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Wonkeun Youn,고하윤,Hyungsik Choi,Inho Choi,Joong-Hwan Baek,Hyun Myung 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2
This paper proposes a novel complete navigation system for autonomous flight of small unmanned aerial vehicles (UAVs) in GPS-denied environments. The hardware platform used to test the proposed algorithm is a small, custom-built UAV platform equipped with an onboard computer, RGB-D camera, 2D light detection and ranging (LiDAR), and altimeter. The error-state Kalman filter (ESKF) based on the dynamic model for low-cost IMU-driven systems is proposed, and visual odometry from the RGB-D camera and height measurement from the altimeter are fed into the measurement update process of the ESKF. The pose output of the ESKF is then integrated into the open-source simultaneous location and mapping (SLAM) algorithm for pose-graph optimization and loop closing. In addition, the computationally efficient collision-free path planning algorithm is proposed and verified through simulations. The software modules run onboard in real time with limited onboard computational capability. The indoor flight experiment demonstrates that the proposed system for small UAVs with low-cost devices can navigate without collision in fully autonomous missions while establishing accurate surrounding maps.
Development of a Compact-size and Wireless Surface EMG Measurement System
Wonkeun Youn,Jung Kim 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper proposes a compact-size and a wireless surface EMG(electromyography) measurement system of a noninvasive type. The limitations of the current EMG sensor system include its large size , and the necessity of a wire. Therefore, this study focused on the development of a compact size preamplifier and wireless EMG measurement system. The EMG described herein is comprised of a preamplifier including an electrode for the measurement of the EMG signal, a main amplifier for signal processing, DSP(digital signal processor) processor for A/D conversion and digital signal processing, and a Bluetooth module for wireless communication. EMG signal obtained by the developed system results in better signal-to-noise ratio (SNR) compared to commercially available EMG system. This SNR of the developed system can be attributed to repeated signal processing on analog circuit and DSP, which reduces the size of the developed system. In our power spectral density, the EMG signal was distributed between approximately 20Hz and 400Hz. A Compact size and wireless surface EMG measurement system with high SNR can be useful for providing subjects comfort and consequently controlling external prosthesis.
인간-기계 인터페이스를 위한 근육 진동 신호 기반 팔꿈치 굽힘 힘 예측
윤원근(Wonkeun Youn),김정(Jung Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The mechaomyography (MMG) is generated by the muscle surface oscillations due to pressure waves originating from the lateral expansion of the contracting muscle fibers. Since MMG signals reflect important aspect of muscle activities including the number and firing rates of recruited motor units (MUs). MMG signals could be utilized for predicting the exerted force by skeletal muscles. The objectives of this study were to investigate the feasibility of predicting isometric force from MMG signals and to explore the effect of muscle fatigue in performance of the force prediction. MMG signals from three contributed muscles during isometric elbow flexion were recorded as well as the force at wrist. Artificial neural network (ANN) with muscle fatigue compensation model were constructed and trained using the MMG signals collected for each subject, It was found that the isometric elbow flexion force could be accurately predicted by proposed methods, based on the values of normalized root mean square error (NRMSE) and the correlation coefficient (CC), with the performance of the ANN with fatigue compensation model being significantly better (NRMSE = 0.106±0.049, CC= 0.918±0.083) that those of its ANN (NRMSE = 0.160±0.045, CC= 0.710±0.211).
항공용 소프트웨어 개발 모델 및 테스팅 설계 기법에 관한 연구
윤원근,이백준,진영권,Youn, Wonkeun,Yi, Baeckjun,Jin, Youngkwon 항공우주시스템공학회 2013 항공우주시스템공학회지 Vol.7 No.3
The paper presents the comprehensive studies of ISTQB(International Software Testing Qualification Board) for the reliable software development system in term of various aspects. It is critical to understand how the software testing is achieved is to efficiently manage the development process, to reduce the development cost, and to ultimately ensure the safety of the entire software system. This study may provide an enriched understanding about the rationale and true intent the behind software development model and testing design methods of ISTQB on software developer, test analysts, test engineers. In addition, this paper may serve as a useful supplementary material for the avionic engineers to establish the new regulations in avionic industries.