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크랭크축의 미세속도변화를 이용한 선박엔진의 착화불량 상태 감시
강호현 ( Ho Hyeon Kang ),안중환 ( Jung Hwan Ahn ),김화영 ( Hwa Young Kim ) 한국센서학회 2022 센서학회지 Vol.31 No.1
In this study an efficient method for detecting and monitoring engine misfiring, focusing on minute speed changes in the crankshaft is proposed., Its validity is verified using various misfiring cases. Typically, the crankshaft speed fluctuates around the normal value depending on the engine misfiring status. Even a minute speed change in the crankshaft can be estimated by measuring the rotation time of each tooth of the 118-tooth flywheel attached to the crankshaft with a 2-MHz timer. Therefore, a speed pattern for an in-line six-cylinder engine consists of 236 tooth rotation speeds corresponding to the two rotations of the crankshaft, in which all the cylinders complete four-stroke cycle. FFT analysis can reduce the number of components of a speed pattern from 236 to just four major components: - fundamental frequency_(f), 2f, 3f, 6f., - This makes the comparison of the misfiring cases simpler and faster. In the experiment, five engine status cases (one normal firing and, four misfiring cases) were simulated. While the 6f component was the largest for the normal case, the f component increased as misfiring occurred one, two apart, and two consecutive times. The 3D FFT pattern comprising the ratio of f, 2f, and 3f, 6f showed that the distance between the misfiring and normal states was larger.
조난자 탐색을 위한 드론 네비게이션 시스템무인드론을 활용한 조난자 탐색
강호현(Ho Hyun Kang),권대현(Dae Hyeon Kwon),신수용(Soo Young Shin) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.11
본 논문은 산간 지역에 조난자가 발생하는 경우 무인 드론을 사용하여 의심 영역을 탐색(수색)하는 시스템을 제안한다. 드론이 조난자를 발견한 경우에 인근에 착륙하여 구조대가 도착할 때까지 버틸 수 있는 비상식량과 응급키트를 제공한다. 조난자 탐색을 위한 구역을 지정하고 그 구역으로 드론이 이동(네비게이션)한다. 장착된 카메라를 이용한 객체 감지 시스템을 통해 조난자를 탐색하여 조난자 근처에 드론으로 구호물자를 지급한다. 이후에는 계속해서 조난자를 탐색하도록 알고리즘을 지정한다. 무인 드론을 사용하여 제안하는 시스템을 구성하기 때문에 광범위한 영역을 동시에 여러 개를 사용하여 탐색하고 활용할 수 있다.
천동훈(Dong-Hun Cheon),이재욱(Jae-Wook Lee),우성현(Seong-Hyeon Woo),최지욱(Ji-Wook Choi),강호선(Ho-Sun Kang),이장명(Jang-Myung Lee) 제어로봇시스템학회 2021 제어·로봇·시스템학회 논문지 Vol.27 No.3
In this paper, we propose an adaptive four-leg landing system for a quadcopter to enable stable landing on inclined surfaces or rough terrain while maintaining its attitude. A rotorcraft has a disadvantage in that it must have a flat ground for landing because the existing landing gear system is fixed and cannot be changed according to ground conditions. The proposed adaptive landing system makes it possible for a quadcopter to operate in various environments with minimal sensors. For this purpose, a four-leg landing system with two degrees of freedom having a two-link structure was manufactured. Through kinematic analysis of the landing leg, the coordinates of the joint and end-effector were identified, and an equation for horizontal control was established. When landing on the slope, the ground surface was detected using force sensors, attached at the end of each leg. Adaptive landing control was performed according to the roll and pitch values of the inertial measurement unit sensor mounted on the quadcopter. The proposed system was pre-validated in the simulation environment of Matlab Simulink. The superiority of the proposed system was verified experimentally in various environments. In an indoor environment, the effectiveness of the system was verified in a situation where it landed at a constant speed using a testbed. Finally, the system stability was verified through flying and landing of the quadcopter in an outdoor environment.