http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
롤피치 제한 조건에 강인한 가중 최소자승법 기반 마그네토미터 캘리브레이션 기법
전태형,이정근,Jeon, Tae-Hyeong,Lee, Jung-Keun 한국센서학회 2017 센서학회지 Vol.26 No.4
Magnetometer calibration must be performed before the use of three-axis magnetometers to ensure the accuracy of orientation estimation. Recently, one of the most popular calibration approaches is the ellipsoid fitting technique due to its high performance in calibration. To date, in fact, performances of the existing ellipsoid fitting methods have been evaluated with full range rotation data. However, in case of the calibration of magnetometers attached to vehicles, ships, and planes, it is very difficult to collect the full range rotation data since their allowable ranges in terms of roll and pitch are limited to small. This constraint may result in serious performance degradation of some ellipsoid fitting algorithms. Therefore, to be practical, this paper proposes a weighted least square-based magnetometer calibration method that is robust in roll-pitch limited conditions. Furthermore, the proposed method is a linear approach and thus is free from the well-known initial value issue in nonlinear approaches. Experimental results show the superiority of the proposed method to other ellipsoid-fitting calibration methods.
전태형(Tae Hyeong Jeon),이정근(Jung Keun Lee) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.1
Three-axis magnetometers are widely used in various fields requiring azimuth information. However, accuracy of azimuth estimation based on magnetometer signals may be degraded because of errors such as offset, scale factor, nonorthogonality, hard-iron distortion, and soft-iron distortion. Recently, several ellipsoid-fitting calibration techniques have been proposed and have received much attention. However, comparative analysis of calibration accuracies between these techniques has not been conducted. This study compared and analyzed performance of four ellipsoid-fitting magnetometer calibration techniques such as the linear least square method, the two-step algorithm, and two different nonlinear least square methods. Our analysis and experimental results reveal superiority of the linear least square method compared to other methods in terms of calibration accuracy as well as ease of use in practice.
IMU-Based Joint Angle Estimation Under Various Walking and Running Conditions
Tae Hyeong Jeon(전태형),Jung Keun Lee(이정근) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.12
Previous studies on joint angle estimation have been restricted to slow-speed level walking conditions, even though slope walking and running elicit unique biomechanical characteristics. Measurements were mostly based on an optical motion capture system despite in-the-lab limitation of measurement technique. The contribution of this study is twofold: (i) to propose a joint angle estimation method by applying a state-of-the-art parallel Kalman filter based on an inertial measurement unit (IMU) that can overcome in-the-lab limitation, and (ii) to demonstrate its application to level walking condition as well as slope walking and running conditions to fill a gap in joint kinematics literature. In particular, this study focuses on knee flexion/extension and ankle dorsiflexion/plantarflexion angles at various speed variations. The parallel Kalman filter applied in the proposed method can compensate external acceleration through Markov-chain-based acceleration modeling, that may enhance joint estimation performance in high speed walking conditions. To validate the proposed estimation method, an optical motion capture system was used as reference. In addition, patterns for each condition were investigated to identify and evaluate presence of classifying features.
전태형(Tae Hyeong Jeon),이정근(Jung Keun Lee) Korean Society for Precision Engineering 2019 한국정밀공학회지 Vol.36 No.7
With regard to 3D orientation estimation based on IMMU (Inertial Magnetic Measurement Unit) signals, the yaw estimation accuracy may be significantly degraded as a result of magnetic distortions. Consequently, several yaw estimation Kalman filters (KFs) possessing distortion compensation mechanisms have been proposed. However, majority of the conventional methods fail to effectively curb inaccuracies due to distortion when magnetic fields are extremely distorted. In this paper, we propose a new KF projecting a kinematic constraint to minimize yaw estimation errors induced by magnetic distortions. After the measurement update using magnetometer signals, the proposed method additionally corrects the yaw estimation through projection of a kinematic constraint on a conventional unconstrained KF. Experimental results show that the proposed KF outperformed the conventional KF by approximately 52-67%.
안드로이드 스마트폰의 이중 주파수 GNSS 의사거리 기반 해상 측위정확도 성능 분석
서기열,김영기,전태형,손표웅,Seo, Kiyeol,Kim, Youngki,Jeon, Tae-Hyeong,Son, Pyo-Woong 한국정보통신학회 2021 한국정보통신학회논문지 Vol.25 No.11
안드로이드 기반 스마트폰은 GNSS (Global Navigation Satellite System) 신호를 수신하여 위치를 결정하고, GNSS 원시계측정보를 사용자에게 제공하고 있다. 현재까지 안드로이드 기기에서 안드로이드 9.0 기준으로 가용한 다중 GNSS 신호는 GPS, GLONASS, Galileo, BeiDou, QZSS를 포함하고 있다. 본 논문에서는 가용한 다중 GNSS 신호를 이용하여, 해상 이용자를 위한 이중 주파수 안드로이드 스마트폰의 의사거리 기반 다중 GNSS 측위정확도 성능을 비교 분석하였다. 선박에 이주파 수신이 가능한 스마트폰을 설치하고, 해상 환경에서의 멀티 GNSS 원시정보를 계측하여 스마트기기별, GNSS 별, 의사거리 기반 이주파 측위성능 결과를 비교하였다. 더 나아가 본 측위 성능 결과가 해양 항법 이용자를 위한 IMO의 HEA 요구성능을 충족할 수 있을지에 대해 분석하였다. 해상 실험 결과로부터 이주파 GNSS 신호를 지원하는 스마트폰의 경우 6미터(95%) 정도의 측위정확도를 얻을 수 있었으며, IMO에서 요구하는 10미터 이내의 HEA 측위정확도 성능을 달성할 수 있음을 확인할 수 있었다. Android-based smartphones receive the global navigation satellite system (GNSS) signals to determine their location and provide the GNSS raw measurement to users. The available GNSS signals on the current Android devices are GPS, GLONASS, Galileo, BeiDou, QZSS. This research has analyzed the performance of multi-GNSS position accuracy based on the pseudorange of the smartphone for maritime users. Smartphones capable of receiving dual-frequency are installed on a ship, and multi-GNSS raw information in maritime environment was measured to present the results of comparing the GNSS pseudorange-based dual-frequency positioning performance for each smarphone. Furthermore, we analyzed whether the results of the positioning performance can meet the HEA requirement of IMO for maritime navigation users. As the results of maritime experiment, it was confirmed that in the case of the smartphones supporting the dual-frequency, the position accuracy within 6 meters (95%) could be obtained, and the HEA position accuracy performance within 10 meters (95%) required by IMO could be achieved.
자기 왜곡에 의해 야기되는 방향각 추정 불확실성을 감소시키기 위한 구속형 AHRS 칼만 필터
이정근(Jung Keun Lee),전태형(Tae Hyeong Jeon) 제어로봇시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.5
An attitude and heading reference system (AHRS) based on inertial and magnetic measurement unit (IMMU) signals has a critical problem, in that the heading estimation accuracy can be degraded by magnetic distortion-induced uncertainty related to magnetometer signals. Although several distortion compensation mechanisms have been developed to deal with this issue and they showed improvement to some extent, they have an inherent limitation in that magnetic distortion-induced uncertainty is inevitable in many environments. This paper proposes a constrained AHRS Kalman filter (KF) to reduce magnetic distortioninduced uncertainty in heading estimation by exploiting the acceleration-level kinematic constraint of a spherical joint. In particular, this paper focuses on a two-link system that is connected by a spherical joint, where one link is exposed to magnetic distortions and the other link is not. The proposed KF improves the heading estimation of the former link using constraint projection. Our experimental results showed the superiority of the proposed KF to conventional unconstrained KF: The root mean square errors of the heading estimation with the proposed KF were 0.75° in Test 1 and 1.85° in Test 2, while those from the conventional KF were 3.50° in Test 1 and 10.73° in Test 2.
비정렬과 약성 왜곡을 고려한 타원체 피팅 방식 지자기 센서 캘리브레이션
이정근(Jung Keun Lee),전태형(Tae Hyeong Jeon) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.12
The calibration of magnetometers is essential for achieving accurate heading estimations as magnetometer signals can often be corrupted due to various types of magnetic distortions such as offset, sensitivity, hard-iron distortion, misalignment, and soft-iron distortion. In literature, most calibration methods have focused on the former three distortions, while the latter two have received little attention in spite of their importance. This paper proposes a novel ellipsoid-fitting magnetometer calibration method that considers misalignment and soft-iron distortion. A complete calibration model with 24 parameters is established based on an ellipsoid restriction and experimental results show that the proposed method outperformed two other ellipsoid-fitting calibration methods in terms of the root mean squared errors of heading estimations under two different distorted conditions.