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No full text학위논문(석사)--아주대학교 일반대학원 :에너지시스템학과,2015. 2현존하는 최첨단 핵융합 장치기술의 총 집합체인 ITER(International Thermonuclear Experimental Reactor; 국제 열핵융합 실험로) 설비는 핵융합 발전을 위한 최종적인 기술 검증이 가능한 시설로써 2020년 시운전을 목표로 현재 프랑스 Cadarache에 건설 중이다. 현재 ITER 프로젝트는 5가지의 난제로 어려움을 겪고 있다. 그 중 하나가 핵융합 반응으로 인하여 생성되는 dust로 인하여 first mirror가 오염이 되는 문제를 안고 있다. 이 문제를 해결하기 위한 첫 번째 방법으로 first mirror 앞에 dust 차단 구조를 설계하여 first mirror로 날아오는 dust를 막는 방법과 두 번째 방법으로 first mirror가 있는 공간의 압력을 dust가 날아오는 공간의 압력보다 높게 만들어 first mirror로 날아오는 dust의 평균행정거리(mean free path)를 짧아지게 만들어 dust가 first mirror까지 도달하지 못하게 막는 구조를 설계하였다. Dust 차단 구조는 Sputter Gun를 사용하여 dust를 만들고 수직 방향에서 Doser로 가스를 분사하여 차단되는 것을 QCM(quartz crystal microbalance; 석영크리스탈마이크로밸런스)을 사용하여 확인하였다. Dust 평균행정거리 감소 구조는 Sputter Gun를 사용하여 dust를 만들고 QCM이 있는 공간에 가스를 주입시켜 주고 가스가 공간에서 쉽게 빠져 나가는 것을 방지하기 위해 baffle를 달아 메인 Chamber와 압력차를 만들어 주어 dust의 평균행정거리를 감소시켜 dust가 QCM에 증착되는 것에 영향이 있는지를 확인하고 분석하였다.제 1 장 서론
제 1 절 연구배경
제 2 절 플라즈마의 정의 및 발생
제 3 절 스퍼터링 현상
제 2 장 본론
제 1 절 Dust 차단 구조
제 2 절 예비 실험
제 1 항 실험 개요
제 2 항 실험 장치 및 방법
제 3 항 실험 결과
제 4 항 분석
제 3 절 DC 마그네트론 스퍼터 건 개선 실험
제 1 항 실험 개요
제 2 항 실험 장치 및 방법
제 3 항 실험 결과
제 4 항 분석
제 4 절 Dust 평균행정거리 감소
제 1 항 실험 개요
제 2 항 실험 장치 및 방법
제 3 항 실험 결과
제 4 항 분석
제 3 장 결론
참고문헌
AbstractMaste
Passivity-based Decentralized Control for Collaborative Grasping of Under-Actuated Aerial Manipulators
Get PDFThis paper proposes a decentralized passive impedance control scheme for
collaborative grasping using under-actuated aerial manipulators (AMs). The AM
system is formulated, using a proper coordinate transformation, as an
inertially decoupled dynamics with which a passivity-based control design is
conducted. Since the interaction for grasping can be interpreted as a feedback
interconnection of passive systems, an arbitrary number of AMs can be modularly
combined, leading to a decentralized control scheme. Another interesting
consequence of the passivity property is that the AMs automatically converge to
a certain configuration to accomplish the grasping. Collaborative grasping
using 10 AMs is presented in simulation.Comment: IEEE International Conference on Robotics and Automation (ICRA) 202
Proprioceptive Sensor-Based Simultaneous Multi-Contact Point Localization and Force Identification for Robotic Arms
Get PDFIn this paper, we propose an algorithm that estimates contact point and force
simultaneously. We consider a collaborative robot equipped with proprioceptive
sensors, in particular, joint torque sensors (JTSs) and a base force/torque
(F/T) sensor. The proposed method has the following advantages. First, fast
computation is achieved by proper preprocessing of robot meshes. Second,
multi-contact can be identified with the aid of the base F/T sensor, while this
is challenging when the robot is equipped with only JTSs. The proposed method
is a modification of the standard particle filter to cope with mesh
preprocessing and with available sensor data. In simulation validation, for a 7
degree-of-freedom robot, the algorithm runs at 2200Hz with 99.96% success rate
for the single-contact case. In terms of the run-time, the proposed method was
>=3.5X faster compared to the existing methods. Dual and triple contacts are
also reported in the manuscript.Comment: 2023 International Conference on Robotics and Automation (ICRA
A Reachability Tree-Based Algorithm for Robot Task and Motion Planning
No full textThis paper presents a novel algorithm for robot task and motion planning (TAMP) problems by utilizing a reachability tree. While tree-based algorithms are known for their speed and simplicity in motion planning (MP), they are not well-suited for TAMP problems that involve both abstracted and geometrical state variables. To address this challenge, we propose a hierarchical sampling strategy, which first generates an abstracted task plan using Monte Carlo tree search (MCTS) and then fills in the details with a geometrically feasible motion trajectory. Moreover, we show that the performance of the proposed method can be significantly enhanced by selecting an appropriate reward for MCTS and by using a pre-generated goal state that is guaranteed to be geometrically feasible. A comparative study using TAMP benchmark problems demonstrates the effectiveness of the proposed approach
A stabilizing controller for regulation of uav with manipulator
Get PDFStability is not trivial in aerial manipulation tasks because of the dynamical coupling between the aerial vehicle and the manipulator. This is especially true when the manipulator becomes heavy, so that its dynamics can be significant. In this letter, a stabilizing controller for the regulation of overall system will be designed without using any assumptions on the dynamic model. In addition, thorough discussion with simulation validation is presented
Design of nonlinear H<inf>∞</inf> optimal impedance controllers
No full textIn this paper, nonlinear H∞ optimal design of impedance controllers is proposed based on the nonlinear robust internal-loop compensator (NRIC) framework. Simply adding PD-type auxiliary input to the original control law, the robust performance and the robust stability are achieved. Nonlinear H∞ optimality is guaranteed by solving Hamilton-Jacobi-Isaacs (HJI) equation and the disturbance input-to-state stability (ISS) is guaranteed by finding ISS-Lyapunov function. Moreover, it is shown that the proposed method preserves the passivity of the impedance controllers. The proposed method can be applied to various types of impedance controllers in a unified way. Through simulations and experimental studies, the proposed method is verified
Nonlinear Disturbance observer design for Euler-Lagrange systems: An initial study
No full textRecently, Disturbance observer(DOB) has been investigated a lot. But it has a defect that it cannot be applied to nonlinear systems. This paper proposes a novel Nonlinear Disturbance observer(NDOB). NDOB consists of internal loop that generates an auxiliary control input that compensates external disturbances. The auxiliary input inversely satisfies nonlinear H∞ optimality and existence of the controller guarantees input-to-state stability of internal loop. Simulation has been performed to verify proposed observer and shows an expected result
Robust control of flexible joint robots based on motor-side dynamics reshaping using disturbance observer (DOB)
No full textThis paper proposes a robust control scheme based on a disturbance observer (DOB) for flexible joint robots. In this paper, the DOB is applied only on the motor-side dynamics of the robot, and the uncertainties on the motor-side are successfully eliminated. It is shown that, to guarantee the stability, the estimated motor-side position should be fed back into the controller, which is different from usual setup of the DOB. The experiments/simulations show that the estimated signal feedback indeed guarantees the stability, whereas the measured signal feedback does not
Applying disturbance observer to the motor side of flexible joint robots with PD control
No full textThis paper demonstrates DOB-based PD+gravity compensation control for flexible joint robots (FJRs). By virtue of the DOB, the controller can recover global asymptotic stability under the friction. One important difference from the typical DOB implementation is that the nominal signal feedback is required, instead of the real (measured) signal feedback
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