• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.190-194
• /
• 2001

Because, Piezo-electric transducer(PZT) transform electric energy into mechanical energy, it is a adequate material for positioning control and force control, take excellent properties as actuator with high speed and high performance. Recently, researches of ultra precision positioning using this PZT are advanced in. In this paper, we use a actuator of PZT, design a positioning apparatus with ultra precision position apparatus as hinge structure. Because of this purpose, before, we were confirmed in control properties of ultra precision stage by FEM method.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.22 no.4
• /
• pp.386-392
• /
• 2002

Ultrasonic has been proposed as an attractive means of detecting bone loss. There have been several commercial ultrasound devices developed for measuring the heel to predict fracture at other bones. However, these devices select only single point of heel bone as measurement site. It causes poor assessment of bone quality due to the error of transducer positioning. In an effort to improve current ultrasound systems, we evaluated the linear scanning method which provides better prediction of bone quality and an accurate image of bone shape. The system used in this study biaxially scans a heel bone using automated linear scanning technique. The results demonstrated that the values of ultrasound parameters varied with different positions within bone specimen. It has been also found that the linear scanning method could better pre야ct bone quality, eliminating the error of transducer positioning.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.378-378
• /
• 2000

The permissible positioning error of the transducer used in reactor inspection must be within 10 mm. To implement the required precision it is necessary to manufacture all components affecting the positioning mechanism correctly and precisely. In addition, it is also necessary to handle error factors accurately. This paper describes the activities of the findings and corrections of the errors which were occurred in experiments. Those activities are; i) Categorization of error factors, ii) Cause analysis of errors, iii) Correction of errors founded in experiments by the analysis of laser induction type and by the validation of real measurement of horizontal, vertical baselines.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.175-180
• /
• 2003

Ultrasonic pulse velocity method is applied many times for measuring surface crack depth of concrete in case of diagnosis of concrete structures. By the way, this method has an error accompanying measured surface crack depth of concrete because there are many uncertainty factors. So, it is necessary to study for an error of this method affected by these uncertainty factors. Two error factors(uncertainty factors) are tested and analyzed in this study. One is for an error according to measuring the propagation time of ultrasonic wave and the arrangement distance of transducers. Another is for an error according to positioning the transducer as a distance to surface crack from the transducer.

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

• Journal of the Korean Society for Precision Engineering
• /
• v.9 no.4
• /
• pp.13-21
• /
• 1992

Standards concerning the determination of positioning accuracy and repeatability of numerically controlled(NC) machine tools have been published relentlessly over the last 20 years. Since the publication in 1988 of the International Standard 230-2 there has been a pronounced move, both at national and international standards level, to embrace further test procedures for a complete machine tool performance assessment. For example, measurements of angular (pitch, roll, and yaw) and straightness errors along linear axes are now commonplace and complement the existing positioning accuracy and repeatablity tests. More recently the subject of circularity evalutaion has also gained considerable interest. Here dynamic tests, using a kinematic ballbar or circular masterpiece, give an instant overview of the contouring ability of the machine in two axes at specific feedrates. This information is extremely important in optimising machining accuracy. This paper describes moves to complete the machine calibration package in national and international standardis- ation for the assessment of machine tool performance.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1994.10a
• /
• pp.254-259
• /
• 1994

Recently, the precision ball screw becomes the essence of the high-precision industries and is playing a key role in the positioning devices. The standard and definition of pitch error in a precision ball screw is specified by KS, JIS or ISO. However, the method of measuring the pitch error is not concrete. In this study. laser measurement system(LMS) with a laser position transducer and a machine-tools is developed. In order to verify the stability of the LMS, several experiments with the standard ball screw is performed.

• Journal of Ocean Engineering and Technology
• /
• v.33 no.5
• /
• pp.470-478
• /
• 2019

Because the global positioning system (GPS) is not available in underwater environments, an inertial navigation system (INS)/doppler velocity log (DVL) integrated navigation system is generally implemented. In general, an INS/DVL integrated system adopts a loosely coupled method. However, in this loosely coupled method, although the measurement equation for the filter design is simple, the velocity of the body frame cannot be accurately measured if even one of the DVL transducer signals is not received. In contrast, even if only one or two velocities are measured by the DVL transducers, the tightly coupled method can utilize them as measurements and suppress the error increase of the INS. In this paper, a filter was designed to regenerate the measurements of failed transducers by taking advantage of the tightly coupled method. The regenerated measurements were the normal DVL transducer measurements and the estimated velocity in RPM. In order to effectively estimate the velocity in RPM, a filter was designed considering the effects of the tide. The proposed filter does not switch all of the measurements to RPM if the DVL transducer fails, but only switches information from the failed transducer. In this case, the filter has the advantage of being able to be used as a measurement while continuously estimating the RPM error state. A Monte Carlo simulation was used to determine the performance of the proposed filters, and the scope of the analysis was shown by the standard deviation ($1{\sigma}$, 68%). Finally, the performance of the proposed filter was verified by comparison with the conventional tightly coupled method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.11
• /
• pp.1613-1622
• /
• 2010

In this paper, the ultraprecision positioning control of an ultrasonic linear motor in a high-vacuum environment is presented. The bolt-clamped Langivin type transducer (BLT) with the 3rd longitudinal; and 6th lateral vibration modes was developed, which was excited by using the Eigen resonance frequency for two vibration modes in order to generate stable and high power. In practical applications, however, even if a geometrical design has an Eigen frequency, discordance between both mode frequencies can be generated by the contact mechanism and because of manufacturing errors as well as environmental factors. Both mode frequencies were precisely matched by adjusting the impedence. By using this method, the BLT can be driven under any environmental conditions. The nominal characteristic trajectory following(NCTF) control method was adopted to control the positioning of the system in vacuum. The developed linear motor stage show high positioning accuracy with 5 nm.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.151-152
• /
• 2006

Nowadays, great attention has been shown to the question of ultrasonic linear motor for accomplishing the high positioning accuracy and high driving force in the semiconductor and optical industry. Ultrasonic linear motors have many advantages such as simple structure, quick response, ability to maintain position without energy consumption, and electromagnetic effect. And BLT has attracted attention to accomplish large vibration amplitude and large mechanical force. Authors designed and developed the new type of ultra sonic linear motor with multi support mechanism, achieved 75N of output force and 0.45m/s of velocity.