotic tracking property by implementing a model that generates the periodic signals of period into the closed-loop system. Since the repetitive control system contains a periodic signal generator with positive feedback loop, which reduces the stability margin, in the overall closed-loop system, the stability of the closed-loop system should be considered as an important problem. In case that a real system has plant uncertainties which are not represented through modeling, the robust stability problem of the repetitive control system has not been considered sufficiently. In this paper, we propose the robust stability condition for the system with modeling uncertainty. The proposed robust stability condition will be obtained using the robust performance condition in the H$_{\infty}$ control. Moreover, by use of the proposed robust stability condition, we propose a procedure that designs a repetitive controller and a feedback controller simultaneously which can stabilize the overall closed-loop system robustly and which can also do the closedloop system without repetitive controller..

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Robust Pole Assignment in a Specified Disk

  • Nguyen, Van-Giap;Nguyen, Tan-Tien;Lee, Gun-You;Kim, Sang-Bong
    • Transactions on Control, Automation and Systems Engineering
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    • v.2 no.2
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    • pp.116-120
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    • 2000
  • This paper presents a method to assign robustly the closed loop system's poles in a specified disk by a state feedback for a linear time invariant system with structured or unstructured uncertainties. THe proposed robust design procedure includes two steps. Firstly, the perturbed closed loop matrix $A_{cl p}$ = $A_{cl}$ + Δ$A_{cl}$ is rearranged such that it is a function of the nominal closed loop matrix $A_{cl}$. Hence, we can control the positions of the perturbed closed loop poles by choosing $A_{cl}$ appropriately. Secondly, the feedback control law F that assigns the closed loop poles of the perturbed system in a specified disk is determined from the equation $A_{cl}$ = A + BF. A procedure for finding F is proposed based on partitioning every matrix of the equation $A_{cl}$ = A + BF in the horizontal direction.

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Two Degree of Freedom Robust Controller Design of a Seeker Scan-Loop (탐색기 주사루프의 2자유도 강인제어기 설계)

  • Lee, Ho-Pyeong;Song, Chang-Seop
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.10
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    • pp.157-165
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    • 1995
  • The new formulation of designing the two degree of freedom(TDF) robust controller is proposed using $H_{\infty}$optimization and model matching method. In this formulation the feedback controller and feedforward controller are designed in a single step using $H_{\infty}$optimization procedure. Roughly speaking, the feedback controller is designed to meet robust stability and disturbance rejection specifications, while the feedforward controller is used to improve the robust model matching properties of the closed loop system. The proposed formulation will be illustrated and evaluated on a seeker scan-loop. And the performances of TDF robust controller are compared with those of the $H_{\infty}$ controller designed using Loop Shaping Design Procedure proposed by McFarlane and Glover.lover.

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State Feedback $H^{\infty}$ Controller Design for Linear Systems with Time-delays (시간지연을 가지는 선형 시스템에 대한 상태궤환 $H^{\infty}$제어기 설계)

  • Jeong, Eun-Tae;Lee, Gap-Rae;Lee, Jae-Myeong;Park, Hong-Bae
    • Journal of Institute of Control, Robotics and Systems
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    • v.2 no.1
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    • pp.1-4
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    • 1996
  • This paper presents a state feedback $H^{\infty}$ controller design method for linear systems with delayed states and inputs. We derive a sufficient condition that the closed-loop system is asymptotically stable for all time-delays and that the $H^{\infty}$-norm of the closed-loop transfer function is less than or equal to some prescribed level $\gamma$. And we propose a sufficient condition for the existence of a state feedback $H^{\infty}$ controller using a form of linear matrix inequality(LMI). Furthermore, we show that the state feedback $H^{\infty}$ controllers can be obtained from solutions satisfying LMI.

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Stabilization and $H_\infty$ control of linear systems with static output feedback (상수 출력궤환 선형 시스템의 안정화 및 $H_\infty$ 제어기 설계)

  • Kim, Hyeong-Jin;Kim, Myeong-Soon;Kim, Jin-Hoon
    • Proceedings of the KIEE Conference
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    • 2003.11b
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    • pp.111-114
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    • 2003
  • In this paper, we consider the stabilization and $H_\infty$ control of linear systems with static output feedback control. The static output feedback control represents the simplest closed-loop control that can be realized in practice, and, moreover, it is less expensive to be implemented and is more reliable. In spite of its advantages, it is one of the open problems which is not sloved analytically or numerically yet. After decompose the closed-loop system into feedback form, by adopting the small gain theorem, we obtain a sufficient condition for stabilization and a sufficient condition for It control expressed as linear matrix inequalites. Finally, we show the usefulness of our results by a numerical example.

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Feedback Analysis of Transcutaneous Energy Transmission with a Variable Load Parameter

  • Yang, Tianliang;Zhao, Chunyu;Chen, Dayue
    • ETRI Journal
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    • v.32 no.4
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    • pp.548-554
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    • 2010
  • The transcutaneous energy transmission system (TETS) composed of a Class-E amplifier may operate at a state away from the optimum power transmission due to the load variation. By introducing the feedback-loop technique, the TETS can keep the optimum state with constant output voltage by adjusting the important design parameters, that is, the duty ratio and frequency of the driving signal and the supply voltage. The relations between these adjusted parameters and the load are investigated. The effectiveness of the feedback technique is validated through a design example with a variable load parameter. The experimental results show that the Class-E amplifier in the feedback loop can keep operating at the optimum state under the condition of up to 50 percent variation of the load value.

Characteristics of Boost Active Power Factor Correction Converter (부스트 능동 역률개선 컨버터의 특성)

  • Jang, Jun-Young;Lin, Chi-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.12
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    • pp.1152-1159
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    • 2015
  • Switching power supply systems are widely used in many industrial fields. Power factor correction (PFC) circuits have a tendency to be applied in new power supply designs. The PFC circuit with a boost converter using an input power source is studied in this paper. In a boost PFC circuit, there are two feedback control loops: a current feedback loop and a voltage feedback loop. In this paper, the regulation performance gained by using the output voltage and compensator to improve the transient response presented at the continuous conduction mode (CCM) of the boost PFC circuit is analyzed. The validity of the designed boost PFC circuit is confirmed by both MATLAB simulation and experimental results.

Emulator Circuit for a Flux Locked Loop for Detection of Magnetocardiography Signal (심자도 신호 검출을 위한 Flux Locked Loop (FLL) Emulation 회로)

  • 안창범;이동훈;김인기;장경섭;김기태;정동현;최중필
    • Proceedings of the IEEK Conference
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    • 2003.07c
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    • pp.2749-2752
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    • 2003
  • Magnetocardiography is a very weak biomagnetic field generated from the heart. Since the magnitude of the biomagnetic field is in the order of a few pico Tesla, it is measured with a superconducting quantum interference device (SQUID). SQUID is a transducer converting magnetic flux to voltage, however, its range of linear conversion is very restricted. In order to overcome the narrow dynamic range. a flux locked loop is used to feedback the output field with opposite polarity to the input field so that the total Held becomes zero. This prevents the operating point of the SQUID from moving too far away from the null point thereby escape from the linear region. In this paper, an emulator for the SQUID sensor and feedback coil is proposed. Magnetic courting between the original field and the generated field by the feedback coil is emulated by electronic circuits. By using the emulator, FLL circuits are analyzed and optimized without SQUID sensors. The emulator may be used as a test signal for multi-channel gain calibration and system maintenance.

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Mixed $H_2/H_{\infty}$ Output Feedback Controller Design for PLL Loop Filter with Uncertainties and Time-delay (시간지연과 불확실성을 가지는 위상동기루프의 루프필터에 대한 혼합 $H_2/H_{\infty}$ 출력궤환 제어기 설계)

  • 이경호;한정엽;박홍배
    • Proceedings of the IEEK Conference
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    • 2003.07c
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    • pp.2589-2592
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    • 2003
  • In this paper, a robust mixed H$_2$/H$\_$$\infty$/ output feedback control method is applied to the design of loop filter for PLL carrier phase tracking. The proposed method successfully copes with large S-curve slope uncertainty and a significant decision delay in the closed-loop that may exist In modern receivers due to a convolutional decoder or an equalizer. The objective is to design an output feedback controller which minimizes the H$_2$performance while satisfying the H$\_$$\infty$/ performance to guarantee the gain margin and phase margin for linear time invariant(LTI) polytopic uncertain systems. LMIs based approach is given to solve this problem. We can verify the H$\_$$\infty$/ performance satisfaction and minimize the phase detector error through the simulation result.

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Direct multivariable quantitative feedback theory (직접식 다변수 정량적 피드백 이론)

  • Park, Myoung-Soo;Lee, Jae-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.3
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    • pp.562-568
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    • 1998
  • During the past three decades, several techniques have been suggested for robust performance design of multivariable systems within the framework of Quantitative Feedback Theory. They are all characterized and limited by the use of loop transmission inversion. A new approach within framework is described which leads to a design tehnique without loop transmission inversion. Complete sequential design algorithms are derived for performance specifications in terms of plant input disturbance, sensitivity, complimentary sensitivity and control effort.