관성센서 기반 보행 분석 시스템 구현

조재성(J. S. Cho),강신일(S. I. Kang),이기혁(K. H. Lee),장성호(S. H. Jang),김인영(I. Y. Kim),이종실(J. S. Lee) 한국재활복지공학회 2015 재활복지공학회논문지 Vol.9 No.2

본 논문은 하지의 움직임을 측정하고 분석할 수 있는 관성센서 기반 보행분석 시스템에 관한 것이다. 본 시스템 구현을 위해 자이로스코프, 가속도계 및 지자계 신호를 이용한 자세·방위 측정장치 모듈을 일체형으로 개발하였으며, 다수의 모듈을 환자의 분절에 부착하여 공간상에서 각 분절의 방위각을 제공할 수 있도록 하였다. 또한 재활과 관련된 많은 응용에 있어 중요한 생체역학 측정값인 신체 분절간의 관절각을 추출하는 알고리즘을 제안하였다. 개발한 자세·방위 측정장치 모듈의 성능을 평가하기 위하여 3차원 공간상의 변위 및 방위를 밀리미터 해상도로 제공할 수 있는 Vicon을 참조 측정 시스템으로 이용하였으며, yaw와 pitch에서 1.08, 1.72도의 평균 제곱근 오차를 얻을 수 있었다. 보행 분석 시스템의 성능 검증을 위하여 7개의 AHRS 모듈을 하지에 부착하고 고관절, 무릎, 발목에 대한 관절각을 계산하여, Vicon과의 비교 실험을 수행하였다. 실험 결과 본 연구에서 개발한 시스템은 뇌졸중 후 회복단계 동안 사지 및 보행 동작을 실시간으로 분석, 제공함으로서 재활의 효과, 난이도 조절 및 피드백 요소를 제공할 수 있을 것으로 판단된다. In this paper, we present an inertial sensor-based gait analysis system to measure and analyze lower-limb movements. We developed an integral AHRS(Attitude Heading Reference System) using a combination of rate gyroscope, accelerometer and magnetometer sensor signals. Several AHRS modules mounted on segments of the patient’s body provide the quaternions representing the patient segments’s orientation in space. And a method is also proposed for calculating three-dimensional inter-segment joint angle which is an important bio-mechanical measure for a variety of applications related to rehabilitation. To evaluate the performance of our AHRS module, the Vicon motion capture system, which offers millimeter resolution of 3D spatial displacements and orientations, is used as a reference. The evaluation resulted in a RMSE(Root Mean Square Error) of 1.08 and 1.72 degree in yaw and pitch angle. In order to evaluate the performance of our the gait analysis system, we compared the joint angle for the hip, knee and ankle with those provided by Vicon system. The result shows that our system will provide an in-depth insight into the effectiveness, appropriate level of care, and feedback of the rehabilitation process by performing real-time limb or gait analysis during the post-stroke recovery.

퍼지추론을 이용한 무인잠수정의 하이브리드 항법 시스템

이판묵(Pan-Mook Lee),이종무(Chong-Moo Lee),정성욱(Seong-Wook Cheong) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.3

This paper presents a hybrid navigation system for AUV to locate its position precisely in rough sea. The tracking system is composed of various sensors such as an inclinometer, a tri-axis magnetometer, a flow meter, and a super short baseline(SSBL) acoustic position tracking system. Due to the inaccuracy of the attitude sensors, the heading sensor and the flowmeter, the predicted position slowly drifts and the estimation error of position becomes larger. On the other hand, the measured position is liable to change abruptly due to the corrupted data of the SSBL system in the case of low signal to noise ratio or large ship motions. By introducing a sensor fusion technique with the position data of the SSBL system and those of the attitude heading flowmeter reference system (AHFRS), the hybrid navigation system updates the three-dimensional position robustly. A Kalman filter algorithm is derived on the basis of the error models for the flowmeter dynamics with the use of the external measurement from the SSBL. A failure detection algorithm decides the confidence degree of external measurement signals by using a fuzzy inference. Simulation is included to demonstrate the validity of the hybrid navigation system.

다용도 실시간 경사각과 방위각 연속 측정 시스템 개발연구

김규현,조성호,정현기,이효선,손정술 한국지구과학회 2013 한국지구과학회지 Vol.34 No.6

In geophysics and geophysical exploration fields, we can use information about inclination and azimuth in various ways. These include borehole deviation logging for inversion process, real-time data acquisition system, geophysical monitoring system, and so on. This type of information is also necessarily used in the directional drilling of shale gas fields. We thus need to develop a subminiature, low-powered, multi-functional inclination and azimuth measurement system for geophysical exploration fields. In this paper, to develop real-time measurement system, we adopt the high performance low power Micro Control Unit (made with state-of-the-art Complementary Metal Oxide Semiconductor technology) and newly released Micro Electro Mechanical Systems Attitude Heading Reference System sensors. We present test results on the development of a multifunctional real-time inclination and azimuth measurement system. The developed system has an ultra-slim body so as to be installed in 42mm sonde. Also, this system allows us to acquire data in real-time and to easily expand its application by synchronizing with a depth encoder or Differential Global Positioning System. 최근 지구물리·물리탐사 분야에서 경사각과 방위각 정보는 시추공 물리검층 및 물리탐사 자료보정을 위한 시추공 편차검층, 이동형 실시간 자료획득 시스템, 기타 지구물리 모니터링 시스템 등 다양하게 활용되면서 그 중요성이 높아지고 있다. 특히 최근 셰일가스의 개발이 가능하게 한 방향시추 기술에서도 경사각과 방위각 정보는 필수일 정도로그 응용범위가 매우 넓다. 따라서 여러 분야에 응용될 수 있는 경사각과 방위각 측정 시스템의 초소형 옥외 저전력 운용이 절실해졌다. 본 논문에서는 최신 CMOS 저전력, 고성능 MCU 및 멤스(MEMS) 자세방위기준장치(AHRS)를 도입하여 초소형, 저전력으로 제작된 다용도 야외시험용 실시간 경사각과 방위각 연속 측정 시스템 개발 연구의 결과를 제시하고자 한다. 시스템은 최소 지름 42 mm의 존데 내에 설치될 수 있도록 초슬림 형태로 제작되었으며 실시간 데이터획득이 가능할 뿐만 아니라 엔코더, DGPS 연동으로 운용 확장이 가능하여 다양한 응용이 기대된다.

실시간 시추공 차분자기/편차 검층 시스템 개발 및 기초 현장시험

조성호,정현기,이효선,김예솔 한국자원공학회 2019 한국자원공학회지 Vol.56 No.1

A smart device-based borehole deviation and magnetic gradient logging system is proposed. The whole system consists of a sonde, 500-m long electric winch module, rotary encoder module, the main control module, and a smart device. The sonde is made up of an attitude-and-heading-references-system based on digital output miniature high-precision microelectromechanical systems, a magnetic gradiometer sensor composed of two separated three-axis fluxgate sensors spaced 500 mm apart with analog voltage output, and a 24-bit analog-to-digital high-resolution acquisition/control module. The three component modules are situated in 1.5-m length 48-mm diameter titanium housing. To evaluate the performance of the system, preliminary field test was performed at 440-m borehole located in Ulsan samjeongri. The falling speed of sonde was 0.3 m/s and 2-Hz continuous measurement and monitoring were carried out. 최신 전자, 정보통신 기술을 활용하여 실시간 차분자기/편차 검층 시스템을 개발하였다. 전체 시스템은 존데, 500 m 전동윈치 모듈, 로터리 엔코더 모듈, 주 제어모듈과 스마트 디바이스로 구성된다. 존데는 길이 1.5 m 외경 48 mm 티타늄 하우징을 가지며 내부에 디지털 출력 초소형 고정밀 MEMS 기반 AHRS, 두 개의 3축 플럭스케이트 센서가 500 mm 이격되어 있는 아날로그 고정밀 차분 자기센서, 24 비트 analog-to-digital 고정밀 계측/제어 모듈이 포함된다. 개발된 시스템의 기초현장시험을 위해 울산 삼정리 반정 저수지 옆 440 m 시추공에서 0.3 m/s의 속도로 존데를 하강시키면서 2 Hz 연속측정을 수행하였다.

칼만 필터 기반의 측정 공분산 값을 이용한 최적 자세 추정

김종명,이현재,김영욱 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.11

본 논문은 자세 및 방향 결정시스템(AHRS)의 성능을 향상시키기 위한 새로운 기법인 순차적 측정 공분산(Sequential Measurement Norm Covariance)을 제시하였다. 순차적 측정 공분산 기법은 현재 측정값을 포함하고 과거 N개의 데이터를 순차적으로 활용하여 측정 공분산 값을 업데이트하는 기법이다. 이 방법으로 저가의 센서를 사용할 때 가장 큰 문제점인 고기동이나 외란이 심할 경우 자세결정 성능이 현저히 감소하는 것을 최소화 시켰다. 즉, 본 논문에서는 SMNC을 활용하여 기존의 알고리즘 등이 고기동이나 외란이 심한 경우에 성능을 제대로 발휘하지 못하는 단점을 극복하는 새로운 기법을 제시하였으며, 수치 시뮬레이션을 통해 알고리즘의 검증을 완료하였다. This paper propose SMNC(Sequential Measurement Norm Covariance) that is improvement of efficiency of AHRS(Attitude&Heading Reference System). SMNC updates measurement error covariance using current measurement and N number of past data. This method can minimize problem of low-cost sensors that the performance reduction caused disturbance. In this paper a new technique to minimize sensor noise caused disturbance is developed, and algorithm is verified using the numerical simulation.

규칙기반 필터 및 기계학습을 이용한 AHRS용 자세추정 알고리즘 고찰

이창준,이정근 제어·로봇·시스템학회 2024 제어·로봇·시스템학회 논문지 Vol.30 No.5

Accurate orientation estimation is important in various applications such as robotics, unmanned vehicles, and biomechanics, in which an attitude and heading reference system (AHRS) is essential. The AHRS provides orientation by processing signals from an inertial measurement unit (IMU) consisting of a gyroscope, an accelerometer, and a magnetometer. Numerous rule-based filtering algorithms have been developed to estimate orientation based on IMU signals. However, several studies have recently been conducted to develop machine-learning-based algorithms. In this study, the methodology and estimation performance of IMU-based orientation estimation algorithms were reviewed by using rule-based filtering and machine learning approaches. A total of 37 papers were selected after searching the databases of IEEE Xplore, PubMed, ScienceDirect, and Google Scholar. Rule-based filtering algorithms were divided into Kalman and complementary filters depending on the weight calculation process. Approaches were also categorized into the direct estimation of the orientation and the correction of the error terms in the orientation or angular velocity. The machine learning algorithms were divided into the following: a combined method that estimated or corrected orientation by combining machine learning model with a rule-based filtering algorithm; and an end-to-end method that directly estimated orientation through the model. Results showed that although the machine learning algorithms could reliably perform attitude estimation, the rule-based filtering algorithms still demonstrated superior performance in the estimation of 3D orientation, including attitude and heading.

Vibration-Robust Attitude and Heading Reference System Using Windowed Measurement Error Covariance

Jong-Myeong Kim,Sung-Hoon Mok,Henzeh Leeghim,Chang-Yull Lee 한국항공우주학회 2017 International Journal of Aeronautical and Space Sc Vol.18 No.3

In this paper, a new technique for attitude and heading reference system (AHRS) using low-cost MEMS sensors of the gyroscope, accelerometer, and magnetometer is addressed particularly in vibration environments. The motion of MEMS sensors interact with the scale factor and cross-coupling errors to produce random errors by the harsh environment. A new adaptive attitude estimation algorithm based on the Kalman filter is developed to overcome these undesirable side effects by analyzing windowed measurement error covariance. The key idea is that performance degradation of accelerometers, for example, due to linear vibrations can be reduced by the proposed measurement error covariance analysis. The computed error covariance is utilized to the measurement covariance of Kalman filters adaptively. Finally, the proposed approach is verified by using numerical simulations and experiments in an acceleration phase and/or vibrating environments.

A Study on Attitude Heading Reference System Based Micro Machined Electro Mechanical System for Small Military Unmanned Underwater Vehicle

Hwang, A-Rom,Yoon, Seon-Il The Korean Society of Marine Engineering 2015 한국마린엔지니어링학회지 Vol.39 No.5

Generally, underwater unmanned vehicle have adopted an inertial navigation system (INS), dead reckoning (DR), acoustic navigation and geophysical navigation techniques as the navigation method because GPS does not work in deep underwater environment. Even if the tactical inertial sensor can provide very detail measurement during long operation time, it is not suitable to use the tactical inertial sensor for small size and low cost UUV because the tactical inertial sensor is expensive and large. One alternative to INS is attitude heading reference system (AHRS) with the micro-machined electro mechanical system (MEMS) inertial sensor because of MEMS inertial sensor's small size and low power requirement. A cost effective and small size attitude heading reference system (AHRS) which incorporates measurements from 3-axis micro-machined electro mechanical system (MEMS) gyroscopes, accelerometers, and 3-axis magnetometers has been developed to provide a complete attitude solution for UUV. The AHRS based MEMS overcome many problems that have inhibited the adoption of inertial system for small UUV such as cost, size and power consumption. Several evaluation experiments were carried out for the validation of the developed AHRS's function and these experiments results are presented. Experiments results prove the fact that the developed MEMS AHRS satisfied the required specification.

A Study on Attitude Heading Reference System Based Micro Machined Electro Mechanical System for Small Military Unmanned Underwater Vehicle

황아롬,윤선일 한국마린엔지니어링학회 2015 한국마린엔지니어링학회지 Vol.39 No.5

Generally, underwater unmanned vehicle have adopted an inertial navigation system (INS), dead reckoning (DR), acoustic navigation and geophysical navigation techniques as the navigation method because GPS does not work in deep underwater environment. Even if the tactical inertial sensor can provide very detail measurement during long operation time, it is not suitable to use the tactical inertial sensor for small size and low cost UUV because the tactical inertial sensor is expensive and large. One alternative to INS is attitude heading reference system (AHRS) with the micro-machined electro mechanical system (MEMS) inertial sensor because of MEMS inertial sensor's small size and low power requirement. A cost effective and small size attitude heading reference system (AHRS) which incorporates measurements from 3-axis micro-machined electro mechanical system (MEMS) gyroscopes, accelerometers, and 3-axis magnetometers has been developed to provide a complete attitude solution for UUV. The AHRS based MEMS overcome many problems that have inhibited the adoption of inertial system for small UUV such as cost, size and power consumption. Several evaluation experiments were carried out for the validation of the developed AHRS's function and these experiments results are presented. Experiments results prove the fact that the developed MEMS AHRS satisfied the required specification.

수중 운동체의 자세 추정을 위한 가속도계 측정치 외란 제거 기법

강철우,박찬국 한국항공우주학회 2011 한국항공우주학회 학술발표회 논문집 Vol.2011 No.11

본 논문에서는 일정한 전진 속도를 지닌 수중 운동체의 자세제어를 위한 자세 계산 알고리즘을 제안한다. 가속도계와 지자기계를 이용한 자세 계산 알고리즘은 항체의 회전에 의해 발생하는 가속도에 의해 자세오차가 발생한다. 이를 제거하기 위해 전진 방향 속도와 자이로에서 측정되는 각속도를 이용해 원심력 성분을 계산하여 외란 성분을 계산한다. 외란이 제거된 가속도 신호를 이용하여 자세 추정을 수행하면 기존의 자세 추정 방식보다 정밀한 자세 추정 결과를 얻을 수 있다. In this paper, improved attitude estimation is proposed for underwater vehicle which maneuvers with constant velocity. the attitude estimation which uses vector measurement of accelerometer and magnetometer is affected by acceleration from rotational maneuvers. To compensate the acceleration disturbance, the proposed method calculate the centrifugal acceleration using angular rate and body velocity. The attitude estimation result is improved by sing the accelerometer signal without disturbance as a measurement.