• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.465-468
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• 2001

An aerostatic stage has frictionless behavior, so it has a advantage of investigation into positioning characteristics. A one-dimensional aerostatic ceramic stage with ballscrew driven and laser scale feedback system is manufactured, aiming at investigating positioning characteristic of ultra-precision stage. We confirm, this ceramic aerostatic stage has a 10nm micro resolution, and can be reduced mean of position error by compensation of numeric control command. By means of analyzing relationship of position error and change of temperature, we build a on-line compensation algorithm of position error from the measured temperature data. So we can improve repeatability of ultra-precision stage up to 34%($0.095{\mu}$) of the normal condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.415-421
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• 2009

TOA(time-of-arrival) and TDOA(time-difference-of-arrival) positioning techniques are commonly used in many radio-navigation systems. From the literature, it is known that the position estimate and error covariance matrix of TDOA obtained by GN(Gauss-Newton) method is exactly the same as that of TOA when the error source of the range measurement is only an IID white Gaussian noise. In case of geo-location and indoor positioning, however, multi-path or NLOS(non-line-of-sight) error is frequently appeared in range measurements. Though its occurrence is random, the multipath acts like a bias for a stationary user if it occurs. This paper presents the comparisons of error characteristics between TOA and TDOA positioning in presence of multi-path or NLOS error. It is analytically shown that the position estimate of TDOA is exactly the same as that of TOA even when bias errors are included in range measurements with different magnitudes. By computer simulation, position estimation error and error distribution are analyzed in presence of range bias errors.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.9
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• pp.54-63
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• 1993

Quantization error, generated by the quantization process of an image, is inherent in computer vision. Because, especially in stereo vision, the quantization error in a 2-D image results in position errors in the reconstructed 3-D scene, it is necessary to analyze it mathematically. In this paper, the analysis of the probability density function (pdf) of quantization error for a line-based stereo matching scheme is presented. We show that the theoretical pdf of quantization error in the reconstructed 3-D position information has more general form than the conventional analysis for pixel-based stereo matching schemes. Computer simulation is observed to surpport the theoretical distribution.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.38-41
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• 1997

As the LPM is used for position accuracy decision device it is required that both the reason of posion error and the definition of position itself should be cleared. In this study, the precision of the position decision of LPM is affected by the geometrical shape such as tooth shape or processing accuracy. By using the analysis of magnetic circuit, we calculated the permeance come up with the gap. Once the thrust force has been obtained, the permeance due to the mechanical error of the pole pitch and the tooth pitch becomes the error of thrust force. We confirmed as well that it is being affected by the difference due to the variation of the airgap permeance.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1279-1286
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• 1999

In conventional GPS/DR integration schemes, the GPS position (or pseudo-range) information is used in calibrating DR sensors. In those schemes, however, an inaccurate calibration may degrade the position accuracy when the GPS measurement is not available. This paper presents a new integration scheme where the GPS velocity information is used in calibrating DR sensors. Also proposed is a new error model of DR sensors for calibrating the bias error and the tilt error in dynamic environments. The proposed model makes it possible that the errors of both the DR sensor parameters and the velocity are calibrated using the GPS carrier-based velocity(or the pseudo-range rate) measurement while the DR position error is calibrated using the GPS position measurement. Since the DR sensors are calibrated accurately, the positioning accuracy is drastically improved when the GPS measurements are unavailable.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.52-60
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• 2005

This paper deals with the position control fur a feed drive system in CNC milling machine, which utilizes a modified error signal for the elimination of steady-state error. A linear time-invariant (LTI) system has consistent properties in response to standard test signal inputs. Those also appear in an error curve acquired from the response. From such properties, constructed is an error model for the position control of the feed drive. And then added is the output of the error model to the current error signal. Consequently the resulting proportional control system brings performance improvement in view of the steady-state error. The effectiveness of the proposed scheme is confirmed through simulations and experiments.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.665-671
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• 1994

Some extended results in the study of two-position alignment for strapdown inertial navigation system are presented. In [1], an observability analysis for two-position alignment was done by analytic rank test of the stripped observability matrix and numerical calculation of the error covariance propagation using ten-state error model. In this paper, it is done by an analytic approach which utilizes the nonsingular condition of the determinant of simplified stripped observability matrix and by numerical calculation of the error covariance propagation accomplished in more cases than [1], and the twelve-state error model including vertical channel is used instead of ten-state error model. In addition, it is confirmed that this approach more clearly produces the same result as shown in the original work in terms of complete observability and there exist some better two-position configurations than [1] using the twelve-state error model.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.78-85
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• 2005

Initial alignment and localization are important topics in inertial navigation systems, since misalignment and initial position error wholly propagate into the navigation systems and deteriorate the performance of the systems. This paper presents the error convergence characteristics of the hybrid navigation system for underwater vehicles initial position, which is based on an inertial measurement unit (IMU) accompanying a range sensor. This paper demonstrates the improvement on the navigational performance oj the hybrid system with the range information, especially focused on the convergence of the estimation of underwater vehicles initial position error. Simulations are performed with experimental data obtained from a rotating ann test with a fish model. The convergence speed and condition of the initial error removal for random initial position errors are examined with Monte Carlo simulation. In addition, numerical simulation is conducted with an AUV model in lawn-mowing survey mode to illustrate the error convergence of the hybrid navigation System for initial position error.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.27-28
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• 2007

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.28 no.1
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• pp.39-51
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• 2022

Background: The purpose of this study is to investigate the effect of neck and shoulder self-stretching exercise using audiovisual media on neck pain, postural alignment, and joint position error in women with chronic neck pain. Methods: The subjects included 20 women that gave consent to participate in the study voluntarily. They performed the self-stretching exercises using audiovisual media was carried out 20 minutes 5 times a week during 3 weeks. Neck disability index (NDI) and visual analogue scale (VAS) were used to measure the functional disability and pain, A pressure pain threshold was measured using an algometer, and a cervical range of motion (CROM) measurement tool was used to measure the range of motion and error of proprioceptive position sense of the cervical spine. To assess posture alignment, forward head angle (FHA), forward shoulder angle (FSA) were measured using image J software. Results: The neck pain intensity was statistically significantly within group (p<.05). Neck and shoulder functional disability were a statistically significant difference within group (p<.05). Splenius capitis and upper trapezius pressure pain threshold were statistically significant difference in within group (p<.05). The postural alignment was statistically significantly within group (p<.05). The cervical range of motion in neck extension, right and left lateral flexion were statistically significantly within group (p<.05). The joint position error in neck flexion, extension, right and left lateral flexion decreased statistically significantly within group (p<.05). Conclusion: Self-stretching exercise using audiovisual media increased the mobility of the neck, decreased neck pain and joint position error, and improved posture alignment. As a result, there was a positive effect by applying the self-stretching exercise using audiovisual media to people with neck pain. Based on this, it is thought that it can be used as the basis for research related to home training programs for healthy self-management.