• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.4
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• pp.44-48
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• 2006

Recently, demand the ultra precision product which is increasing rapidly is used extensively frontier industry field such as semi-conductor, computer, aerospace, precision machine. Ultra precision processing is the portion that is very needed to NT in the field of mechanical engineering. The latest date, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts those are connected with these industrial fields. Specially, require motion accuracy of high resolution of nm order in stroke of hundreds millimeters according as diameter of processing object great and processing accuracy rises. In this case ,the response speed absolute delay because inertial mass of moving part is very large. Therefore, real time motion error compensation becomes very hardly. In this paper, we used ultra precision cutting unit(UPCU) to cope such problem. a UPCU is designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error is compensated for real time using a UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2263-2268
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• 2010

In this paper, the hybrid compensation algorithm($A_{HB}$) for localization using the Compensation Algorithm distance($CA_d$) and the Algorithm of Equivalent Distance Rate(AEDR) in SDS-TWR(Symmetric Double-Sided Two-Way Ranging) is suggested and the performance of the proposed algorithm is analyzed by practical experimentations. From experimentations, it is confirmed that the errors are reduced in 28 coordinates of total 32 coordinates in the experimental region and the errors are reduced about above 70% in the assigned 3 type error level ranges by $A_{HB}$. Also, it is analyzed that the average localization error is reduced from 2.67m to 1.19m as 55.4% in total 32 coordinates by $A_{HB}$ and the error compensation capability of $A_{HB}$ is very excellent as above 90%. From above results, we have seen that the error reduction ratio and error compensation capability of $A_{HB}$ is more excellent than each $CA_d$ or AEDR.

• The Journal of the Acoustical Society of Korea
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• v.13 no.5
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• pp.40-50
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• 1994

In this paper, the sensitivity compensation method for three-dimensional acoustic intensity probe in the higher frequency range has been studied. The measurement error in the higher frequency range is generated from the phase mismatch between microphone's signals of the probe. If the wavelength of sound signal measured is less than those of the distance between microphones of the probe, that is, the higher frequency of the sound signal, the bigger measurement error is generated. In this study, we proposed the compensation methods for one-dimensional acoustic intensity probe with two-microphones, and the efficiency of those methods were investigated by numerical calculation of computer. It was most effective method to compensate the phase mismatch between microphone for the acoustic intensity probe was investigated for the sound estimated. and the efficiency of this method in a three-dimensional probe was investigated for the sound wave travelling in the arbitrary direction by numerical calculation of computer. In this result, the efficiency was proved that, for the measurement error of 1dB or less with the three-dimensional probe of 60mm space, the frequency should be less than 1.2kHz without the error compensation method, but the frequency increased up to 2.8kHz with the error compensation method.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.59-64
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• 2004

In this paper, the error compensation method of the low-cost IMU is proposed. In general, the position and attitude error calculated by accelerometers and gyros grows with time. Therefore the additional information is required to compensate the drift. The attitude angles can be bound accelerometer mixing algorithm and the heading angle can be aided by single antenna GPS velocity. The Kalman filter is used for error compensation. The result is verified by comparing with the attitude calculated by Attitude Heading Reference System with Micro Electro Mechanical System for a basis

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.943-946
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• 2000

Selective laser sintering(SLS) is a solid freeform fabrication process whereby a part is built layerwise by scanning a powder bed. The properties of metal powder are dependent on the heat, it is not easy to do the exact error compensation with analysis and estimation by modeling. This paper suggests that the error is compensated by experimental method and then the accuracy of shape is enhanced by revising of STL file. Also bonding force is measured by an experiment with change of process path.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.310-312
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• 2009

The heterodyne laser interferometer has been widely used in precise measurement field. However, the accuracy is limited by the nonlinearity error caused from incomplete laser sources and nonideal optical components. In this paper, we propose the Dual-EKF which estimates states and weights simultaneously to improve the resolution of heterodyne laser interferometer. As a proof, we demonstrate the effectiveness of our proposed method through experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.152-160
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• 2001

Six degrees of freedom measurement systems are required in many fields: Precision machine control. precision assembly, vibration analysis, and so on. This paper presents a new six degrees of freedom measurement system utilizing typical features of a diffraction grating. It is composed of a laser source, three position sensitive detectors, a diffraction grating target, and several optical components. Six degrees of freedom displacement is calculated kinematically from the coordinates of diffracted rays on the detectors. Optical measurement error was caused by the fact that a laser source had a Gaussian intensity distribution. This error was analyzed and compensated using simple equations. The performance of the compensation equation was verified in the experiment. The experimental results showed that the compensation equation could reduce the optical measurement error remarkably and the error in six degrees of freedom measurement less than $\pm$10$\mu$m for translation and $\pm$0.012$^{\circ}$for rotation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.391-397
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• 2018

This paper proposes a interpolation error compensation method for PMSM torque control. In PMSM torque control, two dimensions look-up table(2D-LUT) is used for current reference generation due to its stable and robust torque control performance. However, the stored data in 2D-LUT is discreet, it is impossible to store all over the operation range. To reduce the reference generation error in this region, the 2D-Interpolation method is conventionally used, however, this method still remains the error affected by the number of stored data. Besides, in the case stored by fixed unit, this error is increased in field weakening region because of the small number of stored data. In this paper, analyzing the cause of this interpolation error, and compensating the method to reduce this error. Proposed method is verified by the simulation and experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.409-412
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• 2002

This paper presents a measurement method to compromise surface error in surface machining processes. In order to compromise the surface error in machining process, on-machine measurement is essential. There are two kinds of on-machine measurement methods available to measure the surface errors in flat workpieces: i.e., surface scanning method and sensor scanning method. However, motion errors are inevitably engaged in both methods. This paper proposes a new idea to measure the surface error for error compensation. The measurement system consists of a laser, a CCD camera and processing system, a carrier system with a stylus, and some optical units. The experimental results show that the proposed method is useful to compensate the surface errors of machined workpieces.

• Journal of the Korean Solar Energy Society
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• v.29 no.6
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• pp.22-31
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• 2009

Canting is the optical alignment of mirror facets of heliostat such that the heliostat could focus the energy as a unit concentrator. Canting could improve the optical performance of heliostat and thus improves the efficiency of heliostat and ultimately improves the efficiency of the solar thermal power plant. This study discusses the effect of mirror canting, especially off-axis canting, used to compensate the sun tracking error caused by the heliostat geometrical errors. We first show that the canting could compensate the sun tracking error caused by the heliostat geometrical errors. Then we show that the proper canting time could exist, depending on the heliostat location. Finally we show how much the sun tracking performance could be improved by canting, by providing RMS sun tracking error. The limitation and caution of using canting to improve the sun tracking performance are also discussed.