• 제목/요약/키워드: linear motion error

검색결과 207건 처리시간 0.03초

리니어모터를 이용한 초정밀 유정압안내면 개발 (Development of a Hydrostatic Guideway Driven by the Linear Motor)

  • 박천홍;황주호;오윤진;이찬홍
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.343-346
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    • 2003
  • In order to discuss the availability of the hydrostatic guideway driven by the coreless linear motor to ultra precision machine tools, a prototype of guideway is designed and tested in this research. A coreless linear DC motor with the continuous force of 156 N and a laser scale with the resulution of 10 nm are used as the feeding system. The experiments are performed on the static stiffness. motion accuracy, positioning accuracy. microstep response and variation of velocity. The guideway has the infinite axial stiffness within 50 N of applied load, and has 0.08 ${\mu}{\textrm}{m}$ of linear motion error and 0.1 arcsec of angular motion error. It also has 0.21 ${\mu}{\textrm}{m}$ of positioning error and 0.09 ${\mu}{\textrm}{m}$ of repeatability, and it shows the stable response against the 10 nm resolution step command. The velocity variation of feeding system is less than 5%. From these results, it is confirmed that the hydrostatic guideway driven by the coreless linear motor is very useful for the ultra precision machine tools.

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Experimental Verification on the Corrective Machining Algorithm for Improving the Motion Accuracy of Hydrostatic Bearing Tables

  • Park, Chun-Hong;Lee, Chan-Hong;Lee, Husang
    • International Journal of Precision Engineering and Manufacturing
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    • 제5권3호
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    • pp.62-68
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    • 2004
  • Effectiveness of a corrective machining algorithm, which can construct the proper machining information to improve motion errors utilizing measured motion errors, is verified experimentally in this paper, Corrective machining process is practically applied to single and double side hydrostatic bearing tables. Lapping process is applied as a machining method. The machining information is obtained from the measured motion errors by applying the algorithm, without any information on the rail profile. In the case of the single-side table, after 3 times of corrective remachining, linear and angular motion errors are improved up to 0.13 $\mu\textrm{m}$ and 1.40 arcsec from initial error of 1.04 $\mu\textrm{m}$ and 22.71 arcsec, respectively. In the case of the double-side table, linear and angular motion error are improved up to 0.07 /$\mu\textrm{m}$ and 1.42 arcsec from the initial error of 0.32 $\mu\textrm{m}$ and 4.14 arcsec. The practical machining process is performed by an unskilled person after he received a preliminary training in machining. Experimental results show that the corrective machining algorithm is very effective and easy to use to improve the accuracy of hydrostatic tables.

혼합축차이점법을 이용한 진직도 정밀측정에 있어서 센서 게인오차의 영향에 관한 연구 (A Study on the Effect of the Sensor Gain Error in the Precision Measurement of Straightness Error Using Mixed Sequential Two-Probe Method)

  • 정지훈;오정석;김경호;박천홍
    • 한국정밀공학회지
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    • 제30권6호
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    • pp.607-614
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    • 2013
  • In this study, effect of the sensor gain error is theoretically analyzed and simulated when mixed sequential two-prove method(MTPM) is applied for the precision measurement of straightness error of a linear motion table. According to the theoretical analysis, difference of the gain errors between two displacement sensors increases measurement error dramatically and alignment error of the straightedge is also amplified by the sensor gain difference. On the other hand, if the gain errors of the two sensors are identical, most of error terms are cancelled out and the alignment error doesn't give any influence on the measurement error. Also the measurement error of the straightness error is minimized compared with that of the straightedge's form error owing to close relationship between straightness error and angular motion error of the table in the error terms.

Minimization of Modeling Error of the Linear Motion System with Voice Coil Actuator

  • Hwang, Jin-Dong;Kwak, Yong-Kil;Jung, Hong-Jung;Kim, Sun-Ho;Ahn, Jung-Hwan
    • International Journal of Control, Automation, and Systems
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    • 제6권1호
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    • pp.54-61
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    • 2008
  • This paper presents a method for reducing modelling error in the linear motion system with voicecoil actuator (VCA). A model of linear motion system composed of a mechanism and control was prepared to verify the proposed method. In modeling of the system, the damping coefficient obtained experimentally is applied to the model in order to consider the effect of the viscous friction for the moving part in VCA. The response velocity of VCA for duty ratio of PWM signal was analyzed in the time domain. Consequently, the relation between velocity and duty ratio was obtained. The result from the experiment showed an error of 9% when compared with that of simulation. In order to reduce the modeling error, impedance variation according to input frequency was analyzed, and equivalent impedance with multi-frequency was applied to the control part. As a result, the modeling error decreased to 5%.

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

  • 오윤진;박천홍;이득우
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2004년도 추계학술대회 논문집
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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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부하를 고려한 직선운동유니트의 정밀도 시뮬레이션 기술 (Simulation of Motion Accuracy Considering Loads in Linear Motion Units)

  • 김경호;박천홍;오정석
    • 한국정밀공학회지
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    • 제32권5호
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    • pp.405-413
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    • 2015
  • This paper presents the motion accuracy simulation considering loads such as workpiece weight, cutting force, cogging force of a linear motor, and force caused by misalignment and runout error of a ballscrew in linear motion units. The transfer function method is basically utilized to estimate 5-DOF motion errors, together with the equilibrium equations of force and moment on the table. The transfer function method is modified in order to consider clearance changed according to the loads in the double sided hydrostatic/aerostatic bearings. Then, the analytic model for predicting the 5-DOF motion errors is proposed with the modified transfer function method. Motion errors were simulated under different loading conditions in the linear motion units using hydrostatic, aerostatic, and linear motion bearings, respectively. And the proposed analytic model was verified by comparing the estimated and measured motion errors.

다공질 공기베어링 테이블의 운동오차 해석 (Motion Error Analysis of an Porous Air Bearing Table)

  • 박천홍;이후상
    • 연구논문집
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    • 통권34호
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    • pp.101-112
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    • 2004
  • In order to analyze the motion errors of the aerostatic stage, it is necessary to consider the influence of the moment variation occurredinside the pads. In this paper, a motion error anaysis method utilizing the transfer functions on the reaction force and moment is proposed, and general characteristics of the transfer functions are discussed. Calculated motion errors by the proposed method show good agreement with the ones calculated by Multi Pad Method, which is considered the entire table as an analysis object. Also, by the introduction of the transfer function of motion errors, which represent the relationship between the spatial frequency components of the rail form error and motion errors, motional characteristics of the porous aerostatic stage can be generalized. In detail, the influence of the spatial frequencies is analyzed quantatively, and the patterns of the insensitive frequencies which almost do not affect the linear motion error or angular motion error according to the rail length ratio and the number of the pad are verified. The relationship between the moment variation occurred inside the pads and the motion errors is also verified together.

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전달함수를 이용한 다공질 공기베어링 스테이지의 운동오차해석 (Motion Error Analysis of the Porous Air Bearing Stages Using the Transfer Function)

  • 박천홍;이후상
    • 한국정밀공학회지
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    • 제21권7호
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    • pp.185-194
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    • 2004
  • In order to analyze the motion errors of the aerostatic stage, it is necessary to consider the influence of the moment variation occurred inside the pads. In this paper, a motion error analysis method utilizing the transfer functions on the reaction force and moment is proposed, and general characteristics of the transfer functions are discussed. Calculated motion errors by the proposed method show good agreement with the ones calculated by Multi fad Method, which is considered the entire table as an analysis object. Also, by the introduction of the transfer function of motion errors, which represent the relationship between the spatial frequency components of the rail form error and motion errors, motional characteristics of the porous aerostatic stage can be generalized. In detail, the influence of the spatial frequencies is analyzed qualitatively, and the patterns of the insensitive frequencies which almost do not affect the linear motion error or angular motion error according to the rail length ratio and the number of the pad are verified. The relationship between the moment variation occurred inside the pads and the motion errors is also verified together.

유정압테이블 수정가공 알고리즘의 실험적 검증 (Experimental Verification on Corrective Machining Algorithm of Hydrostatic Table)

  • 박천홍;이찬흥;이후상
    • 한국정밀공학회지
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    • 제19권6호
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    • pp.70-76
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    • 2002
  • Effectiveness of corrective machining algorithm is verified experimentally in this paper by performing corrective machina work practically to single side and double sides hydrostatic tables. Lapping is applied as machining method. Machining information is calculated from measured motion errors by applying the algorithm, without information on rail profile. It is possible to acquire 0.13$\mu$m of linear motion error, 1.40arcsec of angular motion error in the case of single side table, and 0.07$\mu$m of linear motion error, 1.42arcsec of angular motion error in the case of double sides table. The experiment is performed by an unskilled person after he experienced a little of preliminary machining training. Experimental results show that corrective machining algorithm is very effective, and anyone can improve the accuracy of hydrostatic table by using the algorithm.

LuGre Model-Based Neural Network Friction Compensator in a Linear Motor Stage

  • Horng, Rong-Hwang;Lin, Li-Ren;Lee, An-Chen
    • International Journal of Precision Engineering and Manufacturing
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    • 제7권2호
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    • pp.18-24
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    • 2006
  • This paper proposes a LuGre Model-Based Neural Network (MBNN) friction compensation algorithm for a linear motor stage. For matching the friction phenomena in both the motion-start region and the motion-reverse region, the LuGre dynamic model is employed into the proposed compensation algorithm. After training of the model-based neural network is completed, the estimated friction for compensation is obtained. From the obtained result we find that the new structure gains advantage over the non-friction compensation system on the performance of the compensator in both regions. The proposed compensator is evaluated and compared experimentally with an uncompensated system on a microcomputer controlled linear motor tracking system in the final section of the paper. The experimental results show the improvement on the maximum velocity error and the root mean square tracking error in the motion-start region ranges from 34% to 53% and from 53% to 75% respectively, and in the motion-reverse region from 48% to 65% and from 79% to 90% respectively.