• 한국해양공학회지
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• 제17권6호
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• pp.83-90
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• 2003

This paper presents an underwater hybrid navigation system for a semi-autonomous underwater vehicle (SAUV). The navigation system consists of an inertial measurement unit (IMU), and a Doppler velocity log (DVL), accompanied by a magnetic compass. The errors of inertial measurement units increase with time, due to the bias errors of gyros and accelerometers. A navigational system model is derived, to include the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 20. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors, and correct the state equation when the measurements are available. Simulation was performed with the 6-d.o,f equations of motion of SAUV, using a lawn-mowing survey mode. The hybrid underwater navigation system shows good tracking performance, by updating the error covariance and correcting the system's states with the measurement errors from a DVL, a magnetic compass, and a depth sensor. The error of the estimated position still slowly drifts in the horizontal plane, about 3.5m for 500 seconds, which could be eliminated with the help of additional USBL information.

• International Journal of Aeronautical and Space Sciences
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• 제11권3호
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• pp.234-239
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• 2010

The utilization of micro-electro-mechanical system (MEMS) gyros and accelerometers in low-level inertial measurement unit (IMU) influences cost effectiveness in a positive way under the condition that device error characteristics are fully calibrated. The conventional calibration process utilizes a rate table; however, this paper proposes a new method for achieving reference calibration data from the natural motion of pendulum to which the IMU undergoing calibration is attached. This concept was validated with experimental data. The pendulum angle measurements correlate extremely well with the solutions acquired from the pendulum equation of motion. The calibration data were computed using the regression method. The whole process was validated by comparing the measurement from the 6 sensor components with the measurements reconstructed using the identified calibration data.

• International journal of advanced smart convergence
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• 제13권1호
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• pp.37-47
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• 2024

This study presents the results of designing a system that determines the location of a person in an indoor environment based on a single IMU sensor attached to the tip of a person's shoe in an area where GPS signals are inaccessible. By adjusting for human footfall, it is possible to accurately determine human location and trajectory by correcting errors originating from the Inertial Measurement Unit (IMU) combined with advanced machine learning algorithms. Although there are various techniques to identify stepping, our study successfully recognized stepping with 98.7% accuracy using an artificial intelligence model known as Long Short-Term Memory (LSTM). Drawing upon the enhancements in our methodology, this article demonstrates a novel technique for generating a 200-meter trajectory, achieving a level of precision marked by a 2.1% error margin. Indoor pedestrian navigation systems, relying on inertial measurement units attached to the feet, have shown encouraging outcomes.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.149-156
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• 2003

This paper presents an underwater hybrid navigation system for a semi-autonomous underwater vehicle (SAUV). The navigation system consists of an inertial measurement unit (IMU), an ultra-short baseline (USBL) acoustic navigation sensor and a doppler velocity log (DVL) accompanying a magnetic compass. The errors of inertial measurement units increase with time due to the bias errors of gyros and accelerometers. A navigational system model is derived to include the error model of the USBL acoustic navigation sensor and the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 25 in the order. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors and correct the state equation when the measurements are available. Simulation was performed with the 6-d.o.f. equations of motion of SAUV in a lawn-mowing survey mode. The hybrid underwater navigation system shows good tracking performance by updating the error covariance and correcting the system's states with the measurement errors from a DVL, a magnetic compass and a depth senor. The error of the estimated position still slowly drifts in horizontal plane about 3.5m for 500 seconds, which could be eliminated with the help of additional USBL information.

• 한국항공우주학회지
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• 제50권9호
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• pp.617-625
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• 2022

본 논문은 사격 차선 정렬을 위하여 움직일 수 있는 교정 대상을 이용해 각속도계와 가속도계의 편차를 보상하는 방법을 다룬다. 교정 대상에 대한 정보는 영상 센서를 통해 획득하며 이를 이용해 발사장치에 부착된 관성측정 장치의 오차를 보정한다. 시뮬레이션을 통해 제안한 알고리즘의 성능을 검증하였으며, 특히 관성 좌표계에서 교정 대상에 대한 위치 정보를 정확하게 획득함으로써 발사장치의 관성 센서 편차를 효과적으로 보상할 수 있음을 보인다.

• ETRI Journal
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• 제42권1호
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• pp.46-53
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• 2020

Gait analysis is an effective clinical tool across a wide range of applications. Recently, inertial measurement units have been extensively utilized for gait analysis. Effective gait analyses require good estimates of heel-strike and toe-off events. Previous studies have focused on the effective device position and type of triaxis direction to detect gait events. This study proposes an effective heel-strike and toe-off detection algorithm using a smart insole with inertial measurement units. This method detects heel-strike and toe-off events through a time-frequency analysis by limiting the range. To assess its performance, gait data for seven healthy male subjects during walking and running were acquired. The proposed heel-strike and toe-off detection algorithm yielded the largest error of 0.03 seconds for running toe-off events, and an average of 0-0.01 seconds for other gait tests. Novel gait analyses could be conducted without suffering from space limitations because gait parameters such as the cadence, stance phase time, swing phase time, single-support time, and double-support time can all be estimated using the proposed heel-strike and toe-off detection algorithm.

• 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%.

• Safety and Health at Work
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• 제3권3호
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• pp.192-198
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• 2012

Objectives: Slip and fall accidents in the workplace are one of the top causes of work related fatalities and injuries. Previous studies have indicated that fall risk was related to postural and dynamic stability. However, the usage of this theoretical relationship was limited by laboratory based measuring instruments. The current study proposed a new method for stability assessment by use of inertial measurement units (IMUs). Methods: Accelerations at different body parts were recorded by the IMUs. Postural and local dynamic stability was assessed from these measures and compared with that computed from the traditional method. Results: The results demonstrated: 1) significant differences between fall prone and healthy groups in IMU assessed dynamic stability; and 2) better power of discrimination with multi stability index assessed by IMUs. Conclusion: The findings can be utilized in the design of a portable screening or monitoring tool for fall risk assessment in various industrial settings.

• 한국컴퓨터그래픽스학회논문지
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• 제19권4호
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• pp.13-22
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• 2013

모션 캡처 장치는 자연스러운 인체 동작을 생성하는 것을 용이하게 하여 영화, 컴퓨터 게임, 컴퓨터 애니메이션 등 여러 분야에서 폭넓게 사용되고 있다. 그 중 관성 센서를 활용한 모션 캡처 장치는 보다 널리 사용되고 있는 광학 모션 캡처 장비에 비해 소요 공간과 비용 측면에서 이점을 가지고 있으나 비교적 높은 노이즈로 인해 측정 결과의 정밀도가 떨어지는 단점이 있다. 특히 관성 센서에 포함되어 중력 방향을 계측하는 가속도 센서는 센서의 선형 가속 운동으로 인해 중력 방향의 계측 정밀도가 떨어지는 문제를 갖는다. 본 논문에서는 관절체에 부착된 센서의 자세 측정 정확도를 높이기 위해 가속도 센서에서 선형 가속도 성분을 제거하는 기법을 제안한다. 아울러 센서가 부착되어 있는 관절체의 회전축 및 센서의 부착 위치를 보정하는 기법을 소개한다. 이 보정 기법은 관성 센서가 관절체의 임의의 위치와 방향으로 부착되는 것을 가능하게 한다.

• 재활복지공학회논문지
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• 제9권2호
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• pp.161-168
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• 2015

본 논문은 자체 개발한 관성측정장치의 가속도, 각속도, 지자기계 데이터를 이용하여 보행거리를 측정하는 시스템 개발에 관한 것이다. 관성센서들의 오프셋 및 이득 오차를 최소화하기 위하여 9축의 자유도를 갖는 지그를 제작하였으며, 이를 이용하여 캘리브레이션을 수행하였다. 보행거리의 정확한 측정을 위하여, 기울기 하강법을 이용하여 가속도계의 중력성분 제거 및 보행패턴 분석을 통한 드리프트 성분을 제거하였다. 최종적으로 보정된 가속도 데이터의 이중적분을 통하여 보행거리를 측정하였다. 시스템의 성능 평가를 위하여, 실내 직선 10m 직선 보행에 대하여 캘리브레이션 전, 후 오차 개선 비율를 비교하였으며, 간단한 보행에 대해 Vicon과의 비교 실험을 수행하였다. 직선 보행에 대해서는 x, y, z축 각각에 대하여 $31.4{\pm}14.38%$(mean${\pm}$S.D.), $78.64{\pm}10.84%$ 및 $69.71{\pm}26.25%$ 개선이 되었음을 확인하였으며, Vicon과의 비교 실험 결과 x, y, z축 각각에 대하여 0.1m, 0.16m, 0.12m의 오차를 얻을 수 있었다.