• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.34-39
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• 1993

Presented in this paper is a complete error covariance analysis for strapdown inertial navigation system(SDINS). We have found that in SDINS the cross-coupling terms in gyrocompass alignment errors can significantly influence the SDINS error propagation. Initial heading error has a close correlation with the east component of gyro bias erro, while initial level tilt errors are closely related to accelerometer bias errors. In addition, pseudo-state variables are introduced in covariance analysis for SDINS utilizing the characteristics of gyrocompass alignment errors. This approach simplifies the covariance analysis because it makes the initial error covariance matrix to a diagonal form. Thus a real implementation becomes easier. The approach is conformed by comparing the results for a simplified case with the covariance analysis obtained from the conventional SDINS error model.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.557-565
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• 2004

The Korean space program was marked by the successful launching of a KSR-III liquid propelled sounding rocket. The Inertial Navigation System (INS) which carries out critical mission functions of navigation, guidance and control was domestically developed and perfectly certified through the flight test. The system consists of a strapdown inertial measurement, an onboard computer and flight software. This paper will describes the development works of the inertial navigation system, including top level system design, hardware and software. And it summarizes flight results.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.286-289
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• 1986

항법(navigation)은 기준좌표계에 대한 항체(vehicle)의 위치나 속도를 알아내기 위한 것으로 이를 위한 시스템이 관성항법장치(inertial navigation system-INS)이며 항법기능을 수행하기 위하여 항체에 놓여진 쎈서의 관성성질을 이용한다. INS는 specific force와 관성 각속도의 측정에서 얻은 데이타를 처리함으로 그 기능을 수행한다. 스트랩다운 INS(SINS)는 관성항법장치의 한 종류로 analytic INS라고도 하는데 기준좌표축을 유지하기 위하여 안정테이블을 사용하지 않고 쎈서들을 항체에 직접 부착시켜 초기상태와 현재상태와의 사이에 상대적인 회전방향을 해석적으로 계산한다. INS의 성능은 수많은 오차원(error source)의 함수로 주어지며 이 오차원 중에는 주위환경에 의한 것도 있고 INS 구성에 사용된 기구(instruments)와 관련된 것도 있다. INS 를 해석하는 목적은 항법의 정확도를 알아보는데 있으며 또한 각각의 오차원의 값을 추정하는 것도 부가적인 목적이 된다. 이러한 오차의 추정치는 사양(specification)을 모르는 부품의 성능을 식별하는데 사용될 수 있다. 따라서 INS를 해석함으로 INS를 구성하는 어떤 부품에 대한 성능이 어느정도 개선을 필요로 하는가 알 수 있다. 본 논문에서는 SINS의 오차원을 크게 고도계의 불확실성, 중력의 편향과 이상, 가속도계의 불확실성, 자이로의 불확실성의 네 그룹으로 나누어 상호분산해석(covariance analysis)방법으로 각 오차원이 시스템에 미치는 영향을 알아보았다.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.290-294
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• 1986

Initial alignment of gimballed INS is accomplished by the gyrocompassing techniques. These cannot be used in the case of strapdown system where the inertial instruments are directly strapped down to a vehicle frame. The basic objective of this paper is the development of digital methods performing the initial alignment of a SDINS from vibration and sway currupted data on the launch pad.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.28-41
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• 2002

The purpose of this paper is to show and define the performance, the system mechanization and the algorithm of the Strapdown Inertial Navigation System(SDINS). First, navigation equations are derived in the Earth Fixed mechanization and this mechanization apply to the two kinds of inertial measurement units which consist of same fiber optic gyros and different accelerometers(SDINS-1 and SDINS-2). Those two accelerometers have the different bias. To evaluate its performance, two kinds of tests have been performed - static motionless test, and rectangle-route moving test. The results of the moving test are compared with the results of Differential GPS which has an accuracy with ±2.0mm. and are presented in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1038-1044
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• 2016

In this paper, a SDINS(Strapdown Inertial Navigation System) rapid initial alignment technique robust to the pyro-shock in multi-launch rocket system is proposed. The proposed method consists of three steps. Firth, transfer alignment is performed to estimate misalignment between MINS(Master INS) and SINS(Slave INS), and the estimated misalignment is written in the memory when transfer alignment is completed. Next, the pre-filtering process is performed to get rid of the acceleration error induced by launcher vibration. Finally, the horizontal alignment is performed to compensate misalignment variation caused by pyro-shock. We verified the performance of the proposed alignment method comparing with the conventional transfer alignment method. The simulation shows that the proposed initial alignment technique improves alignment performance.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.1
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• pp.1231-1239
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• 2001

This paper presents a new leveling algorithm that estimates the initial horizontal angles composed of roll angle and pitch angle for a moving or stationary vehicle. The system model of the EKF is designed by linearizing the nonlinear Euler angle differential equation. The measurement models are designed for the moving case and for the stationary case, respectively. The simulation results show that the leveling algorithm is ade-quate not only for acquiring the initial horizontal angles of the vehicle in the motion with acceleration and rotation but also for the stationary one.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.1
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• pp.14-21
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• 2007

This paper proposes SDINS(strapdown inertial navigation system) transfer alignment method for vertical launcher using an adaptive filter in the ship. First, the velocity and attitude matching transfer alignment method is designed to align SDINS for vertical launcher. Second, the adaptive filter is employed to estimate measurement noise variance in real time using the residual of measurements. Because it is difficult to decide measurement noise variance when noise properties of the ship SDINS are changed. To verify its performance, it is compared with the EKF(Extended Kalman filter) using uncorrect measurement variance. The monte carlo simulation results show that proposed method is more effective in estimating attitude angle than EKF.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.8
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• pp.697-702
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• 2001

The ring laser gyro(RLG) has been used extensively in strapdown inertial navigation system(SDINS) because of the apparent of having wide dynamic range, digital output and high accuracy. The dithered RLG system has dynamic motion at sensor level, caused by the dithering motion to overcome the lock-in threshold. In this case, an attitude error is produced by not only the true coning of the vehicle motion but also the pseudo coning of the sensor motion. This paper describes the definition of the multi-frequency coning motion and its noncommutativity error to reject the pseudo coning error produced by the sensor motion such as the dithered RLG. The simulation results are presented to minimize the multi-frequency coning error.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.2
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• pp.239-246
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• 2004

In this paper, we develop and implement a high integrity GNC(Guidance, Navigation, and Control) system, based on the combined use of the Global Positioning System (GPS) and an Inertial Measurement Unit (IMU), for autonomous land vehicle applications. This paper highlights guidance for the predetermined trajectory and navigation with detection of possible faults during the fusion process in order to enhance the integrity of the navigation loop. The implementation of the GNC system to the autonomous land vehicle presented with fault detection methodology considers high frequency faults from the GPS receiver caused by shadowing and multipath error The implementation, based on a low-cost, strapdown INS aided by standard GPS technology, is described. The results of the field test in the urban environment are presented and showed effectiveness of the GNC system.