• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.295-297
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• 1986

In this study, the strap down INS on an earth satellite launch vehicle is simulated with different computing cycles between processing the IMU signals and the navigation computation. At the time of separation of booster, error are discussed. The acceptable computing cycles can be determined by simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.42-46
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• 2006

As an application of SDINS/GPS integration for its synergistic results, the SDINS alignments utilizing GPS carrier phase rate measurements. A measurement model of GPS carrier phase rate is derived in order to be used with SDINS alignment process. For in-flight alignment, the performance of the suggested SDINS/GPS integration method is analyzed using the covariance analysis and its results are confirmed by those of van test. Consequently, it is shown that all states of the SDINS integrated system by utilizing GPS carrier phase rate measurements can be estimated more efficiently than a general SDINS/GPS during in-flight alignment.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.3
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• pp.368-377
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• 2009

In this paper we study the gyro bias calibration method of SDINS(Strap-Down Inertial Navigation System). Generally, SDINS's calibration is performed in 2-axis(or 3-axis) rate table with chamber for varying ambient temperature. We assumed that the majority of calibration-parameter except for gyro bias is knowned. During gyrobias calibration procedure, it can be induced some disturbances(accelerometer's short-term error induced rate table rotation and anti-vibration mount's rotation). In these cases, old gyro-bias calibration methods(using velocity error or attitude error) have an error, because these disturbances are not detectable at the same time. So that, we propose a new gyro-bias calibration method(heading error minimizing using equivalent linear transformation) that can detect anti-vibration mount's rotation. And we confirm efficiency of the new gyro-bias calibration method by simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.1
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• pp.72-78
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• 2007

Determination of the local vertical is not trivial for a moving vehicle and in general will require corrections for the Earth geophysical deflection. The vehicle's local vertical can be estimated by INS integration with initial alignment in SDINS(Strap Down INS) system. In general, the INS has drift error and it cause the performance degradation. In order to compensate the drift error, GPS/INS augmented system is widely used. And in the event that GPS is denied or unavailable, celestial navigation using star tracker can be a backup navigation system especially for the military purpose. In this celestial navigation system, the vehicle's position determination can be achieved using more than two star trackers, and the accuracy of position highly depends on accuracy of local vertical direction. Modern tilt sensors or accelerometers are sensitive to the direction of gravity to arc second(or better) precision. The local gravity provides the direction orthogonal to the geoid and, appropriately corrected, toward the center of the Earth. In this paper the relationship between direction of center of the Earth and actual gravity direction caused by geophysical deflection was analyzed by using precision orbit simulation program embedded the JGM-3 geoid model. And the result was verified and evaluated with mathematical gravity vector model derived from gravitational potential of the Earth. And also for application purpose, the performance variation of pure INS navigation system was analyzed by applying precise gravity model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1742-1747
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• 2015

An improved transfer alignment method for a strap-down inertial navigation system (SDINS) is presented here. The alignment accuracy in conventional method is vulnerable to the data latency of a Master INS (MINS) in high maneuverable platforms. We propose a time delay compensation equation considering higher-order terms in the attitude measurement equation of the Kalman filter. The equation incorporates additional information including angular rate, angular acceleration and linear acceleration from the MINS. Simulation results show that the transfer alignment accuracy is significantly improved in the high dynamic environment by incorporating the latency compensation technique.