• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.433-439
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• 2018

In this paper, a SDINS(strapdown inertial navigation system) rapid initial alignment technique with adaptive time delay compensation is proposed. The proposed method consists of two steps. In first step, misalignment and data latency are estimated by conducting pre-transfer alignment. Then, hybrid alignment is designed to rapidly find the misalignment changes induced by pyro-shock. To improve the performance of hybrid alignment, adaptive time delay compensation method is suggested. We verify the performance improvement of the proposed alignment scheme comparing with the conventional transfer alignment method by van test. The test result shows that the proposed alignment technique improves alignment performance.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.493-495
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• 2004

In this paper, shows a research in accordance with the design the implementation of the localization system for mobile robot using INS(Inertial Navigation System) and GPS(Global Positioning System). First, a Strapdown Inertial Navigation System : SDINS is designed and implemented for low speed walking robot, by modifying Inertial Navigation System which is widely used for rocket, airplane, ship and so on. In addition, thesis proposes the localization of robot with the method of loosely coupled method by using Kalman Filter with INS/GPS integrated system to utilize assumed position and steed data from GPS.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.4
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• pp.56-71
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• 1987

Determination of navigation variables (latitude, longitude, and altitude) near the earth's surface is termed 'Terrestrial Navigation'. The quantities that are measured inertially are the total acceleration (or the integral fo this acceleration over a fixed time interval) and the total angular rate (or the integral of this angular rate over the same time interval). These measurements when suitably compensated can be manipulated to yield the navigation variables. Hence, it is essential that the initial values of position, orientation and velocity are accurately set up during the initial alignment process. Initial alignment of gimballed inertial navigation system ( GINS) is accomplished by gyrocompassing techniques. These cannot be used, in the case of strapdown inertial navigation system(SDINS), where the inertial instruments are directly strapped down to a vehicle frame. The basic objective of this paper is the development of digital method for the determination of the initial axes erection of a SDINS from vibration and sway currupted data on the launch pad.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.138-145
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• 2000

In this paper an initial alignment algorithm for a strapdown inertial navigation system is implemented using a RISC CPU board. The algorithm computes roll pitch and yaw angles of the direction cosine matrix utilizing measured components of the specific force and earth rate when the navigation system is stationary. The coarse alignment algorithm is performed first and then the fine alignment algorithm containing a 3rd-order gyrocompass loop follows. The experimental set consists of an IMU a CPU board and a monitoring system Experimental results show that the implemented algorithm can be utilized in navigation systems.

• 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 Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.132-140
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• 2006

In this paper, a new fault detection method for the extended Kalman filter, which uses a N-step predictor, is proposed. The N-step predictor performs the only time propagations for N-step intervals without measurement updates and its output is used as a monitoring signal for the fault detection. A consistency between the extended Kalman filter and the N-step predictor is tested to detect a fault. A test statistic is defined by the difference between the extended Kalman filter and the N-step predictor. The proposed method is applied to strapdown inertial navigation system (SDINS). By computer simulation, it is shown that the proposed method detects a fault effectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.419-425
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• 2007

A rapid one-shot alignment method of the Strapdown INS (SDINS) for a vertical launch is proposed. The proposed alignment is performed using the accelerometer output of the Slave INS and the attitude of the Master INS. To improve the accuracy and the speed of the alignment, the equivalent linear transformation and the pre-filtering method are developed. Experiment results show that the proposed method is effective in improving the accuracy and the speed of the alignment.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.241-245
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• 2005

Strapdown inertial navigation system (SINS) integrated with astronavigation system (ANS) yields reliable mission capability and enhanced navigational accuracy for spacecrafts. The theory and characteristics of integrated system based on unscented Kalman filtering is investigated in this paper. This Kalman filter structure uses unscented transform to approximate the result of applying a specified nonlinear transformation to a given mean and covariance estimate. The filter implementation subsumed here is in a direct feedback mode. Axes misalignment angles of the SINS are observation to the filter. A simple approach for simulation of axes misalignment using stars observation is presented. The SINS error model required for the filtering algorithm is derived in space-stabilized mechanization. Simulation results of the integrated navigation system using a medium accuracy SINS demonstrates the validity of this method on improving the navigation system accuracy with the estimation and compensation for gyros drift, and the position and velocity errors that occur due to the axes misalignments.