Evaluating LIMU System Quality with Interval Evidence and Input Uncertainty

Xiangyi Zhou,Zhi-Jie Zhou,Xiaoxia Han,Zhichao Ming,Yanshan Bian 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.11

The laser inertial measurement unit is a precision device widely used in rocket navigation system and other equipment, and its quality is directly related to navigation accuracy. In the quality evaluation of laser inertial measurement unit, there is inevitably uncertainty in the index input information. First, the input numerical information is in interval form. Second, the index input grade and the quality evaluation result grade are given according to different national standards. So, it is a key step to transform the interval information input by the index into the data form consistent with the evaluation result grade. In the case of uncertain input, this paper puts forward a method based on probability distribution to solve the problem of asymmetry between the reference grade given by the index and the evaluation result grade when evaluating the quality of laser inertial measurement unit. By mapping the numerical relationship between the designated reference level and the evaluation reference level of the index information under different distributions, the index evidence symmetrical with the evaluation reference level is given. After the uncertain input information is transformed into evidence of interval degree distribution by this method, the information fusion of interval degree distribution evidence is carried out by interval evidential reasoning algorithm, and the evaluation result is obtained by projection covariance matrix adaptive evolution strategy optimization. Taking a five-meter redundant laser inertial measurement unit as an example, the applicability and effectiveness of this method are verified.

Automatic wall slant angle map generation using 3D point clouds

Kim, Jeongyun,Yun, Seungsang,Jung, Minwoo,Kim, Ayoung,Cho, Younggun Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.4

Recently, quantitative and repetitive inspections of the old urban area were conducted because many structures exceed their designed lifetime. The health of a building can be validated from the condition of the outer wall, while the slant angle of the wall widely serves as an indicator of urban regeneration projects. Mostly, the inspector directly measures the inclination of the wall or partially uses 3D point measurements using a static light detection and ranging (LiDAR). These approaches are costly, time-consuming, and only limited space can be measured. Therefore, we propose a mobile mapping system and automatic slant map generation algorithm, configured to capture urban environments online. Additionally, we use the LiDAR-inertial mapping algorithm to construct raw point clouds with gravity information. The proposed method extracts walls from raw point clouds and measures the slant angle of walls accurately. The generated slant angle map is evaluated in indoor and outdoor environments, and the accuracy is compared with real tiltmeter measurements.

Multiple IMU sensor fusion using resolution refinement method to reduce quantization error

유성식,Humayun Kabir,이흥식 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

We propose a sensor fusion method of multiple inertial measurement units (IMU) with different resolutions to reduce quantization errors and improve the measurement accuracy of dead reckoning navigation. The resolution and dynamic range of the accelerometer within MEMS IMU have a trade-off relationship; the selection of a fixed dynamic range in a single IMU may increase the error of the inertial navigation system. We integrate multiple accelerometer signals with different resolutions into a weighted average that depends on the measurements. This reduces the quantization error by creating an optimal resolution tailored to the specific measurement range. To verify the proposed algorithm, we examined the effect of mathematically generated accelerometer values.

표면 근전도와 관성측정장비를 이용한 손동작 분류 시스템 개발

이효찬(H.-C. Lee),최석규(S.-G. Choi),김근우(G.-W. Kim),류강현(G.-H. Ryu),김성욱(S.-U. Kim),황한정(H.-J. Hwang) 한국정보기술학회 2020 Proceedings of KIIT Conference Vol.2020 No.10

본 연구의 목표는 표면 근전도(surface electromyography: sEMG)와 관성측정장비(inertial measurement unit: IMU)를 함께 사용하여 다양한 손동작을 높은 성능으로 분류하는 것이다. 10명의 피험자가 실험에 참여하였으며, 실험을 진행하는 동안 손등에 부착한 sEMG와 IMU센서를 이용하여 데이터를 수집하였다. 오프라인 실험에서 피험자들은 9가지의 서로 다른 손동작 과제를 각각 2초씩 총 20회 반복 수행하였다. 측정된 sEMG와 IMU데이터로부터 손동작 움직임을 분류하기 위한 특징을 추출하였으며, 5x5-fold 교차 검증과 선형분류판별기를 활용하여 분류정확도를 계산하였다. 오프라인 실험 데이터를 활용하여 분류기를 생성한 후, 실시간으로 9가지 손동작을 구분하는 온라인 실험을 별도로 수행하였으며, 각각의 손동작을 10회씩 수행하여 실시간 분류 정확도를 산출하였다. sEMG와 IMU특징을 함께 사용하였을 때 오프라인 평균 분류정확도는 95.19 ± 2.07%, 온라인 평균 분류정확도는 81.78 ± 11.10%로 sEMG와 IMU를 개별적으로 사용한 정확도 대비 유의미하게 높은 것을 확인하였다. 본 연구에서는 sEMG와 IMU를 동시에 사용하여 사용자의 여러 손동작을 높은 정확도로 구분할 수 있음을 확인하였으며, 다양한 인간-컴퓨터 인터페이스 기술로 유용하게 활용될 수 있을 것으로 기대된다. The objective of this study was to classify different hand motions with high performance using surface electromyography (sEMG) and inertial measurement unit (IMU) data. Ten subjects participated in this study, during which sEMG and IMU data were measured on the back of the hand. In the offline experiment, each subject repeatedly performed nine different hand motions 20times for 2s each. sEMG and IMU features were extracted to classify the nine hand motions, and a classification accuracy was estimated using a linear discriminant analysis and 5×5 fold cross-validation. Using a classifier constructed using the offline sEMG and IMU features, the online experiment was additionally performed to classify the nine different hand motions in real time, where an online classification accuracy was estimated for each hand motion performed 10times. As a result, an offline and online classification accuracy of 95.19 ± 2.07% and 81.78 ± 11.10% were obtained when using a combination of sEMG and IMU features, which were statistically higher than those obtained using sEMG and IMU independently. In this study, we confirmed that different hand motions can be discriminated with high performance when using sEMG and IMU features simultaneosly, and it is expected that this result can be usefully used to develop human-computer interface applications.

무선 보행 분석을 위한 블루투스 기반 관성 측정 장치의 활용 타당성 분석

황소리,성주환,박희수,한성민,윤인찬 대한의용생체공학회 2020 의공학회지 Vol.41 No.3

The purpose of this paper is to review the validation on the application of low frequency IMU(Inertial Measurement Unit) sensors by replacing high frequency motion analysis systems. Using an infrared-based 3D motion analysis system and IMU sensors (22 Hz) simultaneously, the gait cycle and knee flexion angle were measured. And the accuracy of each gait parameter was compared according to the statistical analysis method. The Bland-Altman plot analysis method was used to verify whether proper accuracy can be obtained when extracting gait parameters with low frequency sensors. As a result of the study, the use of the new gait assessment system was able to identify adequate accuracy in the measurement of cadence and stance phase. In addition, if the number of gait cycles is increased and the results of body anthropometric measurements are reflected in the gait analysis algorithm, is expected to improve accuracy in step length, walking speed, and range of motion measurements. The suggested gait assessment system is expected to make gait analysis more convenient. Furthermore, it will provide patients more accurate assessment and customized rehabilitation program through the quantitative data driven results.

Evaluation of Validity and Reliability of Inertial Measurement Unit-Based Gait Analysis Systems

조영신,장성호,조재성,김미정,이혁동,이성영,문상복 대한재활의학회 2018 Annals of Rehabilitation Medicine Vol.42 No.6

Objective To replace camera-based three-dimensional motion analyzers which are widely used to analyze body movements and gait but are also costly and require a large dedicated space, this study evaluates the validity and reliability of inertial measurement unit (IMU)-based systems by analyzing their spatio-temporal and kinematic measurement parameters. Methods The investigation was conducted in three separate hospitals with three healthy participants. IMUs were attached to the abdomen as well as the thigh, shank, and foot of both legs of each participant. Each participant then completed a 10-m gait course 10 times. During each gait cycle, the hips, knees, and ankle joints were observed from the sagittal, frontal, and transverse planes. The experiments were conducted with both a camerabased system and an IMU-based system. The measured gait analysis data were evaluated for validity and reliability using root mean square error (RMSE) and intraclass correlation coefficient (ICC) analyses. Results The differences between the RMSE values of the two systems determined through kinematic parameters ranged from a minimum of 1.83 to a maximum of 3.98 with a tolerance close to 1%. The results of this study also confirmed the reliability of the IMU-based system, and all of the variables showed a statistically high ICC. Conclusion These results confirmed that IMU-based systems can reliably replace camera-based systems for clinical body motion and gait analyses.

Digital Goniometer for Measuring 3-Dimensional Neck Movement: Reliability and Validity Test

정도영,김현수,김동욱,한지원 KEMA학회 2020 근골격계과학기술학회 Vol.4 No.1

Background: In clinical setting, the cervical range of motion (ROM) is commonly used to identify movement impairment and assess function of neck. For assessing and improving the cervical ROM and proprioception, we developed the device using the digital goniometer with inertial measurement unit. Purpose: The purpose of this study was to determine the intra-rater reliability and validity of cervical ROM measurement using the digital goniometer and Cervcial Range-of-Motion (CROM) device. Study design: Cross-sectional study. Methods: Fifteen healthy subjects without neck pain were participated in this study. The measure-ments of flexion, extension, side-bending (right/left), and rotation (right/left) were made with CROM device and digital goniometer in sitting. Two trials of cervical ROM measurement (6 movements) were performed for each subject. Validity and intra-rater reliability were determined using Spearman correlation coefficient and intra-class correlation coefficient (ICC3,1) for digital goniometer and CROM, respectively. Results: The digital goniometer demonstrated good (Spearman ρ=0.88–0.98, p<0.01) validity for CROM. The intra-rater reliability was demonstrated for cervical flexion (ICC3,1=0.99), extension (ICC3,1=0.99), right (ICC3,1=0.99) and left (ICC3,1=0.99) lateral flexion, right (ICC3,1=0.99) and left (ICC3,1=0.99) rotation. Conclusions: The digital goniometer was found to be reliable and valid for measuring cervical ROM in three planes for normal subjects. However, before using the digital goniometer as an outcome measure in clinical settings, studies should be performed on subjects with neck pain.

두개의 초음파 거리계를 이용한 관성센서 기반의 의사 장기선 (Pseudo-LBL) 복합항법 알고리듬

이판묵(PAN-MOOK LEE),전봉환(BONG-HUAN JUN),홍석원(SEOK-WON HONG),임용곤(YONG-KON LIM),양승일(SEUNG-IL YANG) 한국해양공학회 2005 韓國海洋工學會誌 Vol.19 No.5

This paper presents an integrated underwater navigational algorithm for unmanned underwater vehicles, using additional two-range transducers. This paper proposes a measurement model, using two range measurements, to improve the performance of an IMU-DVL (inertial measurement unit - Doppler velocity log) navigation system for long-time operation of underwater vehicles, excluding DVL measurement. Extended Kalman filter was adopted to propagate the error covariance, to update the measurement errors, and to correct the state equation when the external measurements are available. Simulation was conducted with the 6-d.o.f. nonlinear numerical model of an AUV in lawn-mowing survey mode, at current flow, where the velocity information is unavailable. Simulations illustrate the effectiveness of the integrated navigation system, assisted by the additional range measurements without DVL sensing.

Transfer Alignment Design Using a Gyro-free Inertial Navigation System

Jae Hoon Son,Dong-Hwan Hwang,Sang Heon Oh 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.10

The initial value of the inertial navigation system of a launched vehicle can be obtained through the transfer alighnment. If the rotational rate of a moving vehicle exceeds the range of the gyroscope measurements, the angular velocity cannot be measured. Use of the gyroscope with complex structure, large size, more power consumption, and high cost may be avoided. These problems can be resolved by adopting a gyro-free inertial navigation system (GF-INS), which comprises only accelerometers. In the transfer alignment, the slave INS can be configured using a GF-INS. This paper proposes a new type of GF-INS-based transfer alignment design. The configuration of the proposed transfer alignment is presented and an error model of the GF-INS for the Kalman filter is derived. The observability of the proposed method is investigated for a gyro-free inertial measurement unit (GF-IMU) with a cubic structure at level flight with constant velocity and turn maneuver motions. Employing the same GF-IMU undergoing the same motions, the performance of the proposed transfer alignment is also evaluated. As the angular velocity can be measured additionally to the velocity and attitude, angular velocity matchings are also considered in the observability analysis and performance evaluation. It is found that the velocity and attitude measurements should be combined in the matchings of the GF-INS to improve the accuracy of the state estimates.

Integration of soft computational simulator and strapdown inertial navigation system for aerial surveying project planning

Ahmed. Serwa,Hossam H. El-Semary 대한공간정보학회 2016 Spatial Information Research Vol.24 No.3

Aerial photogrammetry is an engineering sur- veying operation, which is a traditional methodology that can be used to map the earth. The rapid development in instrumentation and computer dependency led to the need to develop photogrammetric software. Inertial navigation system (INS) can provide light weight positioning methodology in aerial imagery. This research is a trial to integrate INS with a pre-developed soft computational simulator of 3A3P in order to obtain a dynamic virtual map. The developed system supports inertial measurement unit (IMU) and link the theoretical exposure station coor- dinates and the inertial measurements. The developed system enables photogrammetrists to visualize the aerial imaging process and it can be used to monitor the imaging process. It makes all the calculations that are required to obtain the theoretical coordinates and produces a virtual aerial map. The system converts the measurements of the IMU into space coordinates that can be useful to monitor the imaging process.