• Title, Summary, Keyword: yawing error

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A Study on the Feeding System of Centerless Grinder for Machining the Ferrule (페룰가공용 무심연삭기 이송계 개발)

  • 박천홍;황주호;조순주
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.65-69
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    • 2002
  • In order to practicalize high precision centerless grinder for machining the ferrule, its feeding system is designed and tested. For satisfying the desired diametric tolerance and cylindricity of the ferrule, the feeding system is designed to have relatively high axial stiffness of 600 N/$\mu\textrm{m}$, high angular motion accuracy of 0.5 arcsec/mm in yaw direction and minimum resolution of 0.05 $\mu\textrm{m}$. A prototype of feeding system is built up with hydrostatic guideway and ballscrew. A linear scale with 0.05 $\mu\textrm{m}$ of resolution is used for position feedback. Experimental results show that the feeding system has the infinity of axial stiffness within the range of 1000 N and 0.3 arcsec/mm of yawing error. Also the feeding system shows obvious step response against 0.05 $\mu\textrm{m}$/step command without the lost motion or backlash. Although the vertical stiffness is reduced to 440 N/$\mu\textrm{m}$ by the elastic deformation of rail, it is good enough to use for machining the ferrule. From above, it is confirmed that the feeding system is applicable to centerless grinder for machining the ferrule.

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Analysis of Mechanical Loads During Yawing (풍력터빈 요 운동에 대한 기계적 하중 해석)

  • Nam, Yoon-Su;Choi, Han-Soon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.5
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    • pp.487-495
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    • 2012
  • The yaw control, a major part of the wind turbine, is closely related to the efficiency of electric power production and the mechanical load. The yaw error, which results from the nacelle not being appropriately aligned in the wind direction, not only decreases the power output but also reduces the lifetime of the wind turbine as a result of large fatigue loads. However, the yawing rate cannot be increased indefinitely because of constraints on mechanical loads. This paper investigates the characteristics of an active yaw control system, the basic principle of the system, and mechanical loads around the yaw axis during yawing.

A Measurement Error Correction Algorithm of Road Image for Traveling Vehicle's Fluctuation Using V.F. Modeling (V.F. 모델링을 이용한 주행차량의 진동에 대한 도로영상의 계측오차 보정 알고리듬)

  • Kim Tae-Hyo;Seo Kyung-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.8
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    • pp.824-833
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    • 2006
  • In this paper, the image modelling of road's lane markings is established using view frustum(VF) model. From this model, a measurement system of lane markings and obstacles is proposed. The system also involve the real time processing of the 3D position coordinate and the distance data from the camera to the points on the 3D world coordinate by virtue of the camera calibration. In order to reduce their measurement error, an useful algorithm for which analyze the geometric variations due to traveling vehicle's fluctuation using VF model is proposed. In experiments, without correction, for instance, the $0.4^{\circ}$ of pitching rotation gives the error of $0.4{\sim}0.6m$ at the distance of 10m, but the more far distance cause exponentially the more error. We con finned that this algorithm can be reduced less than 0.1m of error at the same condition.

Measurement of 5 DOF Motion Errors in the Ultra Precision Feed Tables for Error Compensation (오차보정을 위한 초정밀 테이블의 5 자유도 운동오차 측정)

  • 오윤진;박천홍;이득우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.672-676
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    • 2004
  • In this paper, measuring system of 5 DOF motion errors are proposed using two capacitive type sensor, a straight edge and a laser interfoerometer. Yawing error and pitching error are measured using the laser interferometer, and rolling error is measured by the reversal method using a capacitive type sensor. Linear motion errors of horizontal and vertical direction are measured using the sequential two point method. In this case, influence of angular motion errors is compensated using the previously measured angular motion errors. In the horizontal direction, measuring accuracy is within 0.05 $\mu$m and 0.27 arcsec, and in the vertical direction, it is within 0.15 $\mu$m and 0.5 arcsec. From these results, it is confirmed that the proposed measureing system is very effective to the measurement of 5 DOF motion errors in the ultra precision feed tables.

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The Couplings for ball-screw on high precision positioning (고정도 이송을 위한 공기정압커플링에 관한 연구)

  • 황성철;전도현;이득우
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.161-166
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    • 2002
  • Recently, researches on precision machining of nato-order, especially in the field of optical components and semi-conductors have been under development very actively. A accuracy of machining and positioning in a critical issue in ultra-precision machining. This paper proposes a new positioning system which can give excellent dynamic characteristics and reduce errors in horizontal, vertical, pitching, and yawing motions. In this paper, we suggest a connecting mechanism (the couplings) to reduce motion errors such as chatter and runout while preserving the positioning accuracy. We verified the good performance in the new connecting systems with various coupling types, which we classified into the fixed type, the spring type, the aeroctatic-nozzle type, and the aeroctatic-porous type according to the way of reducing the chatter and error.

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A Precision Position Control of Antenna Driving System in Naval Vessel (함상 안테나 구동용 안정화장치의 정밀 위치제어)

  • Cho, Taik-Dong;Seo, Song-Ho;Nam, Ki-Jung
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.4
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    • pp.190-196
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    • 2001
  • The naval vessel must moves rolling, pitching, yawing by wave when it runs in ocean. Some narrow beam antenna needed position compensation by stabilizer or gimbal for best performance. This paper presents the precision position control for heavy weight(130kg) in roll and pitch direction. Generally it's called for gimbal. This gimbal uses P-I controller, and it's driven by linear actuator and servo motor. This gimbal gets ship's gyro signal and synchro, which have the absolute angle value. Some other similar equipments are driven by huge hydraulic power, but this gimbal is driven by small servo motor. This control loop gets the following procedure repeatedly; reading ship gyro and gimbal synchro, calculating compensated error and control output, driving motor and actuator The performance of gimbal system was satisfied.

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Performance Estimation for Shipboard Directional Pedestal by Using M&S Methodologies (M&S기법을 활용한 선박용 지향성 요동보상장치 성능 분석)

  • Lee, Sungkyun;Go, Jinyong;Han, Yongsu;Kim, Changhwan
    • IEMEK Journal of Embedded Systems and Applications
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    • v.13 no.6
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    • pp.297-303
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    • 2018
  • Recently, the tasks assigned to surface ship are becoming diverse and important. In this trend, shipboard directional pedestals are widely used for surveillance and electronic warfare because ships are always under angular motion such as rolling, pitching and yawing. To estimate the performance of pedestal, the motion responses of vessel as well as mechanical characteristics of pedestal should be considered. In this study, both the motion responses of vessel which the pedestal will be mounted and the behavior of 3-axis pedestal are considered. Numerical analysis based on potential theory is used to obtained motion characteristics of vessel and then 6-DOF motions of vessel are simulated under operational condition. 1st-order time delay model and LQR control algorithm are used for modeling of pedestal drive model and control model, respectively. By using coordinate transform, the angular motions which the pedestal should compensate are calculated from the vessel's angular motion. Through these M&S methodologies, time history of pedestal behavior and maximum angular error of each pedestal axis are obtained. Overall M&S results show that 3-axis pedestal compensate the angular motion induced by vessel, efficiently.

Loads of NREL Phase VI Rotor at Hub in Yawed Conditions (요 상태에서 NREL Phase VI 로터의 허브 중심 하중 예측)

  • Ryu, Ki-Wahn
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.12
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    • pp.841-847
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    • 2019
  • Time series data of 6-component loads were computed for a horizontal axis wind turbine rotor in yawed operating conditions with both rotating and non-rotating coordinate systems fixed at a center of a rotor hub. In this study, a well-known 20 kW class of the NREL Phase VI rotor was used for a model wind turbine, and this paper focuses on the yaw moments and over-turning moments for the operating wind speed range between 6 to 25 m/s. Unsteady blade element momentum theorem was adopted to get the aerodynamic loads acting on the wind turbine rotor. Computed 6-component loads using the developed UBEM code were compared with those using the NREL FAST program. From the computed results, both yaw and over-turning moments would be basic inputs to determine not only the specification of yawing mechanism but also the design condition of foundation.

A Study on the Wireless Ship Motion Measurement System Using AHRS (AHRS를 이용한 무선 선체 운동 측정 시스템에 관한 연구)

  • Kim, Dae-Hae;Lee, Sang-Min;Kong, Gil-Young
    • Journal of Navigation and Port Research
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    • v.37 no.6
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    • pp.575-580
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    • 2013
  • The IMU(Inertial Measurement Unit) which is the expensive equipment has been used as a special limited area, usually in measurement of posture of applying to the areas of ship, submarine, aircraft and military equipment application. However, in the current situation, MEMS AHRS technology can replace the high-priced IMU in MEMS AHRS selected application field. In this paper, wireless hull motion measurement system was suggested for measuring key elements of ship's movement such as rolling, pitching and yawing using gyro, acceleration and magnetic sensors of AHRS. In order to reduce the error such as instantaneous acceleration, effects and vibration of geomagnetic, we have adopted the sensors equipped with Kalman filtering. The Wireless hull motion measurement system using AHRS sensors was tested in actual ship and it could easily be applied in limited installation circumstances of the ship. In the future, this system can be useful in the navigation safety and marine accident analysis by using with ship equipment such as INS or VDR in the maritime.