• Title/Summary/Keyword: Open Loop

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Open-Loop Precoding for Spatial Multiplexing Systems in Correlated Channels (상관 채널에서의 공간다중화 기법을 위한 개루프 프리코딩 기법)

  • Jang, Jungyup;Kim, Dong Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.1
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    • pp.58-60
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    • 2015
  • In this letter, an open-loop precoding is proposed to enhance the performance of SM in transmit correlated MIMO channels. The proposed method is derived by observing the effect of feedback error on the minimum distance precoder, and can mitigate the performance degradation without any feedback information.

Enhancing the Accuracy for the Open-loop Resolver to Digital Converters

  • Karabeyli, Fikret Anil;Alkar, Ali Ziya
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.192-200
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    • 2018
  • In this study, improvements for error correction, speed, position, and rotation calculation algorithms have been proposed to be used in resolver to digital conversion (RDC) systems. The proposed open-loop system drives the resolver and uses the output signals of the resolver signal to estimate the real time position, the instant speed, and the rotation count with high resolution and accuracy even at high speeds and noise. The proposed solution implements strong features of both closed and open loop based systems while eliminating their weak points. The improvements proposed is resistant to noise owing to digital FIR filter and data averaging techniques. The implementation used for proof of concept is implemented on a hardware using an FPGA and configurable to be used by any resolver.

A Study on the Optical Pickup Design using the Bode Diagram (주파수 선도를 이용한 광픽업 설계 연구)

  • 손도현;홍삼열;최인호;김영중;김진용
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.967-971
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    • 2001
  • The frequency characteristics of the optical pickup are investigated indirectly from the bode diagram of the open loop system and the actuator. However, there is necessity of acquiring the optical pickup bode diagram in a view of the differences in the frequency characteristics. One of the differences is that bode diagrams of the optical pickup are differ to that of the actuator and the other is that bode diagrams of the open loop system include controller, gains and filters. So this paper presents the method acquiring the optical pickup bode diagram. In addition, usefulness of the optical pickup bode diagram was demonstrated by being applied to the optical pickup design. The reason of reducing the development period and acquiring the frequency characteristics of the optical system, the optical pickup bode diagram has many merits in the optical pickup design before acquiring the stable bode diagram of the open loop system.

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Design of a Robust Tracking Controller by the Estimation of Vibration Quantity (진동량 추정을 통한 강인 트랙킹 제어기의 설계)

  • Lee, Moon-Noh;Jin, Kyoung-Bog;Yun, Ki-Bong
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.9
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    • pp.856-860
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    • 2007
  • This paper presents a robust tracking controller design method for the track-following system of an optical recording device. A tracking loop gain adjustment algorithm is introduced to accurately estimate the tracking vibration quantity in spite of the uncertainties of the tracking actuator. A minimum tracking open-loop gain is calculated by the estimated tracking vibration quantity and a tolerable limit of tracking error. A robust tracking controller is designed by considering a robust $H_\infty$ control problem with the weighting function of a slightly larger gain than the minimum tracking open-loop gain. The proposed controller design method is applied to the track-following system of an optical recording device and is evaluated through the experimental result.

A Study on State-Space Model Identification of AC Servo Motor System (AC 서보 전동기 시스템의 상태공간 모델 식별에 관한 연구)

  • 이태훈;김상환;송봉철;원충연;이상석
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2000.11a
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    • pp.199-204
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    • 2000
  • Generally, The systems are so complex that it not possible to obtain reasonable model using physical insight. Also a model based on physical insight contains a number of unknown parameters even if the structure is derived from physical laws. To solve these problems, the systems identification is described in this paper. So, AC servo motor system which has both open loop and closed loop is selected as an example for identification. A state-space model of AC servo motor system is identified through open loop experiment and identified through closed loop experiment and using pole placement integral controller to open loop system. As the results, From ARMA model, We have obtained continuous-time state space model.

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Open Loop Technique in FORMOSAT-3/COSMIC mission

  • Yeh, Wen-Hao;Chiu, Tsen-Chieh;Liou, Yuei-An;Huang, Cheng-Yung
    • Proceedings of the KSRS Conference
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    • 2007.10a
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    • pp.394-396
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    • 2007
  • Radio occultation (RO) technique has been used in planetary science since 1960s. When signal goes through atmosphere, it is refracted due to the gradient of atmospheric refractivity. In 1995, the first low earth orbit (LEO) satellite, MicroLab-1, was launched to conduct RO mission. It receives the signal from global positioning system (GPS) satellites. After MicroLab-1, other RO missions, such as CHAMP, SAC-C, and GRACE, are executed in several years later. In 2006, Taiwan launched six LEO satellites for RO mission. The mission name is Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC). Under some abnormal situations, multipath and strong fluctuation in phase and amplitude of the signal appear in moist troposphere. Therefore, open loop (OL) technique has been applied to replace traditional phase lock loop (PLL) technique. In this paper, we will summarize the retrieval processing procedure and discuss the advantages and disadvantages of OL technique.

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Parallel String Matching and Optimization Using OpenCL on FPGA (FPGA 상에서 OpenCL을 이용한 병렬 문자열 매칭 구현과 최적화 방향)

  • Yoon, Jin Myung;Choi, Kang-Il;Kim, Hyun Jin
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.1
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    • pp.100-106
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    • 2017
  • In this paper, we propose a parallel optimization method of Aho-Corasick (AC) algorithm and Parallel Failureless Aho-Corasick (PFAC) algorithm using Open Computing Language (OpenCL) on Field Programmable Gate Array (FPGA). The low throughput of string matching engine causes the performance degradation of network process. Recently, many researchers have studied the string matching engine using parallel computing. FPGA's vendors offer a parallel computing platform using OpenCL. In this paper, we apply the AC and PFAC algorithm on DE1-SoC board with Cyclone V FPGA, where the optimization that considers FPGA architecture is performed. Experiments are performed considering global id, local id, local memory, and loop unrolling optimizations using PFAC algorithm. The performance improvement using loop unrolling is 129 times greater than AC algorithm that not adopt loop unrolling. The performance improvements using loop unrolling are 1.1, 0.2, and 1.5 times greater than those using global id, local id, and local memory optimizations mentioned above.

Feedback Loop Design for Micro Gyroscope

  • Sung, Woon-Tahk;Song, Jin-Woo;Lee, Jang-Gyu;Taesam Kang
    • 제어로봇시스템학회:학술대회논문집
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    • 2002.10a
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    • pp.39.4-39
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    • 2002
  • This paper presents a design and implementation of a PID feedback control loop for micro gyroscope. The feedback control loop improves the gyroscope performance such as linearity, bandwidth, and bias stability for micro gyroscope which is basically a high-Q system and exhibits a low performance with an open loop control. The designed and implemented feed-back control loop is applied to the SNU-Bosch MEMS gyroscope to demonstrate the improvement with the feedback control loop. The bandwidth is improved to 60Hz from 25Hz of open loop control. The linearity becomes 0.5% from 1%. The bias stability is improved to 0.03 deg/sec from 0.06 deg/sec.

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