• Title/Summary/Keyword: linear motion error

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A Study on the Errors in the Free-Gyro Positioning and Directional System (자유자이로 위치 및 방위시스템의 오차에 관한 연구)

  • Jeong, Tae-Gweon
    • Journal of Navigation and Port Research
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    • v.37 no.4
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    • pp.329-335
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    • 2013
  • This paper is to develop the position error equations including the attitude errors, the errors of nadir and ship's heading, and the errors of ship's position in the free-gyro positioning and directional system. In doing so, the determination of ship's position by two free gyro vectors was discussed and the algorithmic design of the free-gyro positioning and directional system was introduced briefly. Next, the errors of transformation matrices of the gyro and body frames, i.e. attitude errors, were examined and the attitude equations were also derived. The perturbations of the errors of the nadir angle including ship's heading were investigated in each stage from the sensor of rate of motion of the spin axis to the nadir angle obtained. Finally, the perturbation error equations of ship's position used the nadir angles were derived in the form of a linear error model and the concept of FDOP was also suggested by using covariance of position error.

Development of an Accuracy Simulation Technology for Mechanical Machines (기계장비 정밀도 시뮬레이션 기술 개발)

  • Park, Chun-Hong;Hwang, Joo-Ho;Lee, Chan-Hong;Song, Chang-Gyu
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.3
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    • pp.259-264
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    • 2011
  • Authors are carrying out a national project which develops an accuracy simulation technology of mechanical machines to predict the stiffness and accuracy of machine components or entire machine in the design stage. Analysis methods in this technology are generalized to achieve the wide applicability and to be utilized as a web based platform type. In this paper, outline of the project such as concept, aim and configuration is introduced. Contents of the research are also introduced, which are composed of four main research fields; structural dynamics, linear motion analysis, rotary motion analysis and control and vibration analysis. Finally, a future plan is presented which is made up with three stages for the advance toward an ultimate manufacturing tools.

High Performance CNC Control Using a New Discrete-Time Variable Structure Control Method (새로운 이산시간 가변구조 제어방법을 이용한 CNC의 고성능 제어)

  • Oh, Seung-Hyun;Kim, Jung-ho;Cho, Dong-il
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.12
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    • pp.1053-1060
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    • 2000
  • In this paper, a discrete-time variable structure control method using recursively defined switching function and a decoupled variable structure disturbance compensator is used to achieve high performance circular motion control of a CNC machining center. The discrete-time variable structure control with the decoupled disturbance compensator method developed in this paper uses a recursive switching function defined as the sum of the current tracking error vector and the previous value of the switching function multiplied by a positive constant less than one. This recursive switching function provides much improved performance compared to the method that uses a switching function defined only as a linear combination of the current tracking error. Enhancements in tracking performance are demonstrated in the circular motion control using a CNC milling machine.

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SOFTWARE LINEAR AND EZPONENTIAL ACELERATION/DECELERTION METHODS FOR INDUSTRIAL ROBOTS AND CNC MACHINE TOOLS

  • Kim, Dong-Il;Song, Jin-Il;Lim, Yong-Gtu;Kim, Sungkwun
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10b
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    • pp.1904-1909
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    • 1991
  • Software linear and exponential acceleration/deceleration algorithms for control of machine axes of motion in industrial robots and CNC machine tools are proposed. Typical hardware systems used to accelerate and decelerate axes of motion are mathematically analyzed. Discrete-time state equations are derived from the mathematical analyses for the development of software acceleration/deceleration algorithms. Synchronous control method of multiple axes of motion in industrial robots and CNC machine tools is shown to be easily obtained on the basis of the proposed acceleration/deceleration algorithms. The path error analyses are carried out for the case where the software linear and exponential acceleration/deceleration algorithms are applied to a circular interpolator. A motion control system based on a floating point digital signal processor (DSP) TMS 320C30 is developed in order to implement the proposed algorithms. Experimental results demonstrate that the developed algorithms and the motion control system are available for control of multiple axes and nonlinear motion composed of a combination of lines and circles which industrial robots and CNC machine tools require.

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The Organization of Measuring Systems of Linear Cycle Plane Positioning Accuracy on NC Lathes (NC 선반에서 직선 사이클 평면 위치결정 정도 측정 시스템의 구성)

  • 김영석;김재열;송인석;곽이구;정정표;한지희
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2002.10a
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    • pp.387-392
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    • 2002
  • It is very important to measure linear cycle plane positioning accuracy of NC lathes as they affect those of all other machines machined by them in industries. For example, if the linear cycle plane positioning accuracy of each axes directions is bad, the accuracy of works will be wrong and the change-ability will be bad in the assembly of machine parts. In this paper, computer software systems are organized to measure linear displacements of ATC(Automatic tool changer) of NC lathes using linear scale and time pulses comming out from computer in order to get data at constant time intervals from the sensors. And each sets of error data gotten from the test is expressed to plots by computer treatment and the results of linear cycle plane positioning error motion estimated to numerics by statistical treatments.

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Design of the Estimator of Forward Kinematics Solution for a 6 DOF Motion Bed (6자유도 운동재현용 베드의 순기구학 추정기 설계)

  • 강지윤;김동환;이교일
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.04a
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    • pp.483-487
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    • 1996
  • We consider the estimation of the position and orientation of 6 DOF motion bed (Stewart platform) from the measured cylinder length. The solution of forward kinematics is not solved yet as a useful realtime application tool because of the complity of the equation with multiple solutiple solutions. Hence we suggest an algorithm for the estimation of forward kinematics solution using Luenberger observer withnonlinear error correction term. The Luenberger observer withlinear model shows that the estimation error does not go to zero in steadystate due to the linearization error of the dynamic model. Hence the linear observer is modified using nonlinear measurement error equation and we prove thd practical stability of the estimation error dynamics of the proposed observer using lyapunov function.

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A Study on Measuring of Motion Accuracy of NC Machine Tools(No.1) -about Measuring of Linear Cycle Positioning Accuracy of NC Lathe (NC 공작기계의 운동정도 측정에 관한 연구(제1보) - NC 선반의 직선 사이클 위치결정정도 측정에 관하여 -)

    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.7 no.1
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    • pp.82-88
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    • 1998
  • It is very important to test linear cycle positioning accuracy of NC lathes as it affect all other machines machined by them in industries. For example, if the linear positioning accuracy of x or z-axis directions is bad, the size of works will be wrong and the change-ability will be bad in the assembly of machine parts. In this paper , measuring systems are organized to measure linear displacement of ATC(Automatic tool changer) of NC lathe using laser interferometer, magnescale and tick pulses coming out from computer in order to get data at constant time intervals from the sensors, And each set of data gotten from test is expressed to a plots by computer treatment and the results of linear positioning error motion is estimated to numerics by statistical treatments.

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Force Characteristic Analysis of Linear Motor to Reduce Manufacturing Error in A Linear Motion Machine Tool (선형 운동 공작기계의 가공오차 저감을 위한 리니어 모터의 힘 특성 해석)

  • Cho, Han-Wook;Han, Cheol;Choi, Jang-Young;Choi, Sang-Gyu;Park, Cheol-Ho;Jang, Seok-Myeong
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.1081-1082
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    • 2011
  • In order to predict the accuracy of the linear motion machine tools, the force characteristics such as the detent force, the attraction force and the moment are estimated by analytical method or FEM. In this paper, we proposed the analytical calculation process for the force characteristics of a linear motor. The analytical results are good agreement with FEM one. They could be used for the precision prediction simulator with the information of linear bearings, encoders, etc.

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A study on Measuring of Motion Accuracy of NC Machine Tools(No. 2) - about Measuring of Linear Cycle Positioning Accuracy of Machining Center - (NC 공작기계의 운동정도 측정에 관한 연구(제2보) -머시닝 센터의 직선 사이클 위치결정정도 측정에 관하여-)

  • Kim, Yeong Seok
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.7 no.3
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    • pp.51-51
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    • 1998
  • It is very important to test linear cycle positioning accuracy of Machining centers as it affect all other machines machined by them in industries. For example, if the linear positioning accuracy of each axes directions is bad, the size of works will be wrong and the change-ability will be bad in the assembly of machine parts. In this paper, measuring systems are organized to measure linear displacements of table or spindle of machine center using laser interferometer, magnescale and tick pulses comming out from computer in order to get data at constant time intervals from the sensors. And each set of data gotten from test is expressed to a plots by computer treatment and the results of linear positioning error motion is estimated to numerics by statistical treatments.

A dynamic selection of advanced prediction mode in H.263 encoder using error distribution of motion estimation (움직임 추정 오차 분포를 이용한 H.263 부호화기의 진보 예측 모드의 동적 선택)

  • 허태원;이근영
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.5
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    • pp.94-102
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    • 1998
  • In this paper, we proposed a dynamic selection scheme of advnaced prediction mode(DAPM), which reduces computational cost and improves coding efficiency. We can select the mode between default prediction mode (DPM) and advanced prediction mode (APM) according to motion componenets in a frame dynamically. For this purpose, we defined error distribution of motion estimation (EDME) as sum of absolute difference(SAD) for each searching points. This distribution region is divided to four subregions. We calculate minimum values in each subregions and then, we determine whether block motion estimation is performed or not depending on the results. As a result, we reduced computational complexity to 30% without degradation of image quality compared to fixed APM(FAPM) by selecting DPM for linear movement.

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