• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.524-529
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• 2004

Recently High precision positioning device is used in many kinds of manufacturing and scientific instruments. Piezoelectric transducer is applied to the positioning devive as actuator, PZT has a high resolution, however, moving range is short. Many researcher have developed the mechanism for increasing a motion range. The types of increasing motion range mechanism with PZT are inertial slider, friction driver, ultrasonic motor, etc. In this paper we discuss the review of the hish precision actuator mechanism with PZT. Many kinds of mechanism for high precision are shown and compared.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1394-1397
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• 2005

The object of this study was to design of micro stage, which is one of the equipments embodied in ultra precision positioning mechanism. Design factors for micro stage were decided a roundness of hinge, a thickness of hinge, a thickness of stage, a length of arms and a clearance of division. To obtain the $1^{st}$ natural frequency and equivalent stresses, FEM simulation was performed using the table of orthogonal arrays and Taguchi method was used to determine the optimal design parameters. As results of this study, the size of 1st natural frequency and equivalent stresses on micro stage was influenced significantly by a thickness of hinge and a length of arm.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.204-209
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• 2003

Cam mechanisms are one of the most popular devices for generating intermittent motion and are widely used in many areas. Also, as being interested in research of precision field, cam mechanism is required high accuracy and continuity, In. In this paper, the cam mechanism of filament automatic assembly machine design for precision motion is proposed. The modelling of a cam mechanism, cam profile functions, and the design of the cam considering the precision positioning of the cam mechanism is studied. And, simulation of designed cam mechanism had been carried out dynamic analysis.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.37.3-37
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• 2001

The quality of a precision product, in genera, relies on the accuracy and precision of its manufacturing and inspection process. In many cases, the level of precision in the manufacturing and inspection system is also dependent on the positioning capability of tool with respect to the workpiece in the process. Recently the positioning accuracy level employed for some of precision product has reached the level of submicron and long range of motion is required. For example, for 1GDRM lithography, 20nm accuracy and 300nm stroke needs. This paper refers to the lithography stage especially fine stage. In this study, for long stroke and high accuracy, the dual servo system is proposed. For the coarse actuator, LDM(Linear DC Noter) is used and for fine or VCM is used ...

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.1
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• pp.32-37
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• 2008

This paper presents a new precision stage by using the PZT actuator and stepping motor. The stage have the precision positioning mechanism that has been developed for generation displacements with nanometer accuracy and a millimeter dynamic range simulatneously. The stage is composed not of the mechanical elastic hinge but of the clamp, and only one PZT actuator. The displacement of stage is acquired by the control of the two clamp between the PZT actuator. The results of the FEM analysis in the contact part of the clamp and basic properties of the positioning system are also presented. Using the new stage proposed in this paper.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.12
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• pp.1366-1371
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• 2011

In ultra precision machining, it is necessary to adjust the horizontality and reference position of a workpiece in a noncontact manner. For this, a simple process by measuring impedance between a tool tip and a workpiece which are connected to impedance analyzer is proposed. As the distance between the tool and the workpiece gets closer, the reduction rate of impedance becomes higher over all frequency ranges. By setting threshold value of impedance reduction rate at specific frequencies through preliminary experiments, the distance between the tool and the workpiece can be predicted and it directly enables us to horizontalize the workpiece and to set the tool to the desired reference position.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.52-59
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• 2001

In this paper, we have proposed a capability of applying Global Positioning System(GPS) to cannon laying. High precision GPS positioning can be used for measuring precise positions and angles. Therefore, we have tested on applying GPS positioning technique to measurement of positions and angles, which related to cannon laying. First of all, we have determined a GPS reference position using various positioning methods. Then we have carried out several tests that are process of taking corner angles between neighboring two vectors. Each vector can be calculated by post/real time positioning of two GPS antennas placed on the both ends of the howitzer. The Comer Angles from Post processing(CAP) are compared with the other Corner Angles from Real time positioning(CAR). As the results, we have an agreement between CAP and CAR within 0.25 mil average, 0.29 mil standard deviation. Finally, we have discussed about the capabilities and problems in artillery arrangement using GPS.

• Proceedings of the KSRS Conference
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• v.2
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• pp.756-759
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• 2006

The ocean tide loading (OTL) is an important factor for the GPS positioning, especially in the height direction. The shorter of the distance to the ocean, the larger of the error by the OTL. The influence will be changed when we measure in different place and the order of magnitude is from few centimeters to ten centimeters. In this study, more than ten kinds of the OTL models were collected and applied on the GPS static relative positioning in Taiwan. The GPS observations including five stations were obtained from Nov. 9, 2004 to Feb. 23, 2005 and we used the Bernese GPS software to execute the data processing. In this period, the average amplitudes of the 3-D coordinates are as follows: N is 0.4 cm, E is 0.7 cm, h is 1.8 cm at Kinmen station; N is 0.7 cm, E is 1.3 cm, h is 2.3 cm at Lanyu station; N is 0.5 cm, E is 0.7 cm, h is 2.0 cm at Matsu station; N is 0.6 cm, E is 0.6 cm, h is 2.0 cm at Penghu station and N is 0.5 cm, E is 1.2 cm, h is 1.7 cm at Hsinchu station. Moreover, we will analyze the advantage and disadvantage of every kind of the OTL models in different environments to offer some information to the GPS users and enhance the precision of the GPS positioning.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.277-280
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• 2008

Enhancing the positioning precision is the primary pursuit of GPS users. To achieve this goal, most studies have focused on the relationship between GPS receiver clock errors and GPS positioning precision. This study utilizes undifferentiated phase data to calculate GPS clock errors and to compare with the frequency of cesium clock directly, thus verifying estimated clock errors by the method used in this paper. The relative frequency offsets from this paper and from National Standard Time and Frequency Laboratory of Taiwan match to $1.5{\times}10^{12}$ in the frequency instability, suggesting that the proposed technique has reached a certain level of quality. The built-in quartz clocks in the GPS receivers yield relative frequency offsets that are 3 to 4 orders higher than those of rubidium clocks. The frequency instability of the quartz clocks is on average two orders worse than that of the rubidium clock. Using the rubidium clock instead of the quartz clock, the horizontal and vertical positioning accuracies were improved by 26-78% (0.6-3.6 mm) and 20-34% (1.3-3.0 mm), respectively, for a short baseline. These improvements are 7-25% (0.3-1.7 mm) and 11% (1.7 mm) for a long baseline. Our experiments show that the frequency instability of clock, rather than relative frequency offset, is the governing factor of positioning accuracy.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.90-94
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• 2007

The conventional single-reference station positioning is affected by systematic errors such as ionospheric and tropospheric delay, so that the rover must be located within 10 km from the reference station in order to acquire centimeter-level accuracy. The medium-range real-time kinematic has been proven feasible and can be used for high precision applications. However, the longer of the baseline, the more of the time for resolving the integral ambiguity is required. This is due to the fact that systematic errors can not be eliminated effectively by double-differencing. Recently, network approaches have been proposed to overcome the limitation of the single-reference station positioning. The real-time systematic error modeling can be achieved with the use of GPS network. For expanding the effective range and decreasing the density of the reference stations, Land Survey Bureau, Ministry of the Interior in Taiwan set up a national GPS network. In order to obtain the high precision positioning and provide the multi-goals services, a GPS network including 66 stations already been constructed in Taiwan. The users can download the corrections from the data center via the wireless internet and obtain the centimeter-level accuracy positioning. The service is very useful for surveyors and the high precision coordinates can be obtained real time.