• Title/Summary/Keyword: Loop technique

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Experimental Considerations in Tracking Control of HDD Dual Stage Actuator (HDD의 2단구동기를 이용한 트랙 추종 제어의 실험적 고찰)

  • Park, Sung-Joon;Park, No-Cheol;Yang, Hyun-Seok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.237-242
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    • 2000
  • The areal recording density of HDD(Hard Disk Drive) has been increasing by about 60% a year. In order to achieve high areal density, less track pitch is expected and more servo bandwidth is required. Dual stage actuator and servo controller for HDD have been suggested for achieving high track density as a possible solution. Dual-loop servo system is generally classified into a two-input-two-output system, but if we use an estimator for a two-input-two-output system, it can be converted into two input one output system. Since we can't control the dual stage servo system by the classical method, it requires a special technique; for example, Parallel Loop System, Master-Slave Loop System, Decoupled Master-Slave Loop System, and Dual Feedback Loop System. In this paper, we performed experimental evaluations of several types of control algorithm. Further experiments will be made in the future.

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Adaptive Cooperative Relay Transmission Technique Using Closed-loop MIMO Scheme for Duplex Communication System (양방향 통신 시스템에서 폐회로 다중 안테나 기법을 적용한 적응형 협동 중계 전송 기술)

  • Lee, Kwan-Seob;Kim, Young-Ju
    • Journal of Broadcast Engineering
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    • v.15 no.2
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    • pp.157-162
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    • 2010
  • In this paper, We propose that the adaptive cooperative relay transmission technique using closed-loop MIMO scheme for duplex communication system. As the mobility between relay and base station is little, closed-loop MIMO is better diversity gain than open-loop MIMO. At this time, more than one relaying terminals are included in one cooperative group to share their transmission and take precoding weight feedback. For minimization of throughput reduction caused by increasing feedback bits, we use codebook-based MRT that limit the number of feedback bits. Among the cooperative relay group, the best relays are selected from the base stataion and get the feedback. A protocol senarios are also proposed for this relay system.

A Design of Digital DLL Circuits For High-Speed Memory (고속 메모리동작을 위한 디지털 DLL회로 설계)

  • Lee, Joong-Ho;Cho, Sang-Bock
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.37 no.7
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    • pp.43-49
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    • 2000
  • We proposed ADD(Alternate Directional Delay) circuit technique as the DLL(Delay Locked Loop) circuits which technique is established the data valid window(tDV) in DDR(Double Data Rate) Synchronous DRAM. This technique could be decrease area-overhead which it could generated bidirectional clock simultaneously using only one delay chain block. In this paper for high speed memory with relatively small size. This technique decreased area-overhead more 2 times than SMD(Synchronous Mirror Delay) technique. ADD technique has 50ps-140ps jitter and the operation frequency has 166MHz-66MHz range.(at 2.5V, TYP. condition)

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Digital Implementation of Delta Modulation Technique for Current-Fed Active Power Filters (전류형 능동필터를 위한 델타변조제어기법의 디지탈 구현)

  • Kang, Byong-Hee;Hwang, Jong-Gyu;Gho, Jae-Soek;Mok, Hyung-Soo;Cho, Gyu-Ha
    • Proceedings of the KIEE Conference
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    • 1994.07a
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    • pp.400-402
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    • 1994
  • This paper presents a digital implementation of delta modulation Technique for Active Power Filters. Delta modulated scheme is to control the harmonic-compensating current indirectly by adjusting the capacitor voltage to be sinusoidal. The overall control system has two feedback loops. One is the outer propotional feedback for loop regulating the dc current of active filters and the other is the inner feedback loop for maintaining the ac current waveform to be sinusoidal, and have zero power factor angle(i.e. unity power factor). The characteristics of the proposed is investigated by digital simulation using ACSL and experimental results are obtained by TMS370C756 Single-Chip Microprocessor relative to analog delta modulation technique.

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A Study on the Fault-Tolerant and Bumpless Switching Control for Boiler Systems in the Power Plant (발전용 보일러 시스템의 이상허용 및 과도상태의 유연한 제어에 관한 연구)

  • Kwon, Oh-Kyu;Lee, Young-Sam
    • Proceedings of the KIEE Conference
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    • 1998.11c
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    • pp.1037-1040
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    • 1998
  • In this research a fault-tolerant and bumpless switching control is proposed for boiler systems used in the power plants. Firstly, three operating points are selected to control the nonlinear boiler through the full operational range, and the $H_{\infty}$ loop shaping controller and the model-based predictive controller(MBPC) are designed. To prevent the windup and bump problems which are caused by the actuator saturation and the controller switching, an anti-windup and bumpless transfer technique is adopted to the $H_{\infty}$ loop shaping controller. Also the constrained gain-scheduling technique is applied to MBPC to achieve the same objective. Secondly, the fault-tolerant control technique is proposed to continue the control action without stopping the boiler operation even in case of some faults. Through various simulation studies, the performances of the proposed control techniques are demonstrated.

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A Study on the Fault-Tolerant and Bumpless Switching Control for Boiler Systems in the Power Plant (발전용 보일러 시스템의 이상허용 및 과도상태의 유연한 제어에 관한 연구)

  • Kwon, Oh-Kyu;Lee, Young-Sam
    • Proceedings of the KIEE Conference
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    • 1998.11b
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    • pp.689-692
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    • 1998
  • In this research a fault-tolerant and bumpless switching control is proposed for boiler systems used in the power plants. Firstly, three operating points are selected to control the nonlinear boiler through the full operational range, and the $H_{\infty}$ loop shaping controller and the model-based predictive controller(MBPC) are designed. To prevent the windup and bump problems which are caused by the actuator saturation and the controller switching, an anti-windup and bump less transfer technique is adopted to the $H_{\infty}$ loop shaping controller. Also the constrained gain-scheduling technique is applied to MBPC to achieve the same objective. Secondly, the fault-tolerant control technique is proposed to continue the control action without stopping the boiler operation even in case of some faults. Through various simulation studies, the performances of the proposed control techniques are demonstrated.

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Research on In-band Spurious Evasion Techniques of Hybrid Frequency Synthesizer

  • Kim, Seung-Woo;Yoo, Woo-Sung
    • Journal of IKEEE
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    • v.19 no.2
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    • pp.176-185
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    • 2015
  • The study aims to a design hybrid frequency synthesizer in spectrum analyzer and to propose new techniques designed for evasion of in-band spurious. The study focuses on calculating the exact location of multiple phase locked loop of hybrid frequency synthesizer and spurious of direct digital synthesizer to evade in-band spurious outside of frequency range that the user wants to see and thereby simulating technique to improve input related spurious of spectrum analyzer for algorithm. The proposed technique is designed to calculate spurious evasion algorithm in central processing system when in-band spurious arises, and to move output frequency of DDS(direct digital synthesizer) into the place where no in-band spurious exists thereby improving performance of frequency synthesizer. The study used simulation and result representation to prove the effectiveness of the proposed technique.

A Study en the Fault-Tolerant and Bumpless Switching Control for Boiler Systems in the Power Plant (발전용 보일러 시스템의 이상허용 및 과도상태의 유연한 제어에 관한 연구)

  • Kwon, Oh-Kyu;Lee, Young-Sam
    • Proceedings of the KIEE Conference
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    • 1998.11a
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    • pp.369-372
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    • 1998
  • In this research a fault-tolerant and bumpless switching control is proposed for boiler systems used in the power plants. Firstly, three operating points are selected to control the nonlinear boiler through the full operational range, and the $H_{\infty}$ loop shaping controller and the model-based predictive controller(MBPC) are designed. To prevent the windup and bump problems which are caused by the actuator saturation and the controller switching, an anti-windup and bumpless transfer technique is adopted to the $H_{\infty}$ loop shaping controller. Also the constrained gain-scheduling technique is applied to MBPC to achieve the same objective. Secondly, the fault-tolerant control technique is proposed to continue the control action without stopping the boiler operation even in case of some faults. Through various simulation studies, the performances of the proposed control techniques are demonstrated.

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Microvascular Anastomosis Using 'Continuous Suture with Interrupted Knot' Technique (연속 봉합 단속 결찰법을 이용한 미세 혈관 문합법)

  • Choi, Moon-Su;Park, Sang-Hoon
    • Archives of Reconstructive Microsurgery
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    • v.8 no.1
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    • pp.22-27
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    • 1999
  • While the conventional end-to-end anastomotic technique is accepted as 'the golden standard' for microvascular anastomosis, it is time-consuming and tedious. In an effort to offer faster and safer ways of performing microvascular anastomoses, numerous anastomotic techniques have been proposed, but further refinements in microvascular techniques are still necessary. A 'continuous suture with interrupted knot' technique was devised for faster and safer anastomosis. It has been successfully used in microanastomoses of both artery and vein for free tissue transfer. It is a combination of the interrupted suturing technique and the continuous suturing technique. First, a continuous suture is made with the size of loop decreasing in order, and then the sutures are tied individually from the first loop to the last one as in the conventional interrupted suturing technique. It was applied clinically to fourteen patients over the past ten months and found to be a highly efficient technique that satisfied our needs. This 'continuous suture with interrupted knot' technique has several advantages over other techniques : The operative time is reduced comparing conventional interrupted suture technique. By delaying the tie and with the vessel walls kept separated, the risk of through-stitch can be reduced. Tying all the sutures at one time not only speed up the procedures, but also reduced the surgeon's fatigue. In addition, it has no problem of anastomotic stenosis which is a disadvantage of continuous suture technique. This technique proved to be faster and safer, and has patency equal to that of the conventional end-to-end anastomosis. It is of great help to the surgeon in reducing operative time, especially in clinical situations when many anastomoses are required, or lengthy grafting procedures are undertaken.

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Direct Digital Control of Single-Phase AC/DC PWM Converter System

  • Kim, Young-Chol;Jin, Lihua;Lee, Jin-Mok;Choi, Jae-Ho
    • Journal of Power Electronics
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    • v.10 no.5
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    • pp.518-527
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    • 2010
  • This paper presents a new technique for directly designing a linear digital controller for a single-phase pulse width modulation (PWM) converter systems, based on closed-loop identification. The design procedure consists of three steps. First, obtain a digital current controller for the inner loop system by using the error space approach, so that the power factor of the supply is close to one. The outer loop is composed of a voltage controller, a current control loop including a current controller, a PWM converter, and a capacitor. Then, all the components, except the voltage controller, are identified by a discrete-time equivalent linear model, using the closed-loop output error (CLOE) method. Based on this equivalent model, a proper digital voltage controller is then directly designed. It is shown through PSim simulations and experimental results that the proposed method is useful for the practical design of PWM converter controllers.