• Title/Summary/Keyword: 롤 각

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A Study of Aerodynamic Modelling for Fin Unfolding Motion Analysis (공력면 전개 모사를 위한 공력 모델링 연구)

  • Jung, Suk-Young;Yoon, Sung-Joon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.5
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    • pp.420-427
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    • 2008
  • For simulation of a fin unfolding motion for the various aerodynamic conditions, equations and moments applying to the unfolding fin were modelled. Aerodynamic roll moment consists of the static roll moment and the damping moment, which were obtained through wind tunnel tests and numerical analyses respectively. Panel method was used to compute the roll damping coefficient with deflected fin, whose angle was equivalent to angle of attack due to the deployment motion. Roll damping coefficient is a function of angle of attack, sideslip angle, and deployment angle but not of angular velocity of deployment. Simulation with aerodynamic damping model gave more similar deployment time compared to fin deployment test results.

Roll Angle Estimation of a Rolling Airframe Using a GPS and a Roll Rate Gyro (단일 GPS와 롤각속도계를 이용한 롤 회전 비행체의 롤자세각 추정)

  • Hong, Ju-Hyeon;Kim, Dusik;Ryoo, Chang-Kyung;Lee, Chang-Hun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.2
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    • pp.133-140
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    • 2015
  • In this paper, a roll angle estimation method of a rolling airframe using a low grade GPS and a roll rate gyro is proposed. The strength of the received signal of the GPS antenna attached on the rolling airframe is maximized when the GPS satellite is placed on the plane determined by the x-axis of the rolling airframe and the GPS antenna axis. Under the assumption that the x-axis of the rolling airframe is coincident with its velocity vector, the roll angle of the rolling airframe is calculated from the relative position vector of the satellite to the GPS when the GPS signal strength becomes maximum. The Kalman filter combined with a roll rate gyro is introduced to increase the determination accuracy of the roll angle. The performance of the proposed method is verified via 6-DOF simulations.

Load Sharing Control of Driven Roll in Continuous Caster (연속주조기에서 스트랜드 구동롤의 인발력 분배 제어)

  • 천창근;김철우
    • The Transactions of the Korean Institute of Power Electronics
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    • v.8 no.4
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    • pp.321-327
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    • 2003
  • As the continuous casting process is to product slab with high temperature liquid steel, the main role of strand driven roll is to withdraw slab from mold as operator set up casting speed pattern. The strand driven roll in old cast machine is controlled casting speed only. Due to inaccuracies in drive setting up, varying roll diameters, bulging in the product, withdrawal force was distributed irregularly. As a result, because of horizontal crack in slab comer, high casting speed can't be achieved. In this paper, the correlation between the distribution of withdrawal force and slab quality is investigated and the new control algorithm which can be distributed regularly the withdrawal force of strand driven roll is proposed. The principle of proposed algorithm is not to control motor torque directly but to control motor speed reference according to sharing ratio of withdrawal force which is set up in high level controller. The proposed algorithm implemented in POSCO Kwangyang 1-4 continuous casting plant.

Modeling and State Observer Design for Roll Slip in Cold Cluster Mills (냉간압연 다단 압연기의 롤 슬립 모델링 및 상태 관측기 설계)

  • Kang, Hyun Seok;Hong, Wan Kee;Hwang, I Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.12
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    • pp.1543-1549
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    • 2012
  • This study focuses on the state space model and the design of a state observer for the slip dynamics between rolls in STS cold cluster mills. First, a mathematical model of the roll slip is given as a nonlinear differential equation. Then, by using a Taylor series expansion, it is linearized as a state space model. Next, by using Gopinath's algorithm, a minimal-order state observer based on the state space model is designed to estimate the angular speed of all idle rolls except for an actuated roll that is measureable. Finally, a computer simulation is used to validate that the proposed state space model very well describes slip dynamics between, and moreover, the state observer very well estimates the angular speed of the idle roll.

A Study on Improvement of Roll Autopilot System (가로축 자동비행시스템 개선에 관한 연구)

  • Kim, Chong-Sup;Koh, Gi-Oak;Ji, Chang-Ho;Cho, In-Je;Lee, Dong-Kyu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.8
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    • pp.706-711
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    • 2015
  • The fighter aircraft uses several different loading configurations for air-to-surface and air-to-air combat missions. To maintain wings-level flight with an asymmetric weapon configuration, a pilot controls a roll trim system. However, it is difficult to apply an accurate roll trim input for wings-level flight in the actual flight under disturbance. The inaccurate roll trim input degrades the performance of the roll autopilot system. In this paper, to solve this problem, an integrator was additionally designed in the command part of the roll autopilot system. The initial transient response was improved by scheduling the limiter to restrict the roll attitude error. As a result of the evaluation of the simulation for the designed flight control law, the roll attitude following performance was found to be improved in the autopilot system operation under the inaccurate roll trim condition.

Estimation Algorithm of Vehicle Roll Angle and Control Strategy of Roll Mitigation Force Distribution (차량 롤 각 추정 알고리즘 및 롤 저감력 분배 제어 전략)

  • Chung, Seunghwan;Lee, Hyeongcheol
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.6
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    • pp.633-641
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    • 2015
  • The ROM (roll over mitigation) system is a next-generation suspension system that can improve vehicle-driving stability and ride comfort. Currently, mass-produced safety systems, such as ESC (electronic stability control) and ECS (electronic control suspension), enable measurements of longitudinal and lateral acceleration as well as yaw rate through inertial sensor clusters, but they lack direct measurements of the roll angle. Therefore, in this paper, a roll angle estimation algorithm from ESC system sensors and tire normal force has been proposed. Furthermore, this study presents a method for roll over mitigation force distribution between the front and rear of a ROM system. Performance and reliability of the roll angle estimation and roll over mitigation force distribution were investigated through simulations. The simulation results showed that the proposed control algorithm and strategy are reliable during vehicle rollovers.

Load Sharing Control by Following Average Torque Current in Continuous Casting (연속 주조 공정에서 평균 토크전류 추종에 의한 인발력 분배 제어)

  • Chun, Chang-Keun;Kim, Cheul-U
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.3
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    • pp.74-80
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    • 2004
  • If the withdrawal force of strand driven roll which is controlled with predetermined speed isn't distributed regularly in continuous casting process, mold level is changed cyclically and slab quality is not good. In this paper, both casting speed control and load sharing control algorithm of strand driven roll according to ratio which is set up by operator at same time is proposed. The proposed algorithm is to share the withdrawal force by following torque current of each driven roll as average torque current by changing speed reference of each driven roll motor. The load sharing control with anti-wind up for improvement transient state is adopted and the proposed algorithm is implemented in POSCO pilot caster.

A Study on the Application of the Steering Control to Increase Roll Stiffness for the Relatively Tall Vehicles (무게중심이 높은 차량의 롤 강성계수 증대를 위한 스티어링 제어기법의 응용에 관한 연구)

  • 소상균;변기식
    • Journal of the Institute of Convergence Signal Processing
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    • v.4 no.2
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    • pp.53-60
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    • 2003
  • For the high center of gravity vehicles the roll stiffness of their suspensions is arranged to be very high because such vehicles are in some danger of tipping over in cornering. In some cases, the effective roll stiffness is determined significantly by the compliance of the tires because of the very stiff anti-roll members incorporated in the suspension. In such cases, it is clear that the shock absorbers which may be effective in damping heave oscillations have little effect on roll oscillations. Therefore, wind gusts and roadway unevenness may cause large swaying oscillations. In this paper, to improve the stability for the high center of gravity vehicles a control scheme to augment the damping of the roll mode is proposed. As the feedback signals needed to provide damping of the roll motion, the front or rear steer angles or both are chosen because they are very related to roll motion. The scheme is effective from moderate to high speeds and stabilizes the roll mode without introducing disturbance moments from roadway unevenness as shock absorbers do. The validity on the proposed method is verified through the computer simulation.

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An experimental study on the effect of V-ring position and die chamfer shape on the die roll height in fine blanking tool (파인 블랭킹 금형의 V-링 위치 및 다이 챔퍼 형상이 다이 롤 높이에 미치는 영향에 관한 실험 연구)

  • Kim, Jong-Deok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.5
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    • pp.2009-2014
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    • 2012
  • It is very important to minimize the die roll height of gear, in order to maximize the shear cutting surface(tooth surface) of fine blanking. In this paper, the fine blanking tool sets were manufactured in order to study the die roll height according to V-ring position and die chamfer shape. They were constituted of the various die inserts and guide plate inserts with different die chamfer shape and different V-ring distance. The fine blanking experiment was conducted with the fine blanking tool sets and the die roll height of the gear samples was measured. It should be noted that die roll height on the fine blanked gear increased with increasing the V-ring distance and die chamfer angle.

The Launch Vehicle Autopilot Structure Design and Analysis with Roll Compensation Algorithm (롤 보상알고리듬을 적용한 발사체 자세제어기 구조 설계 및 분석)

  • Park, Yong-Kyu;Oh, Choong-Seok;Sun, Byung-Chan;Roh, Woong-Rae
    • Aerospace Engineering and Technology
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    • v.10 no.1
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    • pp.98-106
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    • 2011
  • This paper is summarized for designing launch vehicle autopilot structure with attitude angle command from guidance algorithm and for evaluating performance of autopilot using launch vehicle six-degree of freedom simulation program. The suggested autopilot has heritage from KSR-III/KSLV-I upper stage autopilot designing experience, and it has two design point. The one is, it must have same performance with KSR-III/KSLV-I upper stage autopilot, the other is, it must be simple autopilot structure and use low number of variable to apply on-board system. It is evaluated the performance using launch vehicle six-degree of freedom simulation program in case of roll maneuvering and no roll control flight condition.