• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.345-346
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• 2007

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.154-162
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• 1997

A real time error compensation system was developed to improve the quasistatic volumetric accuracy of a machining center by using sensing, metrology, modeling, and computer control techniques. Including thermal errors, 32 error components are formulated in the time-space domain. Fifteen thermal sensors are used to characterize the temperature field of the machine. A compensation controller based on the IBM/PC has been linked with a CNC controller to compensate for machine errors in real time. The maximum linear displacement error in 4 body diagonals were reduced from 140 ${\mu}m$ to 34.5${\mu}m$ with this compensation system, and the spindle thermal drift in space was reduced from 147.3 ${\mu}m$ to 16.8 ${\mu}m$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.375-379
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• 1997

Thermal drift of the machine tool spindle due to temperature increase dominates the major source of the machine tool error. To compensate the thermal errors, software based error correction methods could be implemented. In th~s case, we need model to map the relationship between temperature and thermal distortion. Traditionally, two or three different methods have been trled: step increase of spindle speed, constant, random. The latter two methods are described in the document of ISOlDIS230-3. In this research, three different methods were verified through the experiments from the viewpoint of compensation of thermal distortion. Constant spindle speed turned out good enough for monitoring the behavior of the thermal drift and modeling the relationship between temperature and thermal distortion.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.453-457
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• 2001

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric and thermal errors of the machine tools. In this study, the compensation device is manufactured in order to compensate thermal error of machine tools under the real-time. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to compensate thermal characteristics under several operating conditions, experiments performed with five gap sensors and manufactured compensation device on the horizontal machining center.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.16-23
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• 2004

Thermally induced errors of machine tools have been recognized as one of the most important issues in precision machining. This is probably the most formidable obstacle to obtain high level of machining accuracy. To this regard, the experimental compensation methodologies such as software-based method or origin shift of machine tool axes have been suggested. In this research, to cope with thermal deformation, a model based correction was carried out with the function of an external machine coordinate shift. Models with multi-linear regression or neural network were investigated to selected a good one for thermal compensation. Consequently, multi-linear regression model combined with origin shift was verified good enough form the machining of dot matrices of plate with ball end milling.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.214-219
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• 2001

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. In this study, the compensation device and temperature-based algorithm have been presented in order to compensate thermal error of machine tools under the real-time. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball artifact, and five gap sensors. In order to compensate thermal characteristics under several operating conditions, experiments performed with five gap sensors and manufactured compensation device on the horizontal machining center.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.70-75
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• 2001

In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindel unit which are measured by the touch probe unit with a star type styluses, a designed spherical ball arti-fact, and five gap sensors. In order to analyze the thermal characteristics under several operating conditions, experiments performed with the touch probe unit and five gap sensors on the vertical and horizontal machining centers.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.402-409
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• 2022

In vector-controlled drive systems, the current measurement offset error causes unwanted torque ripple, resulting in speed and torque control performance degradation. The current measurement offset error is caused by various factors, including thermal drift. This study proposes a simple DC offset error compensation method for a surface permanent magnet motor based on a disturbance observer. The disturbance observer is designed in the stationary reference frame. The proposed method uses only the measured current and machine parameters without additional hardware. The effect of parameter variations is analyzed, and the performance of the current measurement offset error compensation method is validated using simulation and experimental results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.4 no.3
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• pp.28-33
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• 1967

The analysis of differential amplifier is simplified by the extention of bisection theorem. In order to reduce the thermal and porwor drifts, a self compensating circuit is employed. The optimum conditions of the self compensating circuit are: the base-emitter voltage of one transistor should be equal to the other's base-emitter voltage for basic self compensating circuit, the tempereature coefficients of base-emitter voltage of one transistor equal to the others for thermal compensation. By regarding the thermal and power drifts the experiments were performed were performed and the numerical results were consistent with the measured values.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.48-58
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• 1998

For the purpose of designing novel capacitance pressure sensor, several effects on sensitivity such as parasitic capacitance effects, temperature/thermal drift and leakage current have to be eleiminated. This paper proposed the experimental studies on frequency compensation method by electronic circuit technique, C-V converting method with switched capacitor and C-F converting method with schmitt trigger circuit. The third interface circuit by frequency compensation method is composed to eliminate the drift and leakage component by comparision sensing frequency with reference frequency. The signal transmission is realized by digital signal to minimize the influence of noise and high resolution is obtained by means of increasing the number of digital bits. In the fabricated high performance C-V interface, the offset voltage was not appeared, and in case of voltage source, 4.0V, feed back capacitance, 10㎊, the pressure, 0~10 ㎪, the sensitivity of C-V converter is 28 ㎷/㎪.V, the temperature drift characteristic, 0.051 %F.S./$^{\circ}C$ and C-F converter shows -6.6 Hz/pa, 0.078 %F.S./$^{\circ}C$ respectively, relatively good ones.