• Proceedings of the KSRS Conference
• /
• v.2
• /
• pp.684-687
• /
• 2006

Airborne imagery must be precisely orthorectified to be used as geographical information data. GPS/INS (Global Positioning System/Inertial Navigation System) and LIDAR (LIght Detection And Ranging) data were employed to automatically orthorectify airborne images. In this study, 154 frame airborne images and LIDAR vector data were acquired. LIDAR vector data were converted to raster image for employing as reference data. To derive images with constant brightness, flat field correction was applied to the whole images. The airborne images were geometrically corrected by calculating internal orientation and external orientation using GPS/INS data and then orthorectified using LIDAR digital elevation model image. The precision of orthorectified images was validated using 50 ground control points collected in arbitrary selected five images and LIDAR intensity image. In validation results, RMSE (Root Mean Square Error) was 0.365 smaller then two times of pixel spatial resolution at the surface. It is possible that the derived mosaicked airborne image by this automatic orthorectification method is employed as geographical information data.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.1
• /
• pp.73-78
• /
• 2007

The process and results of Captive Flight Test(CFT), conducted by Agency for Defense Development(ADD) using the Korean KTX-1 trainer and external fuel tank, are presented. Through over 150 sorties of CFT, the guided weapon system's critical subsystems like Seeker, Navigation Device and Technology, Inertial Sensor, and Radio Altimeter are tested and evaluated. Using the CFT, time and cost are saved in weapon system research and development procedure.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.2
• /
• pp.169-176
• /
• 2012

GPS(Global Positioning System) is widely used for the position estimation of an aerial vehicle. However, GPS may not be available due to hostile jamming or strategic reasons. A vision-based position estimation method can be effective if GPS does not work properly. In mountainous areas without any man-made landmark, a horizon is a good feature for estimating the position of an aerial vehicle. In this paper, we present a new method to estimate the position of the aerial vehicle equipped with a forward-looking infrared camera. It is assumed that INS(Inertial Navigation System) provides the attitudes of an aerial vehicle and a camera. The horizon extracted from an infrared image is compared with horizon models generated from DEM(Digital Elevation Map). Because of a narrow field of view of the camera, two images with a different camera view are utilized to estimate a position. The algorithm is tested using real infrared images acquired on the ground. The experimental results show that the method can be used for estimating the position of an aerial vehicle.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.2190-2192
• /
• 2001

가스 배관 진단 시스템은 배관 내부에 삽입되어 배관 내에 주입된 가스에 의해 추진되는 시스템으로 배관의 건설, 유지, 보수, 해체 등의 작업을 위한 여러 정보를 수집한다. 배관 진단을 위한 대표적인 센서로는 배관 내부의 찌그러짐(dent)과 주름(wrinkle)의 형태 및 크기를 측정하는 캘리퍼(caliper) 센서와 배관 외부의 파손을 측정하는 MFL(Magnetic Flus Leakage) 센서 그리고 배관 내의 환경 정보를 측정하기 위한 온도 센서와 압력 센서가 있다. 이러한 센서들로 수집된 정보를 활용하기 위해서는 정확한 위치 정보가 필요하므로 IMU(Inertial Measurement Unit)와 주행 거리계를 사용하는 결합 항법 시스템도 필요하다. 본 논문에서는 가스 배관 진단 시스템을 위한 항법 데이터 저장 시스템을 개발한다. 배관 진단 시스템의 특성상 일반적인 측정 센서는 700Hz 이상의 주기로 측정되고 항법 정보는 100Hz 주기 이상으로 측정되며 배관 내 이동 시간은 2시간에서 24시간 이상으로 다양하므로 많은 데이터를 효율적으로 저장할 수 있어야 한다. 따라서 데이터 저장 장치로는 DAT를 사용하게 되며 많은 센서 데이터를 실시간으로 저장하기 위해서 마스터-슬레이브 구조를 갖는 멀티 프로세서 구성을 이용한 항법 데이터 저장 시스템을 설계 제작하였다.

• Journal of Ocean Engineering and Technology
• /
• v.31 no.2
• /
• pp.164-169
• /
• 2017

Studies were performed on an ARS using SDINS's RLG and the geomatic sensor. To develop the ARS, experiments were performed to determine the characteristics of the RLG and geomatic sensor. Based on the results, to reduce the angular position errors of the RLG, which accumulate from the angular velocity data, an algorithm was studied that uses the Extended Kalman filter (EKF) to compensate the RLG data and geomatic sensor data. To verify the performance of the developed algorithm for reducing the cumulative angular errors, experiments that included the developed EKF were performed. Through these, it was shown that a drastic reduction in the angular errors of the RLG were achieved.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38C no.12
• /
• pp.1196-1206
• /
• 2013

In this paper, based on the information about navigation system of UAV with PTZ camera and 3D topography, algorithm able to show us in real-time UAV's geographical shooting location and automatically calculate superficial measure of the shooting area is proposed. And the method that can automatically estimate whether UAV is allowed to shoot a specific area is shown. In case of an UAV's shooting attempt at the specific area, obtainability of valid image depends on not only UAV's location but also information of 3D topography. As a result of the study, Ground Control Center will have real-time information about whether UAV can shoot the needed topography. Therefore, accurate remote flight control will be possible in real-time. Furthermore, the algorithm and the method of estimating shooting probability can be applied to pre-flight simulation and set of flight route.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.4
• /
• pp.47-52
• /
• 2006

Using the equivalent ARMA model representation of the mixed random errors, we propose Klaman filter design methods for aided INS(Inertial Navigation System) which contains the gyroscope mixed random errors. At first step, considering the characteristic of indirect feedback Kalman filter used in the aided INS, we perform the time difference of equivalent ARMA model. Next, according to the order of the time differenced ARMA model, we achieve the state space conversion of that by two methods. If the order of AR part is greater than MA part, we use controllable or observable canonical form. Otherwise, we establish the state apace equation via the method that several step ahead predicts are included in the state variable, where we can derive high and low order models depending on the variable which is compensated from gyroscope output. At final step, we include the state space equation of gyroscope mixed random errors into aided INS Kalman filter model. Through the simulation, we show that both the high and low order filter models proposed give less navigation errors compared to the conventional filter which assume the mixed random errors as white noise.

• International Journal of Control, Automation, and Systems
• /
• v.6 no.4
• /
• pp.534-543
• /
• 2008

To use the Global Positioning System (GPS) carrier phase measurement for precise positioning, the integer ambiguities at the early stage of most algorithms must be determined. Furthermore, if a precise positioning is to be applied to real time navigation, fast determination and validation methods for integer ambiguity are essential. In this paper, the Wald test that simultaneously determines and validates integer ambiguities is used with assistance of the Inertial Navigation System (INS) to improve its performance. As the Wald test proceeds, it assigns a higher probability to the candidate that is considered to be true at each time step. The INS information is added during the Wald test process. Large performance improvements were achieved in convergence time as well as in requiring fewer observable GPS satellites. To test the performance improvement of the Wald test with the INS information, experimental tests were conducted using a ground vehicle. The vehicle moved in a prescribed trajectory and observed seven GPS satellites. To verify the effect of the INS information on the Wald test, the convergence times were compared with cases that considered the INS information and cases that did not consider the INS information. The results show that the benefits of using the INS were emphasized as fewer GPS satellites were observable. The performance improvement obtained by the proposed algorithm was shown through the fast convergence to the true hypothesis when using the INS measurements.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2018.11a
• /
• pp.328-330
• /
• 2018

A floating body with a device that converts solar energy into electrical energy is moved by waves. To evaluate the safety of a floating body, measurement and interpretation of the float motion is required, which is generally based on 6 degrees of freedom motion. The 6 degree of freedom motion can be measured using MEMS (Micro-Electro Mechanical System), which features low power, small size and low cost. The key issue is, meanwhile, the low precision of the MEMS. In this study, the safety evaluation technique by analyzing the behavior of floating body using MEMS was examined. As a result of the study, it was found that the marine floating body can be modeled through the inertial measurement platform using the 3-axis accelerometer and the 3-axis gyroscope, and the safety of the float can be evaluated through this model.

• Korean Journal of Remote Sensing
• /
• v.37 no.5_3
• /
• pp.1349-1359
• /
• 2021

Acquisition of precise position and velocity information of GNSS-INS (Global Navigation Satellite System; Inertial Navigation System) sensors in obtaining SAR SLC (Single Look Complex) images from raw data using BPA (Backprojection Algorithm) was regarded decisive. Several studies on BPA were accompanied by Kalman Filter for sensor noise oppression, but often implemented once where insufficient information was given to determine whether the filtering was effectively applied. Multiple operation of Kalman Filter on GNSS-INS sensor was presented in order to assess the effective order of sensor noise calibration. FMCW (Frequency Modulated Continuous Wave)-SAR raw data was collected from twice airborne experiments whose GNSS-INS information was practically and repeatedly filtered via Kalman Filter. It was driven that the FMCW-SAR raw data with diverse path information could derive different order of Kalman Filter with optimum operation of BPA image restoration.