• 한국정보기술학회 영문논문지
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• 제8권2호
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• pp.101-110
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• 2018

This paper introduces feedback linearization (FL) based adaptive sliding mode control (ASMC) effective against ground effects of the quadrotor UAV. The proposed control has the capability of estimation and effective rejection of those effects by adaptive mechanism, which resulting stable attitude and positioning of the quadrotor. As output variables of quadrotor, x-y-z position and yaw angle are chosen. Dynamic extension of the quadrotor dynamics is obtained for terms of roll and pitch control input to be appeared explicitly in x-y-z dynamics, and then linear feedback control including a ground effect is designed. A sliding mode control (SMC) is designed with a class of FL including higher derivative terms, sliding surfaces for which is designed as a class of integral type of resulting closed loop dynamics. The asymptotic stability of the overall system was assured, based on Lyapunov stability methods. It was evaluated through some simulation that attitude control capability is stable under excessive estimation error for unknown ground effect and initial attitude of roll, pitch, and yaw angle of $30^{\circ}$ in all. Effectiveness of the proposed method was shown for quadrotor system with ground effects.

• 자동차안전학회지
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• 제16권1호
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• pp.12-20
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• 2024

Side impact with MDB (moving deformable barrier) is common in side crash test protocols around the globe, most of which are quite similar to that of US NCAP side impact protocol but IIHS side impact protocol is considered to be the most harsh one due to the MDB's weight and impact speed. In this study US NCAP side impact and IIHS side impact test conditions are compared with respect to delta-V (impulse of the test vehicle), roll speed, and yaw speed as well as survival space (the smallest distance between the front driver seat cushion center to B pillar after the test). Error factors (friction between tire and ground, tolerance of vertical and longitudinal position of the MDB with respect to the test vehicle), which are resident in the test protocol is studied with respect to the global vehicle behavior (delta-V, roll, yaw) as well as survival space.

• 한국정밀공학회지
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• 제23권6호
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• pp.96-103
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• 2006

To establish of standard technique of nano-length measurement in 2D plane, new AFM system has been designed. In the long range (about several tens of ${\mu}m$), measurement uncertainty is dominantly affected by the Abbe error of XY scanning stage. No linear stage is perfectly straight; in other words, every scanning stage is subject to tilting, pitch and yaw motion. In this paper, an AFM system with minimum offset of XY sensing is designed. And XY scanning stage is designed to minimize rotation angle because Abbe errors occur through the multiply of offset and rotation angle. To minimize the rotation angle optimal design has performed by maximizing the stiffness ratio of motion direction to the parasitic motion direction of each stage. This paper describes the design scheme of full AFM system, especially about XY stage. Full range of fabricated XY scanner is $100{\mu}m\times100{\mu}m$. And tilting, pitch and yaw motion are measured by autocollimator to evaluate the performance of XY stage. As a result, XY scanner can have good performance. Using this AFM system, 3um pitch specimen was measured. The uncertainty of total system has been evaluated. X and Y direction performance is different. X-direction measuring performance is better. So to evaluate only ID pitch length, X-direction scanning is preferable. Its expanded uncertainty(k=2) is $\sqrt{(3.96)^2+(4.10\times10^{-5}{\times}p)^2}$ measured length in nm.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제9권1호
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• pp.33-38
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• 2020

본 논문에서는 드론에 의하여 획득된 영상을 분석하여 건축자재의 수량을 측정하는 기술을 제안한다. 제안하는 기술은 드론 및 카메라 정보가 담겨있는 드론 로그와 영상 내 건축자재더미 종류와 영역을 예측하는 RCNN, 실제적인 수량 계산을 위한 사진측량법을 사용한다. 기존 연구에선 학습 데이터의 부족으로, 자재 종류 및 건축자재더미 영역 예측 정확도의 오류 범위가 컸다. 논문에서는 이러한 오류 범위를 줄이고 예측 안정성을 높이기 위해 자료 증가 방법으로 학습 데이터를 증가시킨다. 자료 증가는 학습 모델의 과적합을 막기 위해 회전에 의한 증가 방법만 사용한다. 수량 계산 방법으로는 Yaw, FOV 등의 드론 및 카메라 정보가 담겨있는 드론 로그와 영상 내 건축자재더미 영역을 찾고, 종류를 예측해 줄 RCNN 모델을 사용하고, 이 모든 정보를 종합해 논문에서 제안하는 수식에 적용하여 자재더미의 실제적인 수량을 계산한다. 제안하는 방법의 우수성은 실험을 통하여 확인한다.

• 한국음향학회지
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• 제40권4호
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• pp.382-390
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• 2021

해저면 영상을 취득하기 위해 측면주사소나나 다중빔측심기 외에도 합성개구소나가 상용화되어 널리 사용되고 있으며 국내에서도 예인형 시스템 개발 등 관련 연구가 진행 중에 있다. 고해상도의 합성개구소나 영상을 얻기 위해서는 이를 탑재하고 있는 플랫폼의 운동을 정확하게 추정하는 것이 필요하며 이를 위해 정밀한 수중항법 시스템이 요구되고 있다. 본 논문에서는 합성개구소나를 탑재하고 있는 플랫폼의 운동 특성에 따라 소나 영상의 왜곡이 얼마나 발생하는지 정량적으로 분석함으로써 요구되는 항법 정확도와 항법센서의 정밀도를 설정하는데 있어서 기준이 되는 자료를 제공하고자 한다. 총 다섯가지의 운동을 고려하고 있으며 정량적 분석을 위해 정규화된 평균 제곱근 오차를 정의한다. 각 운동 특성의 변수값 변화에 따른 오차 분석 수치해석을 통해 yaw and sway 운동이 가장 큰 영상 왜곡을 야기하며 pitch and heave 운동의 영향은 크지 않음을 확인하였다.

• 제어로봇시스템학회논문지
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• 제19권8호
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• pp.661-666
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• 2013

A state feedback controller with integration of output error is proposed for way-point tracking of an AUV (Autonomous Underwater Vehicle). For the steering control on the XY plane, the proposed controller uses three state variables (sway velocity, yaw rate, heading angle) and the integral of the steering error, and for the depth control on the XZ plane, it uses four state variables (pitch rate, depth, pitch angle) and the integral of the depth error. From the simulation using Matlab/Simulink, we verify that the performance of the proposed controller is satisfactory within an error range of 1m from the target way-point for arbitrarily chosen sets of consecutive way-points.

• 로봇학회논문지
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• 제17권1호
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• pp.25-31
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• 2022

Moving among multiple floors is one of the most challenging tasks for indoor autonomous robots. Most of the previous researches for indoor mapping and localization have focused on singular floor environment. In this paper, we present an algorithm that creates a multi-floor map using 3D point cloud. We implement localization within the multi-floor map using a LiDAR and an IMU. Our algorithm builds a multi-floor map by constructing a single-floor map using a LOAM-based algorithm, and stacking them through global registration that aligns the common sections in the map of each floor. The localization in the multi-floor map was performed by adding the height information to the NDT (Normal Distribution Transform)-based registration method. The mean error of the multi-floor map showed 0.29 m and 0.43 m errors in the x, and y-axis, respectively. In addition, the mean error of yaw was 1.00°, and the error rate of height was 0.063. The real-world test for localization was performed on the third floor. It showed the mean square error of 0.116 m, and the average differential time of 0.01 sec. This study will be able to help indoor autonomous robots to operate on multiple floors.

• 해양환경안전학회지
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• 제27권5호
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• pp.557-565
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• 2021

경로추종 제어는 대양에서 선박의 자율운항을 위한 가장 기본적인 연구 중에 하나로 여겨진다. 본 연구는 선수미방향, 횡방향 및 회두방향으로 외력이 작용하는 경로추종 제어를 다룬다. 가상의 선박에서 발생하는 항로를 자선이 추종하는 문제를 해결하기 위해서 유도 원리와 백스테핑 기법을 활용하였다. 경로추종 제어에서 가장 중요한 기술 중에 하나는 오차 동역학에 관한 것으로서, 이 개념은 선박의 자동 충돌 회피 및 자동 접안 제어 등과 같은 연구 영역에서도 활용이 가능하다. 유도 원리와 오차 변수의 알고리즘은 수치 시뮬레이션을 통해 증명하였다. 그 결과, 회두각의 오차를 제외한 대부분의 오차 변수는 제어기를 통하여 제로 값으로 수렴하였다. 기존에 근거리 통항선박의 간섭력을 고려한 안전통항거리의 값보다 두 선박 간의 경로추종 제어의 트래킹 오차의 값이 더 작은 점이 가장 흥미로운 결과 중에 하나로 여겨진다. 또한 프로펠러, 핀이나 러더와 같은 엑츄에이터의 손상을 줄이기 위해서는 수렴의 성능과 선박의 안전을 절충하여 적합한 제어 파라미터를 결정할 필요가 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.762-766
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• 2003

In this paper, we present a new approach to solve the problem of estimating the camera 3-D location and orientation from a matched set of 3-D model and 2-D image features. An iterative least-square method is used to solve both rotation and translation simultaneously. Because conventional methods that solved for rotation first and then translation do not provide good solutions, we derive an error equation using roll-pitch-yaw angle to present the rotation matrix. To minimize the error equation, Levenberg-Marquardt algorithm is introduced with uniform sampling strategy of rotation space to avoid stuck in local minimum. Experimental results using real images are presented.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.855-860
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• 2007

This paper describes a human driver model developed based on finite preview optimal control method. The human driver steering model is constructed to minimize a performance index which is a quadratic form of lateral position error, yaw angle error and steering input. Simulation studies are conducted using a vehicle simulation software, Carsim. The Carsim vehicle model is validated using vehicle test data. In order to validate the human driving steering model, the human driver steering model is compared to the driving data on a virtual test track(VTT) and the actual vehicle test data. It is shown that human driver steering behaviors can be well represented by the human driver steering model presented in this paper