• 한국기계가공학회지
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• 제9권3호
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• pp.1-7
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• 2010

The aim of this research is to evaluate movement and path characteristics of developed heavy duty handling robot using laser tracker(API T3) according to the ISO 9283 robot performance evaluation criteria. As carry out 3D modeling and simulation using CATIA, a test cube was set up to select moving and measuring range of robot. Performance test for pose and distance accuracy, path and path velocity accuracy under payload zero and 440kgf was accomplished. The resulted output data show the reliability of the developed robot.

• 수산해양기술연구
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• 제21권2호
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• pp.123-130
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• 1985

Loran-C 위치의 정도를 높이기 위하여 제주지역을 대상으로 북동태평양 Chain (GRI 5970)에 대한 시간차를 관측하여 그 전파경로와 측지계 및 전파속도에 따른 시간차오차 등을 분석 검토한 결과는 다음과 같다. 1. Loran-C 전파는 M-X 조국, M-Y조국 모두 주국, X, Y 종국과 관측점 사이에 높이 500m 이상 되는 한라산을 통과하여 전파될 때 시간차 오차가 커짐을 알 수 있었다. 2. 측지계 및 전파속도의 보정에 따른 시간차오차는 M-X 조국에서는 측지계변환과 속도보정을 행할수록 적어지고, M-Y조국에서는 M-X조국과는 달리 해상 및 육상의 전파경로에 따라 시간차오차가 불규칙적으로 변함을 알 수 있었다. 3. 보정요소별 측위의 정도는 측지계를 변화하고 속도보정을 행한 것이 가장 높고, WGS-72 측지계를 변환시키지 않은 것이 가장 낮았다. 4. 측정위치의 정도를 향상시키기 위해서는 굴절율에 의한 속도보정과 측지계변환 및 육상전파속도보정을 행하여야 함을 알 수 있었다.

• International Journal of Control, Automation, and Systems
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• 제6권3호
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• pp.386-393
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• 2008

A position control method for interpolating aspherical grinding and polishing tool path was reviewed and experimented in a nano precision machine. The position-base algorithm was reformed from the time-base algorithm, proposed in the previous study. The characteristics of the algorithm were in the velocity control loop with position feedback. The aspherical surface was divided by an interval at which each velocity and acceleration were calculated. The theoretical velocity was corrected by position error during processing. In the experiment, a machine was constructed and nano-scale linear encoders were installed at each axis. Relation between process parameters and the variation of position error was monitored and discussed. The best result from optimized parameters showed that the accuracy was 150nm and improved from the previous report.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.100-103
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• 2005

In this study, tool path control algorithm for aspherical surface grinding was derived and discussed. The aspherical surface actually means contact points between lens and tool. Tool positions are generally defined at the center of a tool, so there is difference between tool path and lens surface. The path was obtained from contact angle and relative position from the contact point. The angle could be calculated after differentiating an aspheric equation and complex algebraic operations. The assumption of the control algorithm was that x moves by constant velocity while z velocity varies. X was normal to the radial direction of lens, but z was tangential. The z velocities and accelerations were determined from current error and next position in each step. In the experiment, accuracy of the control algorithm was checked on a micro-precision machine. The result showed that the control error tended to be diminished when the tool diameter increased, and the error was under sub-micro level.

• 한국유체기계학회 논문집
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• 제7권5호
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• pp.7-12
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• 2004

Multi-path ultrasonic flowrate measuring technology is being received much attentions from a variety of industrial fields to exactly measure the flowrate. Multi-path ultrasonic flowmeter has much advantage since it has no moving parts and little pressure loss. It offers good accuracy, repeatability, linearity and turn-down ratio can be over 1:50. The present study investigates flowrate integration errors using weighting factors. A theoretical flow model uses power law to describe a fully developed velocity profiles and wall roughness is changed. Gaussian, Chebyshev, and Tailor methods are used to integrate line-average velocities. The obtained results show that Chebyshev method in 2, 4-path arrangement and Gaussian method in 3, 5-path arrangement are not affected for wall roughness changes.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.154-160
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• 2003

Multi-path ultrasonic flowrate measuring technology is being received much attentions from a variety of industrial fields to exactly measure the flowmeter. Multi-path ultrasonic flowmeter has much advantage since it has no moving parts and not occurred pressure loss. It offers good accuracy, repeatability, linearity and Tum-down ratio can measure over 1:50. The present study investigates flowrate integration errors using weighting factors. A theoretical flow model uses power law to describe a fully developed velocity profiles and wall roughness changes. The methods of weighting factor simulate three configurations of measuring location of gaussian, chebyshev and tailor method. The obtained results show that many chord arrangements are not affected for wall roughness changes and can measure accurate flowrate.

• 전기전자학회논문지
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• 제26권2호
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• pp.150-159
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• 2022

본 논문에서는 증강현실(AR) 당구 콘텐츠를 위한 물리 시뮬레이션을 제안한다. 제안하는 증강현실 당구 콘텐츠에 대한 물리 시뮬레이션의 특징은 다음과 같다. 먼저, 증강현실 환경에서 실제와 비슷한 당구공의 움직임을 구현하기 위해 당구공에 적용되는 힘과 관성모멘트 계산을 하여 물리식을 도출한다. 다음에 타격 지점에 대한 가상 당구공의 회전과 관련된 가상 당구공의 속도와 각속도를 구한다. 다음으로, 가상 당구공의 움직임 궤적이 실제 당구공과 비슷한 움직임을 구현하기 위하여 입사벡터, 법선벡터, 반사벡터 등의 물리식을 도출하게 된다. 이러한 방정식을 증강현실 환경에 적용하여 AR 당구 콘텐츠를 구현할 수 있다. 이러한 물리 시뮬레이션은 사용자가 가상 당구대를 사용하여 실제와 유사함을 느낄 수 있도록 하며 실제 환경과 상호 작용하게 돕는다. 실험 결과 실제 당구공의 경로와 가상 당구공의 경로 사이의 정확도 범위는 97.75%~99.11%로 계산됐다. 따라서 본 논문에서 제안하는 증강현실 당구 콘텐츠에 대한 물리 시뮬레이션의 성능은 실제 당구공의 경로와 유사함을 확인하였다.

• 드라이브 ㆍ 컨트롤
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• 제17권1호
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• pp.13-20
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• 2020

Adaptive neural networks based lateral controller is presented to guarantee path following performance for vehicle lane keeping in the presence of parameter time-varying characteristics of the vehicle lateral dynamics due to the road surface condition, load distribution, tire pressure and so on. The proposed adaptive controller could compensate vehicle lateral dynamics deviated from nominal dynamics resulting from parameter variations by incorporating it with neural networks that have the ability to approximate any given nonlinear function by adjusting weighting matrices. The controller is derived by using Lyapunov-based approach, which provides adaptive update rules for weighting matrices of neural networks. To show the superiority of the presented adaptive neural networks controller, the simulation results are given while comparing with backstepping controller chosen as the baseline controller. According to the simulation results, it is shown that the proposed controller can effectively keep the vehicle tracking the pre-given trajectory in high velocity and curvature with much accuracy under parameter variations.

• 자동차안전학회지
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• 제13권4호
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• pp.123-128
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• 2021

This paper present box feature estimation from LiDAR point cluster using maximum likelihood Method. Previous LiDAR tracking method for autonomous driving shows high accuracy about velocity and heading of point cluster. However, Assuming the average position of a point cluster as the vehicle position has a lower accuracy than ground truth. Therefore, the box feature estimation algorithm to improve position accuracy of autonomous driving perception consists of two procedures. Firstly, proposed algorithm calculates vehicle candidate position based on relative position of point cluster. Secondly, to reflect the features of the point cluster in estimation, the likelihood of the particle scattered around the candidate position is used. The proposed estimation method has been implemented in robot operating system (ROS) environment, and investigated via simulation and actual vehicle test. The test result show that proposed cluster position estimation enhances perception and path planning performance in autonomous driving.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.57-58
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• 2006

A Simulation model is developed to minimize the path tracking errors when the non-circular cutting is done by a VCM(voice coil motor) driven tool. The relationship between PWM(Pulse Width Modulation) duty ratio and velocity of voice coil motor is theoretically derived from combining the circuit equation for the coils and the motion equation for the magnetic rod of the voice coil motor. The path tracking errors are showed differently according to the rotational speed, the number of segments and the control period in digital control. Given a required accuracy in the non-circular cutting, the optimal values for those parameters are determined based on the developed simulation model.