• 한국항공우주학회지
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• 제41권6호
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• pp.481-487
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• 2013

GPS/INS 항법시스템의 설치에 있어서 대다수의 경우 GPS 수신기 안테나는 차량의 외부에 설치하게 되고 IMU는 내부에 설치하게 된다. Lever Arm 오차는 이와 같이 센서의 장착 위치 차이로 인하여 발생하는 구조적인 오차에 해당한다. Lever Arm 오차는 항법성능에 직접적으로 영향을 주기 때문에 적절한 보상이 반드시 필요하다. 본 논문에서는 GPS와 INS의 속도 측정치를 활용하여 임의의 위치에 장착된 두 센서의 Lever Arm 오차를 효과적으로 추정하고 보상하는 방식을 제안하였다. 실험을 통해 제안한 알고리즘의 타당성을 검증하였으며, 항체의 회전운동 구간에서 Lever Arm 오차 보상이 특히 중요함을 보였다.

• 한국항공우주학회지
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• 제40권12호
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• pp.1086-1092
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• 2012

항공 산업의 발전에 따라 정밀하고 신뢰성 높은 항법 정확도를 제공하기 위하여 DGPS/INS 복합항법 장치에 대한 많은 연구가 수행되고 있다. 이러한 항법 시스템의 항법 정확도는 항공기의 안전성과 신뢰성에 직접적인 영향을 끼치기 때문에 항법 시스템의 비행시험 검증은 매우 중요하다. 특히 DGPS/INS 복합항법 장치와 같은 높은 수준의 위치 정확도를 가지는 항법시스템을 검증하기 위해서는 보다 정확한 비행 항법 성능 평가기법이 필요하다. 항법 성능 검증은 DGPS/INS보다 정밀한 항법 정확도를 가지는 기준 궤적과의 비교 분석을 통해 이루어지며 기준 수신기는 수 cm수준의 CDGPS 후처리 기법이 가능한 GPS 수신기를 사용해야 한다. 일반적으로 DGPS/INS 복합항법 장치의 출력 점은 항공기의 무게중심점으로 GPS 안테나의 위치를 출력하는 GPS 수신기와 다르기 때문에 출력데이터의 가공없이 성능 평가를 진행할 경우 추정 오차에 안테나 위치와 항공기의 무게중심점간 거리 오차가 포함된다. 따라서 보다 정확한 항법 성능 평가를 위하여 기준 궤적 생성을 위한 GPS 수신기의 Lever Arm 보정이 필요하다. 본 논문에서는 DGPS/INS 복합항법장치의 비행항법 성능 검증을 위하여 기준궤적의 Lever Arm 보정을 포함한 비행시험 성능평가 절차 및 비행 시험 결과를 제시한다.

• Journal of Positioning, Navigation, and Timing
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• 제1권1호
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• pp.45-49
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• 2012

The flight performance evaluation of navigation system is very significant because the reliability of navigation data directly affect the safety of aircraft. Especially, the high-level navigation system such as DGPS/INS, need more precise flight performance evaluation method. The performance analysis is evaluated by comparing between the navigation system in aircraft and reference trajectory which is more precise than navigation system in aircraft. In order to verify DGPS/INS performance of m-level, the GPS receiver, which is capable post-processed Carrier-phase Differential GPS(CDGPS) method of cm-level, have to be used as reference system. The DGPS/INS is estimated the Center of Gravity (CG) point of aircraft to offer precise performance while the reference system is output the position of GPS antenna which is mounted on the outside of aircraft. Therefore, in order to more precise performance evaluation, it needs to compensate the lever arm and coordinates transformation. This paper use quaternion and Direct Cosine Matrix(DCM) methods as coordinate transformation matrix in lever arm compensation of CDGPS reference trajectory. And it compares NED errors of DCM and quaternion transformation in lever arm of reference trajectory via DGPS/INS result.

• 전기학회논문지
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• 제67권12호
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• pp.1648-1656
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• 2018

The configuration of redundant inertial sensors are very important when considering navigation performance and fault detection and isolation (FDI) performance. By constructing a redundant sensor system using multiple inertial sensors, it is possible to improve the navigation performance and fault detection and isolation performance, which are highly related to the sensor configuration and allocation. In order to deploy multiple MEMS inertial measurement units effectively, a configuration and allocation methods considering navigation performance, fault detection and isolation performance, and lever arm effect in one plane are presented, and the performance is analyzed through simulation in this research. From the results, it is confirmed that the proposed configuration and allocation method can improve navigation, FDI, and lever arm effect rejection performances more effectively by more than 70%.

• 제어로봇시스템학회논문지
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• 제19권10호
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• pp.941-946
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• 2013

In this paper, an enhanced method for attitude determination is proposed for systems using an IMU (Inertial Measurement Unit). In attitude determination with IMU, it is generally assumed that the IMU can be located in the center of gravity on the vehicle. If the IMU is not located in the center of gravity, the accelerometers of the IMU are disturbed from additive accelerations such as centripetal acceleration and tangential acceleration. Additive accelerations are derived from the lever arm which is the distance between the center of gravity and the position of the IMU. The performance of estimation errors can be maintained in system with a non-zero lever arm, if the lever arm is estimated to remove the additive accelerations from the accelerometer's measurements. In this paper, an estimation using Kalman filter is proposed to include the lever arm in the state variables of the state space equation. For the Kalman filter, the process model and the measurement model for attitude determination are made up by using quaternion. In order to evaluate the proposed algorithm, both of the simulations and the experiments are performed for the simplified scenario of motion.

• 전자공학회논문지
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• 제50권1호
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• pp.276-284
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• 2013

본 논문에서는 관성항법시스템의 전달정렬시 속도정합 알고리듬에 대하여 지렛대 거리 오차의 가관측성 분석을 수행하였다. 이를 위해 지렛대 거리 오차를 포함한 칼만필터 상태 변수를 모델링하였고 측정 방정식을 구성하였다. 가관측성 분석 방법으로는 SOM을 이용하였고 다양한 항체의 운항 조건들에 대하여 가관측성 분석을 수행하였다. 기존의 지렛대 거리 오차를 포함한 가관측성 분석 기법들은 시뮬레이션을 통한 분석이 주를 이룬 반면에 본 논문에서는 상태 변수들이 완전 가관측하기 위한 항체의 운항 조건을 해석적으로 제시하였다. 그리고 시뮬레이션을 수행하여 분석 결과를 검증하였다.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1253-1267
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• 2005

Misalignment can be an important problem in the integration of GPS/INS. Observability analysis of the alignment errors in the integration of low-grade inertial sensors and multi-antenna GPS is presented in this paper. A control-theoretic approach is adopted to study the observability of time-varying error dynamics models. The relationship between vehicle motions and the observability of the errors in the lever arm and relative attitude between GPS antenna array and IMU is given. It is shown that alignment errors can be made observable through maneuvering. The change of acceleration makes the components of the relative attitude error that are orthogonal to the direction of the acceleration change observable. The change of angular velocity makes the components of the lever arm error that are orthogonal to the direction of the angular velocity observable. The motion of constant angular velocity has no influence on the estimation of the lever arm.

• Journal of Positioning, Navigation, and Timing
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• 제11권3호
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• pp.199-208
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• 2022

Inertial Navigation System (INS)/Global Navigation Satellite System (GNSS) integrated navigation system can be used for land vehicle navigation. When the GNSS signal is blocked in a dense urban area or tunnel, however, the problem of increasing the error over time is unavoidable because navigation must be performed only with the INS. In this paper, Non-Holonomic Constraints (NHC) information is utilized to solve this problem. The NHC may correct some of the errors of the INS. However, it should be noted that NHC information is not applicable to all areas within the vehicle. In other words, the lever arm effect occurs according to the distance between the Inertial Measurement Unit (IMU) mounting position and the NHC effective point, which causes the NHC condition not to be satisfied at the IMU mounting position. In this paper, an INS/GNSS/NHC integrated navigation filter is designed, and this filter has a function to compensate for the lever arm effect. Therefore, NHC information can be safely used regardless of the vehicle's driving environment. The performance of the proposed technology is verified through Monte-Carlo simulation, and the performance is confirmed through experimental test.

• International Journal of Control, Automation, and Systems
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• 제4권2호
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• pp.247-254
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• 2006

For more accurate navigation, lever arm compensation is considered. The compensation method for GPS and an odometer is introduced and new compensation methods are proposed for an odometer to consider the effect of coordinate transformation errors and the scale factor error. The methods are applied to a GPS/INS/odometer integrated system and the simulation and experimental results show its effectiveness.

• 제어로봇시스템학회논문지
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• 제13권12호
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• pp.1243-1251
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• 2007

In this paper a study on the simplified observability analysis of GPS/INS is introduced. Errors for the position, velocity, attitude, gyro and accelerometer biases, and lever arm between GPS antenna and inertial sensors are considered in the observablity analysis. From the error dynamics model in which relatively small terms are neglected, simple observability conditions are obtained such that the observability of GPS/INS is determined by the test on the attutude, gyro bias, and lever arm. Unobservable errors for the position, velocity, and accelerometer bias are determined by those for the attitude, gyro bias, and lever arm. The simplified observability conditions are applied to a constant speed horizontal motion. It is shown that there are seven unobservable modes for the motion including the vertical component of gyro bias. The analytic observability analysis results are confirmed with a covariance simulation.