• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.10 no.4
• /
• pp.97-103
• /
• 2001

The study on the high-speed machine tool is very important for the improvement of productivity since it can shortens cutting and non-cutting time. Especially, high speed of feed drive system is the major research field. In the industries of the advanced countries, the feed drive systems at the speed of 60 m/min have been already developed based on the high lead ball screws. In this study, a high speed feed drive system at the speed of 60 m/ min has been developed, and its movements characteris-tics are investigated. As the movement characteristics, positioning accuracy, angular accuracy, straightness and micro step-response are measured. Thermal characteristics of the system is also discussed. For measuring the movement characteris-tics, a laser interferometer, a memory-based Hi-coder and a cooling device are used. The experimental results confirm that the movement characteristics and the thermal behavior of the system are satisfactory in the aspect of accuracy and stability.

• Journal of Magnetics
• /
• v.22 no.1
• /
• pp.150-154
• /
• 2017

A novel high precision spatial positioning method utilizing the electromagnetic momentum, i.e., Electromagnetic Momentum Positioning (EMP), is proposed in this paper. By measuring the momentum of the electromagnetic field around the small current loop, the relative position between the sensor and the current loop is calculated. This method is particularly suitable for the application of close-range and high-precision positioning, e.g., data gloves and medical devices in personal healthcare, etc. The simulation results show that EMP method can give a high accuracy with the positioning error less than 1 mm, which is better than the traditional magnetic positioning devices with the error greater than 1 cm. This method lays the foundation for the application of data gloves to meet the accurate positioning requirement, such as the high precision interaction in Virtual Reality (VR), Augmented Reality (AR) and personal wearable devices network.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.467-467
• /
• 2000

In this paper, a structural design method of robust motion controllers for high-accuracy positioning systems, which makes it possible to predict the performance of the whole closed-loop system, is proposed. First, a stabilizing control input is designed based on robust internal-loop compensate.(RTC) for the system in the presence of uncertainty and disturbance. Next, using the structural characteristics of the RIC, disturbance attenuation properties and the performance of the closed-loop system determined by the variation of controller gains are analyzed. Through this analysis, in some specific applications, it is shown that if the control gain of RIC is increased by N times, the magnitude of error is reduced to its 1/N. Finally, the proposed method is verified through experiments using a high-accuracy positioning system used in the semiconductor chip mounting devices.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.118-122
• /
• 2000

Recently, High accuracy and precision are required in various industrial field especially, semiconductor manufacturing apparatus, Ultra precision positioning apparatus, Information field and so on. Positioning technology is a very important one among them. For composition of this technology, the development of system with high speed and high resolution is needed. At start point and end position vibration must be repressed on this system for composition of position control. This vibration is arisen nose, is increased setting time, is reduced accuracy. Especially, repressed for the lead with high speed. The small actuator with high speed and high resolution is need to repression against this residual vibration. This actuator is, for example, piezo actuator, piezoelectric material that converting from electronic signal to mechanical force is adequate material, beacause of control of control to position and force. In this study, piezo electric material is used to actuator, ultra precision positioning apparatus with stage of hinge structure is designed, simulation is performed, control performance is tested by producing apparatus. For easy usage and stability in industrial field, we perform to simulation and to position control test by digital PID controller.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.12
• /
• pp.1950-1958
• /
• 2016

Today, technique for precisely positioning vehicles is very important in C-ITS(Cooperative Intelligent Transport System), Self-Driving Car and other information technology relating to transportation. Though the most popular technology for vehicle positioning is the GPS, its accuracy is not reliable because of large delay caused by multipath effect, which is very bad for realtime traffic application. Therefore, in this paper, we proposed the Vision-Based High Accuracy Vehicle Positioning Technology. At the first step of proposed algorithm, the ROI is set up for road area and the vehicles detection. Then, center and four corners points of found vehicles on the road are determined. Lastly, these points are converted into aerial view map using homography matrix. By analyzing performance of algorithm, we find out that this technique has high accuracy with average error of result is less than about 20cm and the maximum value is not exceed 44.72cm. In addition, it is confirmed that the process of this algorithm is fast enough for real-time positioning at the $22-25_{FPS}$.

• ETRI Journal
• /
• v.30 no.1
• /
• pp.59-67
• /
• 2008

The necessity for the precise time synchronization of measurement data from multiple sensors is widely recognized in the field of global positioning system/inertial navigation system (GPS/INS) integration. Having precise time synchronization is critical for achieving high data fusion performance. The limitations and advantages of various time synchronization scenarios and existing solutions are investigated in this paper. A criterion for evaluating synchronization accuracy requirements is derived on the basis of a comparison of the Kalman filter innovation series and the platform dynamics. An innovative time synchronization solution using a counter and two latching registers is proposed. The proposed solution has been implemented with off-the-shelf components and tested. The resolution and accuracy analysis shows that the proposed solution can achieve a time synchronization accuracy of 0.1 ms if INS can provide a hard-wired timing signal. A synchronization accuracy of 2 ms was achieved when the test system was used to synchronize a low-grade micro-electromechanical inertial measurement unit (IMU), which has only an RS-232 data output interface.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.5 s.236
• /
• pp.770-776
• /
• 2005

The gains fur NC controller parameter are fixed when the controller is combined with a machine. However, the characteristics of controller could be changed as it has being used by the machine or other environmental conditions. Those result in that the tool positioning accuracy is influenced. The loading torque in servo motor influences on the tool positioning accuracy and it is controlled by the parameter gains. It is required to analyze the torque variation with angular positioning accuracy of the servo motor. This study focus on a measuring method and device for verifying angular positioning accuracy of NC servo motor. We used a high resolution An converter for acquiring analogue signal of rotary encoder in servo motor. The positional accuracy for a nominal tool path, which is generated by the combination of axial movements (X,Y,Z), is analyzed with the servo motor torque. The current variation signal is acquired at the power line using a hall sensor and converted to the loading torque of servo motor. The method of measurement and analysis proposed in this study will be used for determining the gains of parameter in NC controller. This gain tuning is also necessary when the controller is set up at a machine.

• Journal of Positioning, Navigation, and Timing
• /
• v.6 no.2
• /
• pp.53-57
• /
• 2017

eLoran refers to a terrestrial navigation system using high-power low-frequency signals. Thus, it can be regarded as a positioning, navigation and timing (PNT) system to back up a global navigation satellite system (GNSS) or an alternative to GNSS. South Korea is vulnerable to interference such as GNSS jamming in particular. Therefore, South Korea has made an effort to develop an independent navigation system through eLoran system. More particularly, an eLoran testbed has been developed to be used in the northwest sea area and research on applicability of eLoran in South Korea has been underway. The present study analyzes expected performance of eLoran according to locations of newly built eLoran transmitting stations as part of the eLoran testbed research. The performance of eLoran is analyzed in terms of horizontal position accuracy, and horizontal dilution of precision (HDOP) information was used since it affects accuracy significantly. The target service areas of the eLoran testbed are Incheon and Pyeongtaek Ports, and the required target performance is positioning accuracy of 20 m position within 30 km coverage of the target service area.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.10
• /
• pp.2679-2691
• /
• 2012

In this paper, a high accuracy stereo reconstruction method for surgery instruments positioning is proposed. Usually, the problem of surgical instruments reconstruction is considered as a basic task in computer vision to estimate the 3-D position of each marker on a surgery instrument from three pairs of image points. However, the existing methods considered the 3-D reconstruction of the points separately thus ignore the structure information. Meanwhile, the errors from light variation, imaging noise and quantization still affect the reconstruction accuracy. This paper proposes a method which takes the structure information of surgical instruments as constraints, and reconstructs the whole markers on one surgical instrument together. Firstly, we calibrate the instruments before navigation to get the structure parameters. The structure parameters consist of markers' number, distances between each markers and a linearity sign of each instrument. Then, the structure constraints are added to stereo reconstruction. Finally, weighted filter is used to reduce the jitter. Experiments conducted on surgery navigation system showed that our method not only improve accuracy effectively but also reduce the jitter of surgical instrument greatly.

• Proceedings of the KSRS Conference
• /
• 2007.10a
• /
• pp.564-567
• /
• 2007

GPS(Global Positioning System) data has a high accuracy at outdoor positioning generally, but its accuracy decreases in the urban areas with dense buildings. Moreover insufficient number of satelllites prevent us GPS positioning at inside of buildings. To complement these shortcomings of GPS, RFID(Radio Frequency IDentification) has been studied on indoor positioning parts. In Ubiquitous environment, LBS(Location Based Service) which can be used anytime and anywhere is an essential component. We use kalman filter to estimate the real location in GPS and RFID handover area. This study's purpose is to make a continuous positioning system using interlocking RFID and GPS.