• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.131-139
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• 2000

A design of CPS attitude determination system is described in this paper. The designed system is a low cost high precision 24 channel single frequency GPS(Global Positioning System) receiver which provides a precise absolute heading and pitch (or roll) as well as a position. It uses commercial chip-set and consists of two RF parts, two signal-tracking parts, a processor, memory parts and I/Os. In order to determine precise attitude, accurate carrier phase measurements and an efficient integer ambiguity resolution method are required. To meet these requirements, a PLL (Phase Locked Loops) is designed, and an algorithm called ARCE (Ambiguity Resolution with Constraint Equation) is adopted. The hardware and software structure of the system will be described, and the performance evaluated under various conditions will be presented. The test results will promise that more reliable navigation system be possible because the system provides all navigational information such as position, velocity, time and attitude.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.2
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• pp.88-94
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• 2002

This paper describes attitude determination algorithm for the low earth orbit(LEO) spacecraft using stellar inertial sensors. The cascaded gyro/star tracker extended Kalman filter is constructed to fuse two sensor data. And then the smoothing of the measurement are proposed for an unreasonable jump of star tracker. The smoothing algorithm for the rejection of star tracker error jumps is designed by scalar adaptive filter. The proposed algorithms operate to process the measurement of gyro/star tracker Kalman filter, therefore, it is comparatively simple to apply these methods to other integration systems. Simulations to gyro/star tracker integrated system show that the proposed method is effective.

• Journal of Advanced Navigation Technology
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• v.2 no.1
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• pp.3-10
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• 1998

GPS is one of the main navigation systems. In these days, the application scope of GPS is extended to attitude determination using Differential GPS(DGPS) technique and Cycle Ambiguity resolution technique. In this paper, we propose an attitude determination algorithm using Kalman filter through double differenced measurement equation which is not for users with GPS patch antennas, but for users with low-priced GPS receivers. This paper also shows the simulation results and the effectiveness of proposed algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.6
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• pp.587-594
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• 2008

In this paper, an efficient integer ambiguity resolution method for GNSS attitude determination system is described. The proposed method solves the integer least-squares with quadratic equality constraints(ILSQE) problem and shows an expansion of the LAMBDA method can be used to solve it. The solution of ILSQE is shown and an efficient implementation with a LAMBDA based method is given. The method is compared with some other methods. The results of static and dynamic tests show the dramatic improvement of the success rates of integer ambiguity resolution.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.10
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• pp.1025-1031
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• 2007

GPS is widely used for positioning applications and attitude of a vehicle can be found also with multiple antennas. However, extremely weak signal level prevents GPS from indoor operation. DR with accelerometers and gyros and landmark based localization method used for indoor applications increase complexity and cost. In this paper, a simple but very efficient ultrasound based attitude determination system which determines both position and attitude in WSN is given. The range between transmitter and receivers are measured using the arrival time difference between ultrasound and RF signal. The 3 dimensional positions can be found using more than 3 range measurements. Furthermore, if more than 2 transmitters are used, the attitude can be determined using the baseline vectors obtained by differencing transmitter and receiver positions. The prototype system is implemented to evaluate the performance of the proposed method. In addition, an error analysis shows the relation between the attitude error and basel me length, quality of measurement and orientation of a vehicle. The static and dynamic experiments performed by micro mobile robot shows accurate position with less than 1.5cm error and attitude with less than 1 degree error can be obtained continuously with 20cm baseline. It is expected that these results can be adapted without modification to indoor applications such as home cleaning robot and autonomous wheelchair maneuvering.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.271-275
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• 2006

This paper describes the design and realization of full attitude system based on MEMS IMU and GPS carrier phase. The work can be divided into two parts: First, initial heading is determined by using two GPS receivers. And this paper discusses the usage of space geometry conditions to reduce the range of ambiguity search. The method presented in this paper was tested on the static. On the static condition, an accuracy better than 0.06 degrees for heading for 3.48m long baseline has been achieved. Integration of GPS and low cost MEMS IMU are used to realize the real-time heading attitude system. Second, level attitude (pitch and roll) is determined using the method of frequency-velocity for the feedback control. At the same time, the method using the attitude based on MEMS IMU to help determination of the range of ambiguity search is proposed. The results done on the sea show that an alternative means to provide real-time, cost-effective, accurate and reliable attitude information for attitude surveys. Though motivated by a big ships application, the design can be applied to other vehicles.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.45-50
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• 2005

To determine precise position GPS carrier phase measurements are used. In addition, the multi-antenna system consisting of 2 or more GPS antennas can make attitude determination effectively. When GPS carrier phase measurements are used the integer ambiguity must be fixed. The success rate is used to validate the integer ambiguity. For LEO satellite attitude determination the double difference carrier phase measurements are used, the success rate is calculated using the covariance matrix and the measurement matrix. The constraint that LEO satellite position vector and attitude vector is orthogonal is suggested for improving the success rate. The LEO satellite orbit model is KITSAT3. The results of the simulation are shown and analyzed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.300-308
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• 2010

In order to accelerate the evolution of faster, better, cheaper spacecraft, it is evident that greatly enhanced general-purpose attitude determination methods are needed Currently, star tracker sensors based on charge coupled devices (CCD) or active pixel sensors(APS) enable one to obtain the best spacecraft attitude estimation among the existing sensors for attitude determination. In this paper, basic principles of star tracker technology are explained including major issues arising in design and development of star tracker. Also, an historical overview and worldwide survey associated with various star trackers from star scanner through microelectromechanical system(MEMS)-based star tracker is offered.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.1
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• pp.74-79
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• 2002

A fast and practical method is proposed to resolve the half cycle ambiguity by comparing data sequences from multiple antennas. The method uses the fact that demodulated data sequences from multiple antennas are identical for the same SV (Satellite Vehicle). The performance of the proposed method is evaluated using an attitude determination system. the test results show that the half cycle ambiguity can be resolved within a few bit periods after carrier lock and a seamless attitude is obtained.

• Journal of Astronomy and Space Sciences
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• v.30 no.1
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• pp.1-10
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• 2013

An integrated orbit and attitude control algorithm for satellite formation flying was developed, and an integrated orbit and attitude software-in-the-loop (SIL) simulator was also developed to test and verify the integrated control algorithm. The integrated algorithm includes state-dependent Riccati equation (SDRE) control algorithm and PD feedback control algorithm as orbit and attitude controller respectively and configures the two algorithms with an integrating effect. The integrated SIL simulator largely comprises an orbit SIL simulator for orbit determination and control, and attitude SIL simulator for attitude determination and control. The two SIL simulators were designed considering the performance and characteristics of related hardware-in-the-loop (HIL) simulators and were combined into the integrated SIL simulator. To verify the developed integrated SIL simulator with the integrated control algorithm, an orbit simulation and integrated orbit and attitude simulation were performed for a formation reconfiguration scenario using the orbit SIL simulator and the integrated SIL simulator, respectively. Then, the two simulation results were compared and analyzed with each other. As a result, the user satellite in both simulations achieved successful formation reconfiguration, and the results of the integrated simulation were closer to those of actual satellite than the orbit simulation. The integrated orbit and attitude control algorithm verified in this study enables us to perform more realistic orbit control for satellite formation flying. In addition, the integrated orbit and attitude SIL simulator is able to provide the environment of easy test and verification not only for the existing diverse orbit or attitude control algorithms but also for integrated orbit and attitude control algorithms.