• Title/Summary/Keyword: closed loop control

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A Note to the Stability of Fuzzy Closed-Loop Control Systems

  • Hong, Dug-Hun
    • Journal of the Korean Data and Information Science Society
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    • v.12 no.1
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    • pp.89-97
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    • 2001
  • Chen and Chen(FSS, 1993, 159-168) presented a reasonable analytical model of fuzzy closed-loop systems and proposed a method to analyze the stability of fuzzy control by the relational matrix of fuzzy system. Chen, Lu and Chen(IEEE Trans. Syst. Man Cybern., 1995, 881-888) formulated the sufficient and necessary conditions on stability of fuzzy closed-loop control systems. Gang and Chen(FSS, 1996, 27-34) deduced a linguistic relation model of a fuzzy closed loop control system from the linguistic models of the fuzzy controller and the controlled process and discussed the linguistic stability of fuzzy closed loop system by a linguistic relation matrix. In this paper, we study more on their models. Indeed, we prove the existence and uniqueness of equilibrium state $X_e$ in which fuzzy system is stable and give closed form of $X_e$. The same examples in Chen and Chen and Gang and Chen are treated to analyze the stability of fuzzy control systems.

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An Analytical Framework for Imperfect DS-CDMA Closed-Loop Power Control over Flat Fading

  • Choe, Sang-Ho
    • ETRI Journal
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    • v.27 no.6
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    • pp.810-813
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    • 2005
  • This letter presents an analytical framework for a performance analysis of the imperfect direct-sequence code division multiple access (DS-CDMA) closed-loop power control (CLPC) loop with loop delay, channel estimation error, and power control command bit error as the parameters under a Rayleigh flat fading environment. The proposed model is verified through a comparison between analytical results and simulation ones.

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An Auto Pole Shift Adaptive Control (자동 극점이동 적응제어)

  • Kim, Eung-Seok;Yang, Hai-Won
    • Proceedings of the KIEE Conference
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    • 1989.07a
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    • pp.146-150
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    • 1989
  • In the pole assignment strategy, the closed loop poles are placed at prespecified locations. The amount of control effort required is to some extent proportional to the distance of the proposed closed loop locations of the poles from their open loop locations. The poor choice of closed loop locations may result in Large control effort and it may nuke the system unstable. To overcome this problem, pole shift control strategy is described in this paper. The validity of the proposed control strategy is assured through some simulations.

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Design of a Luenberger Observer-based Current Sensorless Multi-loop Control for Boost Converters

  • Li, Xutao;Chen, Minjie;Shinohara, Hirofumi;Yoshihara, Tsutomu
    • IEIE Transactions on Smart Processing and Computing
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    • v.5 no.1
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    • pp.22-28
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    • 2016
  • Multi-loop control of a boost converter needs a current-sensing circuit to detect the inductor current. Current sensorless multi-loop control reduces the cost, size and weight of the converter. The Luenberger observer (LO) is widely used to estimate the inductor current for current sensorless control of a switching converter. However, the design of the LO-based sensorless multi-loop control has not been well presented, so far. In this paper, a closed-loop characteristics evaluation method is proposed to design an LO-based current sensorless multi-loop control for boost converters. Simulations show evaluations of the closed-loop characteristics. Practical experiments on a digital processor confirm the simulations.

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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A Stator Flux Oriented V/f Control of Induction Motor in Low Speed Range

  • Kim Young-Real
    • Proceedings of the KIPE Conference
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    • 2001.10a
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    • pp.466-469
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    • 2001
  • In this paper, closed loop V/f control of induction motor has been implemented by the estimated speed. Closed loop V/f control improve the performance of induction motor drive system at low speed compared to open loop V/f control. However, closed loop V/f control need speed sensor. By using the estimated speed, closed loop V/f control is possible without speed sensor. Rotor speed is calculated from the difference between synchronous frequency and slip angular frequency. 3-phase voltage reference is obtained from synchronous frequency. And the PWM technique using space vector PWM is applied in this scheme. In the space vector PWM, effective time of 3-phase voltage reference is used to simplify the calculation of effective voltage time. This scheme is simple to implement and one chip microprocessor was used in experimental system.

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Implementation of Profibus-FMS Network for Real-Time Closed-Loop Control System (실시간 폐루프 제어 시스템을 위한 Profibus-FMS 네트워크의 구현)

  • Lee, Kyung-Chang;Kim, Kee-Woong;Kim, Hee-Hyun;Lee, Suk
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.10
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    • pp.911-917
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    • 2000
  • As many sensors and actuators are used in various automated systems, the application of network to real-time distributed control system is gaining acceptance in many industries. In order to take advantages of networking, however, the network should be carefully designed to satisfy real-time distributed control. This paper presents an implementation method of closed-loop control using Profibus-FMS. In order to implement a closed-loop control system, we used industrial computers with Profibus-FMS network cards and a DC servo motor. Through various experiments, the step response of the control system with network was compared with the reference response without network.

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Design of Closed Loop Pipe Cooling System (냉각수 순환 형태의 파이프 쿨링 공법의 설계)

  • 박찬규;왕인수;구자중
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2001.11a
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    • pp.52-57
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    • 2001
  • In order to control hydration heat in mass concrete, pipe cooling method has been widely used. The pipe cooling method leads to the decrease of curing period by lagging materials as well as the decrease of temperature difference between center and surface of mass concrete member, There are two methods in the pipe cooling system, which are open loop system and closed loop system. However open loop pipe cooling system cannot be applied to the mass concrete structures when cooling water supply is difficult. To control hydration heat of high strength mass foundation in the central area of city, closed loop pipe cooling system was developed to solve the cooling water supply. This paper reports the performance results of hydration heat control with closed loop pipe cooling system.

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Position Control of a 3 dof Closed-loop Cylinder System Using ER Valve Actuators (ER 밸브 작동기를 이용한 3자유도 폐회로 실린더 시스템의 위치제어)

  • 최승복;조명수
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.3
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    • pp.165-173
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    • 2000
  • This Paper presents the position tracking control of a closed-loop cylinder system using electro-rheological(ER) valve actuators. After manufacturing three sets of cylindrical ER valves on the basis of Bingham model of ER fluid, a 3 dof(degree-of-freedom) closed-loop cylinder system having the heave, roll and pitch motions is constructed. The governing equations of motion are derived using Lagrange's equation and a control model is formulated by considering nonlinear characteristics of the system. Sliding mode controllers are then designed fer these ER valve actuators in order to achieve position tracking control. The effectiveness of trajectory tracking control performance of the proposed cylinder system is demonstrated through computer simulation and experimental implementation of the sliding mode controller.

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