• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.48-53
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• 2010

5-axis CNC machining now is getting popular because it can deal with complex shapes such as impeller, turbine blade and propeller without additional equipment or process, proving a set of various tool orientations. CAM software related to 5-axis machining is being developed quickly so that users can take advantage of potential capacities of 5-axis machine tools. However, only a few researches can be found in the area of control strategy development for 5-axis machining. This paper proposes a 5-axis cross-coupling control system based on a novel tool orientation error model. The proposed tool orientation error model provides accurate information on the tool orientation error in real time, which in turn enables directly controlling the tool orientation accuracy. The proposed control system also employs a contour error model to calculate the contour error and reflect it in the control as well. The accuracy of the proposed tool orientation error model is verified and the performance of the 5-axis cross-coupling control system in terms of both contouring and tool orientation accuracy is evaluated through computer simulations compared with existing 5-axis control systems.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.122-129
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• 1999

A 5-axis CNC machine tool is more useful compared with a 3-axis machine tool, because the position and the orientation of a tool tip can be controlled simultaneously. Unlike the 3-axis machine tool, the 5-axis machine tool has the volumetric position error and volumetric orientation error due to the quasi-static error of each machine tool joint which is a major source of machined part error. So, the generalized error synthesis model of the 5-axis CNC machine tool was developed to predict and to compensate for the volumetric position error and the volumetric orientation error. It was proposed that a compensation algorithm to correct simultaneously the volumetric position error and the volumetric orientation error of the 5-axis CNC machine by error inverse kinematic.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.672-675
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• 2000

There are many sources of errors in the parallel device. This study investigates the effect of a clearance error at a U-joint on the position and orientation errors of the platform of a new parallel device, cubic parallel manipulator. In this study, the limits of errors can be estimated for given conditions.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.11
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• pp.63-72
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• 1997

The design and implementation of a drive wheel position, orientation, and velocity feedback control algorithm for a differential-drive mobile robot is described here. A new concept, the most significant error, is introduced as the control design objective. Drive wheel position, orientation, and velocity feedback control directly minimize the most siginificant error by coordinating the motion of the two drive wheels. The drive wheel position, orientation, and velocity feedback control algorithm is analyzed and experiments are conducted to evaluate its performance. The experimental results are shown that drive wheel position, orientation and velocity feedback control algorithm yields substantially smaller position and orientation errors than those of conventional methods.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.532-535
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• 1997

This paper describes the design of a fuzzy-logic controller for a differential-drive mobile robots. This controller uses absolute position information to modify control parameters to compensate the orientation error. CC-Control method is compensated for the internal error by wheel encoders and the fuzzy-logic control provides compensation for external errors. The validities of the proposed scheme is evaluated using simulation.

• Journal of the Ergonomics Society of Korea
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• v.9 no.1
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• pp.35-42
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• 1990

This study is concerned with the accuracy, of error with which subjects can interpolate the location of a target between two graduation markers with 4 orientations and 6 sizes CRT display. Stimuli were graphic images on CRT with a linear, end-markec, ungraduated scales having a target. The location of a target is estimated in units over te range 1-99. Smallest error of estimates was at the near ends and middle of the base-line. The median error was less than 2 units, modal error was 1, and the most error (; 99.7%) was within 10. A proper size to make an minimum error in interpolation exists such that size 400 pixels. Interpolation estimation is shown to be affected by the size, location and interaction (orientation x location, size x location). The accuracy, interpolation performance are discussed in relation to absolute error associated with visual performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.211-214
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• 2000

An error analysis is very important for a precision machine tool to estimate its performance. This study proposes a new parallel device, a cubic parallel manipulator. Errors of the proposed cubic parallel manipulator include universal joint errors, errors occurring due to changes in the fore directions in the links, and actuation errors. An error analysis is performed for the manipulator platform moving at uniform velocity. The analysis shows how the position and orientation of the platform influences the directional link forces that change the errors in the manipulator. The analysis shows that the method can be used in predicting the accuracy of parallel devices.

• Journal of Korea Multimedia Society
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• v.6 no.4
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• pp.698-706
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• 2003

The primary goal of surface approximation is to reduce the degree of deviation of the simplified surface from the original surface. However it is difficult to define the metric that can measure the amount of deviation quantitatively. Many of the existing studies analogize it by using the change of the scalar quantity before and after simplification. This approach makes a lot of sense in the point that the local surfaces with small scalar are relatively less important since they make a low impact on the adjacent areas and thus can be removed from the current surface. However using scalar value alone there can exist many cases that cannot compute the degree of geometric importance of local surface. Especially the perceptual geometric features providing important clues to understand an object, in our observation, are generally constructed with small scalar value. This means that the distinguishing features can be removed in the earlier stage of the simplification process. In this paper, to resolve this problem, we present various factors and their combination as the metric for calculating the deviation error by introducing the orientation of local surfaces. Experimental results indicate that the surface orientation has an important influence on measuring deviation error and the proposed combined error metric works well retaining the relatively high curvature regions on the object's surface constructed with various and complex curvatures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.479-482
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• 2001

An error analysis is very important for a precision machine to estimate its performances. This study proposes a new parallel device. cubic parallel manipulator. There are so many error sources in this mechanism. Errors of the proposed cubic parallel vary with the stiffness of the manipulator. The stiffness of each leg depends on the direction of the actuation force and its direction. In this paper, the stiffness of the manipulator is calculated and the position errors and the orientation errors are predicted with the platform moving. The analysis shows that the method can be used in predicting the accuracy of other parallel devices and in designing a parallel manipulator.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.24-29
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• 2002

In any rapid prototyping process, the layer by layer building process introduces an area error between the staircase and the surface line specified by the computer-aided design model. This affects the dimensional accuracy as well as the surface finish for different part build orientations. This paper describes a methodology for computing the area error for any orientation of the part built by the fused deposition modelling system. This technique can be applied to determine the best build orientation of the part, based on the minimum area error. This technique is verified by comparing the results with the experimental measurements of the area error of the parts built at different orientations.