• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.525-528
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• 2003

In this paper, we present a novel idea to integrate low cost Inertial Measurement Unit(IMU) and Differential Global Positioning System (DGPS) for Telematics applications. As well known, low cost IMU produces large positioning and attitude errors in very short time due to the poor quality of inertial sensor assembly. To conquer the limitation, we present a bimodal approach for integrating IMU and DGPS, taking advantage of positioning and orientation data calculated from CCD images based on photogrammetry and stereo-vision techniques. The positioning and orientation data from the photogrammetric approach are fed back into the Kalman filter to reduce and compensate IMU errors and improve the performance. Experimental results are presented to show the robustness of the proposed method that can provide accurate position and attitude information for extended period for non-aided GPS information.

• 제어로봇시스템학회논문지
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• 제4권5호
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• pp.674-679
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• 1998

In this paper, a new coarse alignment algorithm is proposed for roughly determining the initial attitude of the vehicle. The algorithm, referred as two-step coarse alignment algorithm, computes roll and pitch angle of the vehicle using accelerometer outputs, and then determines yaw angle with gyro outputs. With the geometric relation between sensor outputs and attitude angles, the algorithm error is analytically derived and compared with the previous coarse alignment algorithm that computes a transformation matrix using accelerometer md gyro outputs simultaneously. The simulation is also performed by varying the sensor errors. The results show that the proposed two-step coarse alignment algorithm has better performance for east tilt angle.

• 대한원격탐사학회지
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• 제16권4호
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• pp.347-353
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• 2000

The purpose of this paper is to extract DEM (Digital Elevation Model) using KOMPSAT images. DEM extraction consists of three parts. First part is the modeling of satellite position and attitude, second part is the matching of two images to find corresponding points of them and third part is to calculate the elevation of each point by using the result of the first and second part. The position and attitude modeling of satellite is processed by using GCPs. Area based matching method is used to find the corresponding points between the stereo satellite images. The elevation of each point is calculated using the exterior orientation information obtained from sensor modeling and the disparity from the stereo matching. In experiment, the KOMPSAT images, 2592$\times$2796 panchromatic images are used to extract DEM. The experiment result show the DEM using KOMPSAT images.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1429-1432
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• 2005

This work is towards the development of a low-cost, small-sized inertial navigation system(INS) which consists of 3 accelerometers, 3 semiconductor gyros and a magnetic compass sensor. This paper explains in detail the structure of the developed system and proposes a 3 dimensional attitude estimation algorithm with Indirect Kalman Filter. The experiments are performed with the developed system attached to a 6 DOF robot for showing the effectiveness of the algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.788-792
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• 1993

The objective of this study is to develope a satellite dynamic simulator, which can test and analyze the performance of spacecraft attitude control, antenna pointing instruments, communication equipments and spacecraft components under the space environment. The satellite simulator can be used to predict the events such as malfunction and failure of satellites in space during operation and can be used to protect against emergencies. At first, the performance test system of attitude control is investigated which can simulate motion and verify stability of spacecraft. Our system consists of an attitude control main processor and a sub-processor including some real hardwares such as attitude sensors and actuators. In this paper, we describe the procedure of designing and manufacturing the dynamic simulator hardware, which consists of the central processor board, the sub-processor board and the sun sensor, and also communication between the components.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.141.6-141
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• 2001

This paper presents the attitude algorithm using Fuzzy technique to mix gyro information with accelerometer. The attitude angle calculated by the low-cost gyros only increases its error with time rapidly because of the integration process of the algorithm and large sensor error. It is known that the accelerometer output includes the attitude information of a vehicle and its information is more effective during low dynamic maneuver. Therefore it is needed to combine two information appropriately for obtaining the attitude information from low-cost MEMS inertial sensors. Because Fuzzy logic is very effective to make a decision of maneuvering state, it is applied to the mixed algorithm. It is shown by experiment ...

• 한국항해항만학회지
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• 제37권4호
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• pp.329-335
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• 2013

This paper is to develop the position error equations including the attitude errors, the errors of nadir and ship's heading, and the errors of ship's position in the free-gyro positioning and directional system. In doing so, the determination of ship's position by two free gyro vectors was discussed and the algorithmic design of the free-gyro positioning and directional system was introduced briefly. Next, the errors of transformation matrices of the gyro and body frames, i.e. attitude errors, were examined and the attitude equations were also derived. The perturbations of the errors of the nadir angle including ship's heading were investigated in each stage from the sensor of rate of motion of the spin axis to the nadir angle obtained. Finally, the perturbation error equations of ship's position used the nadir angles were derived in the form of a linear error model and the concept of FDOP was also suggested by using covariance of position error.

• 한국항공우주학회지
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• 제37권6호
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• pp.545-550
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• 2009

관성항법장치의 빠른 정렬을 위해 통상 센서(자이로, 가속도계) 데이터에 대해 전처리를 수행한다. 이때 외부진동이 인가되고 있는 환경에서 관성항법장치 정렬루프에서 사용하던 전처리 필터를 항법진입과 동시에 제거하면, 큰 초기 자세오차가 발생할 수 있다. 이에 본 논문에서는 이러한 초기 자세오차를 줄이기 위한 기법(차단주파수 변경, 실시간 자세추종)을 제안하였으며, 전산모의시험을 통해 검증하였다.

• 항공우주시스템공학회지
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• 제4권3호
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• pp.6-16
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• 2010

After the first successful Apollo program, many countries around the world launched their own programs for exploring the moon. This paper surveys various navigation and attitude control systems of several past lunar exploration programs for the purpose of preparing a program for the first Korean lunar probe. For this first we investigate successful programs by introducing the sensors and actuators used for these programs, particularly focusing on those of Clementine and SMART-1 of USA and EU, respectively. Then based on the study, we suggest the necessary components of navigation and attitude control systems suitable for our lunar probe program.

• 제어로봇시스템학회논문지
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• 제20권11호
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• pp.1098-1102
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• 2014

Localization of aerial vehicles and map building of flight environments are key technologies for the autonomous flight of small UAVs. In outdoor environments, an unmanned aircraft can easily use a GPS (Global Positioning System) for its localization with acceptable accuracy. However, as the GPS is not available for use in indoor environments, the development of a SLAM (Simultaneous Localization and Mapping) system that is suitable for small UAVs is therefore needed. In this paper, we suggest a vision-based SLAM system that uses vision sensors and an AHRS (Attitude Heading Reference System) sensor. Feature points in images captured from the vision sensor are obtained by using GPU (Graphics Process Unit) based SIFT (Scale-invariant Feature Transform) algorithm. Those feature points are then combined with attitude information obtained from the AHRS to estimate the position of the small UAV. Based on the location information and color distribution, a Gaussian process model is generated, which could be a map. The experimental results show that the position of a small unmanned aircraft is estimated properly and the map of the environment is constructed by using the proposed method. Finally, the reliability of the proposed method is verified by comparing the difference between the estimated values and the actual values.