• Title/Summary/Keyword: spin torque

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Development of 100Nm-class Control Moment Gyroscopes for Industrial Applications (100Nm급 산업용 제어모멘트자이로 개발)

  • Lee, Seon-Ho;Kim, Dae-Kwan;Kim, Yong-Bok;Yong, Ki-Lyuk;Choi, Dong-Soo;Park, Do-Hwan;Kim, Il-Jong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.2
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    • pp.172-178
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    • 2015
  • The control moment gyroscope(CMG) which is well known as an effective high-torque-generating device is applicable to space vehicles, airplanes, ships, automobiles, robotics, etc. for attitude stabilization and maneuver. This paper deals with the overall details of 100Nm-class CMG development for various industrial applications, and provides the activities and results associated with the CMG system-level requirement analysis, the motor subsystem design/manufacturing/integration, the construction of ground support equipment, and the performance test and evaluation. The performance test reveals that the CMG generates the torque output more than 120Nm in as-designed operation of spin motor and gimbal motor.

Patent Analysis of MRAM Technology (차세대 자기저항메모리 MRAM 기술의 특허동향 분석)

  • Noh, S.J.;Lee, J.S.;Cho, J.U.;Kim, D.K.;Kim, Y.K.;Yoo, Y.M.;Ha, M.Y.;Seo, J.W.
    • Journal of the Korean Magnetics Society
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    • v.19 no.1
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    • pp.35-42
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    • 2009
  • Among the next generation memory, MRAM (Magnetic Random Access Memory) is worthy of notice for substituting the preexisting memory thanks to its non-volatile property and other advantages. Recently perpendicular MRAM and spin transfer torque MRAM techniques are under active investigation to realize a high density and low power consumption. As a result, there are increasing of patents applications for high density, low current density for magnetization switching and high thermal stability. In this paper, we analyze the trend of patent applications and registrations about MRAM and propose a direction of future investigation.

Study on Direct Teaching Algorithm for Remote Center Motion of Surgical Assistant Robot using Force/Torque Sensor (힘/토크 센서를 이용한 수술보조로봇의 원격중심운동 직접교시 알고리즘 연구)

  • Kim, Minhyo;Jin, Sangrok
    • The Journal of Korea Robotics Society
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    • v.15 no.4
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    • pp.309-315
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    • 2020
  • This study shows a control strategy that acquires both precision and manipulation sensitivity of remote center motion with manual traction for a surgical assistant robot. Remote center motion is an essential function of a laparoscopic surgical robot. The robot has to keep the position of the insertion port in a three-dimensional space, and general laparoscopic surgery needs 4-DoF (degree-of-freedom) motions such as pan, tilt, spin, and forward/backward. The proposed robot consists of a 6-axis collaborative robot and a 2-DoF end-effector. A 6-axis collaborative robot performs the cone-shaped trajectory with pan and tilt motion of an end-effector maintaining the position of remote center. An end-effector deals with the remaining 2-DoF movement. The most intuitive way a surgeon manipulates a robot is through direct teaching. Since the accuracy of maintaining the remote center position is important, direct teaching is implemented based on position control in this study. A force/torque sensor which is attached to between robot and end-effector estimates the surgeon's intention and generates the command of motion. The predefined remote center position and the pan and tilt angles generated from direct teaching are input as a command for position control. The command generation algorithm determines the direct teaching sensitivity. Required torque for direct teaching and accuracy of remote center motion are analyzed by experiments of panning and tilting motion.

An Attitude Control and Stabilization of an Unstructured Object using CMG Subsystem (자이로 구동장치를 이용한 공중물체의 자세제어 및 안정화)

  • Lee, Geon-Yeong;Gwon, Man-O
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.49 no.8
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    • pp.459-466
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    • 2000
  • In this paper, we propose an attitude controller for an unstructured object using CMG(Control Moment of Gyro) subsystem, which has a stabilizer function. The CMG subsystem consists of one motor for spinning the wheel and the other motor for turning the outer gimbal. While the wheel of CMG subsystem is spinning at high speed, applying force to the spin axis of the wheel leads the torque about the vertical axis. We utilize the torque to control the attitude of object in this study. For the stabilizer function, in additiion, holding the load at the current position, the power applied to the gimbal motor of CMG will be cut, which result in the braking force to stop the load by gyro effect. However, due to the gear reduction connected to outer gimbal, slow load motion cannot generate the braking force. Thus, in this study, we are willing to make a holding force by applying control power to the gimbal motor from the signal of piezoelectric gyroscopic sensor that detected the angular velocity of the load. These two features are demonstrated in experiment, carrying a beam with crane. As a result, load was started to rotate by controlling gimbal positiion and was stopped by turning off the gimbal power. Moreover, slow movement of the load was also rejected by additional control with gyroscopic sensor.

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An Implementation of Balance Beam Controller(New Construction Machinery) for an Attitude Control and Stabilization of an Unstructured Object (공중물체의 자세제어 및 안정화를 위한 밸런스 빔 제어기(신건설장비) 구현)

  • Yi Keon Young;Kim Jin-Oh
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.52 no.1
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    • pp.38-44
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    • 2003
  • In this study, the balance beam control subsystem, new type of construction machinery using the mechanism of CMG (control moment gyro), for the attitude control of an unstructured object such as a beam carried by a tower crane, is designed and implemented. The balance beam controller consists of a wheel spinning at high speed and an outer gimbal for controlling the attitude of the wheel. Two motors, one for the wheel and the other for the gimbal, are used. Applying force to the spin axis of the wheel, as an input of the system, leads the torque about the axis because of the gyro effects. This torque is used to control the attitude of the unstructured object in this study. For the stabilizer function, in addition, holding the load at the current position, the attitude of the wheel is freed by cutting the power applied to the gimbal motor of the balance beam controller, which result in the braking force to stop the load by gyro effect. The works presented here include the mechanical system of the balance beam controller, the remote controller, the servo controller and the control software for the system. We also present experimental results to show that the system we proposed is useful as a new construction machinery which can control the attitude of the beam hanging from a tower crane.

Studies of Effects of Current on Exchange-Bias: A Brief Review

  • Bass, J.;Sharma, A.;Wei, Z.;Tsoi, M.
    • Journal of Magnetics
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    • v.13 no.1
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    • pp.1-6
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    • 2008
  • MacDonald and co-workers recently predicted that high current densities could affect the magnetic order of antiferromagnetic (AFM) multilayers, in ways similar to those that occur in ferromagnetic (F) multilayers, and that changes in AFM magnetic order can produce an antiferromagnetic Giant Magnetoresistance (AGMR). Four groups have now studied current-driven effects on exchange bias at F/AFM interfaces. In this paper, we first briefly review the main predictions by MacDonald and co-workers, and then the results of experiments on exchange bias that these predictions stimulated.

A Locality-Aware Write Filter Cache for Energy Reduction of STTRAM-Based L1 Data Cache

  • Kong, Joonho
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.1
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    • pp.80-90
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    • 2016
  • Thanks to superior leakage energy efficiency compared to SRAM cells, STTRAM cells are considered as a promising alternative for a memory element in on-chip caches. However, the main disadvantage of STTRAM cells is high write energy and latency. In this paper, we propose a low-cost write filter (WF) cache which resides between the load/store queue and STTRAM-based L1 data cache. To maximize efficiency of the WF cache, the line allocation and access policies are optimized for reducing energy consumption of STTRAM-based L1 data cache. By efficiently filtering the write operations in the STTRAM-based L1 data cache, our proposed WF cache reduces energy consumption of the STTRAM-based L1 data cache by up to 43.0% compared to the case without the WF cache. In addition, thanks to the fast hit latency of the WF cache, it slightly improves performance by 0.2%.

Novel Self-Reference Sense Amplifier for Spin-Transfer-Torque Magneto-Resistive Random Access Memory

  • Choi, Jun-Tae;Kil, Gyu-Hyun;Kim, Kyu-Beom;Song, Yun-Heub
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.1
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    • pp.31-38
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    • 2016
  • A novel self-reference sense amplifier with parallel reading during writing operation is proposed. Read access time is improved compared to conventional self-reference scheme with fast operation speed by reducing operation steps to 1 for read operation cycle using parallel reading scheme, while large sense margin competitive to conventional destructive scheme is obtained by using self-reference scheme. The simulation was performed using standard $0.18{\mu}m$ CMOS process. The proposed self-reference sense amplifier improved not only the operation speed of less than 20 ns which is comparable to non-destructive sense amplifier, but also sense margin over 150 mV which is larger than conventional sensing schemes. The proposed scheme is expected to be very helpful for engineers for developing MRAM technology.