• 제목/요약/키워드: velocity ellipsoid

검색결과 22건 처리시간 0.023초

Impact Reduction for Unknown Environment Using Kinematic Redundancy

  • Kim, Jinhyun;Chung, Wan-Kyun;Youngil Youm
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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    • pp.25-28
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    • 1999
  • In this article, a new performance index is proposed to re-duce the collision impulsive force by controlling the null motion of redundant manipulators. First, we define the normalized impact ellipsoid in the viewpoint of instantaneous velocity change. Then, we propose a new impact performance index based on velocity direction for null motion to reduce initial impulsive effects. It gives some advantage for the case of unknown environment. The optimization of this index is that the successional impact forces are reduced. The performance of the proposed index is demonstrated by simulation study.

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병렬형 공작기계의 조작성 해석: 기구부 최적설계에 적용 (Manipulability Analysis of a Parallel Machine Tool: Application to Optimal Link Parameters Design)

  • 김점구;홍금식;박종우;김종원`
    • 한국정밀공학회지
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    • 제16권11호
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    • pp.213-223
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    • 1999
  • In this paper, input-output transmission characteristics of the Eclipse, which is a parallel machine tool capable of 5 face rapid machining, are investigated. By splitting the weighted Jacobian matrix into two parts, the force and moment transmission characteristics together with the velocity and angular velocity transmission characteristics are analyzed. A new manipulability measure, which combines the volume of the manipulability ellipsoid and the condition number of the splitted Jcobian matrix, is proposed. Two link parameters, the ratio of upper and lower platforms' radii and the length of a supporting link of the Eclipse, are designed by applying the new manipulability measure derived. Computer simulations are provided.

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조작지수에 근거한 수중로봇팔의 작업지향적 최적자세에 관한 연구 (A Study on the Task-Oriented Optimal Configuration of an ROV Mounted Manipulator Based on the Manipulability Measure)

  • 김인식;전봉환;이판묵;이지홍
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2004년도 학술대회지
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    • pp.48-53
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    • 2004
  • In this paper, the task-oriented optimal configuration in the sense of Velocity and Force manipulability measure of manipulator mounted on ROV is considered. Manipulability is a quantitative measure of manipulator's capability obtained under the limits of joint velocities or torques. The base arrangements and optimal joint configuration of manipulator, that maximize the manipulability measure under the constraints of given task, are investigated. With the two types of base arrangements of manipulator, workspace analysis is carried out to investigate merits and demerits of each arrangement on the view of manipulability measure. To find optimal joint configuration for a given task with each arrangement, the SQP(Sequential Quadratic Programming) optimization are performed. Weighted linear combination of velocity and force manipulability measure is object function for SQP optimization. The kinematic parameters of Dual Orion manipulator which will be mounted on KORDI ROV are used for simulation.

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병렬구조 신 압연기의 최적설계 : 조작성 및 제어성능의 최대화 (Optimal Design of a New Rolling Mill Based upon Stewart Platform Manipulator : Maximization of Kinematic Manipulability)

  • 홍금식;이승환;최진태
    • 제어로봇시스템학회논문지
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    • 제8권9호
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    • pp.764-775
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    • 2002
  • A kinematic and dynamic optimal design of a new parallel-type rolling mill based upon Stewart platform manipulator is investigated. To provide sufficient degrees-of-freedom in the rolling process and the structural stability of each stand, a parallel manipulator with six legs is considered. The objective of this new parallel-type rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of the rolls, and tension of the strip. By splitting the weighted Jacobian matrices Into two parts, the linear velocity, angular velocity, force, and moment transmissivities are analyzed. A manipulability measure, the ratio of the manipulability ellipsoid volume and the condition number of a split Jacobian matrix, is defined. Two kinematic parameters, the radius of the base and the angle between two neighboring Joints, are optimally designed by maximizing the global manipulability measure in the entire workspace. The maximum force needed in the hydraulic actuator is also calculated using the structure determined through the kinematic analysis and the Plucker coordinates. Simulation results are provided.

자유표면하에서 전진하는 3차원 물체 주위의 양력 흐름 수치 해석 (Numerical Analysis of Lifting Potential Flow around a Three-Dimensional Body moving beneath the Free Surface)

  • 김부기
    • 대한조선학회논문집
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    • 제29권3호
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    • pp.21-32
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    • 1992
  • 자유 수면하를 영각을 가지고 일정 속도로 전진하는 3차원 물체가 만드는 자유 표면 흐름에 대한 수치해를 보인다. 해를 구하기 위해 물체 표면에 Havelock 쏘오스와 법선 다이폴을, Wake 면에는 Havelock 법선 다이폴을 분포시키는 교란 속도 포텐시얼을 기저로 한 패널법을 이용하였다. Trailing Edge의 윗면과 아랫면의 압력 등가 조건을 정확히 만족시키기 위해 반복 기법을 이용한 압력 Kutta 조건을 사용하였다. 무한 유체 영역에 놓인 Ellipsoid와 사각 Wing에 대해 계산 프로그램을 검증한 후 자유 수면하에 잠수하여 전진하는 Spheroid와 스트럿에 대한 문제를 다루었다. 본 연구에서 채택한 Panel Method는 자유 표면 효과, 3차원 물체의 형상을 고려하여 물체에 작용하는 동유체력을 비교적 정확하게 예측하였으며 특히 Wake 형상은 동유체력 계산에 큰 영향을 미치지 않는 것으로 확인하였다.

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Modeling of External Impulse via the Concept of an Effective Mass in Sawing Task

  • Lee, Jae-Hoon;Park, Byung-Joon;Yi, Byung-Ju;Suh, Il-Hong
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2003년도 ICCAS
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    • pp.2713-2718
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    • 2003
  • Some of manufacturing tasks such as sawing task often requires continuous impulsive motion. In case of sawing task, such impulsive motions can be observed between the teeth of the saw and the object. The amount of the external impulse exerted on the object has been treated as an important control parameter. The purpose of this work is to introduce a new concept of an effective mass in sawing task and to suggest an external impulse model in sawing task. A normalized impulse ellipsoid reflecting the velocity direction is employed to visualize the impact geometry. Experiments are performed for soft and hard workpieces to justify the external impulse model in the sawing task. It is demonstrated through simulation and experiment that the proposed external impulse model is effective to characterize the impact property.

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속도 제한에 의한 충격량 도형에 관한 연구 (An analysis on the robotic impact geometry with task velocity constraint)

  • 이지홍
    • 제어로봇시스템학회논문지
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    • 제5권8호
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    • pp.955-960
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    • 1999
  • This paper describes the effect of impact configurations on a single robot manipulator. The effect of different configurations of kinematically redundant arms on impact forces at their end effectors during contact with the environment is investigated. Instead of the well-known impact ellipsoid, I propose an analytic method on the geometric configuration of the impact directly from the mathematical definition. By calculating the length along the specified motion direction and volume of the geometry, we can determine the characteristics of robot configurations in terms of both the impact along the specified direction and the ability of the robot withstanding the impact. Simulations of various impact configurations are discussed at the end of this paper.

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매스콘크리트 교각의 수화열에 의한 온도 및 응력 거동에 대한 3차원 유한요소 해석 (A 3-dimensional Finite Element analysis of the Temperature and Stress Development in Mass Concrete Pier due to Heat of Hydration)

  • 주영춘;김은겸;신치범
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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    • pp.928-933
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    • 1998
  • The temperature and stress behaviour of mass concrete pier at early ages was analysed based on the finite element method. The pier investigated is a three-dimensional structure of which the cross-sectional shape varies from a circle to an ellipsoid along the longitudinal axis. In order to obtain the transient temperature and stress distributions in the structure, a three dimensional method was adopted, because the structure of this type cannot be modeled accurately by a two-dimensional method. Temperature analysis was performed by taking into consideration of the cement type and content, boundary and environment conditions including the variations of atmospheric temperature and wind velocity. The results of this study may be useful for the temperature control to restrain thermal cracking and the construction management to design the resonable curing method of mass concrete structure.

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SenSation : A New Translational 2 DOF Haptic Device with Parallel Mechanism

  • Chung, Young-Hoon;Lee, Jae-Won
    • Transactions on Control, Automation and Systems Engineering
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    • 제3권4호
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    • pp.217-222
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    • 2001
  • We propose a new two-degree of freedom parallel mechanism for a haptic device and will refer to the mechanism as the SenSation. The SenSation is designed in order to improve the kinematic performanced and to achieve static balance. We use the panto graph mechanisms in order to change the location of active joints, which leads to transform a direct kinematic singularity into a nonsingularity. The direct kinematic singular configurations of the SenSation occur near the workspace boundary. Using the property that position vector of rigid body rotating about a fixed point is normal to the velocity vector, Jacobian matrix is derived. Using the vector method, two different types of singularities of the SenSation can be identified and we discuss the physical significance of each of the three types of singularities. We will compare the kinematic performances(force manipulability ellipsoid, kinematic isotropy) of the SenSation with those of five-var parallel mechanism. By specifying that the potential energy be fixed, the conditions for the static balancing of the SenSation is derived. The static balancing is accomplished by changing the center of mass of the links.

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마찰력이 개재된 3차원 강체충돌 해석 - 타원체간 충돌 - (Analysis of Three-Dimensional Rigid-Body Collisions with Friction -CoIlisions between EIlipsoids-)

  • 한인환;조정호
    • 대한기계학회논문집A
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    • 제20권5호
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    • pp.1486-1497
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    • 1996
  • The problem of determining the 3-demensional motion of any two rough bodies after a collision involves some rather long analysis and yet in some points it differs essentially from the corresponding problem in tdwo dimensions. We consider a special problem where two rough ellipsolids moving in any manner collide, and analyze the three dimensional impact process with Coulomb friction and Poisson's hypothesis. The differential equations that describe that process of the impact induce a flow in the tangent velocity space, the flow patterns characterize the possible impact cases. By using the graphic method in impulse space and numerical integration thchnique, we analyzed the impact process inall the possible cases and presented the algorithm for determining the post-impact motion. The principles could be applied to the general problem in three dimensions. We verified the effectiveness of the analysis results by simulating the numerous significant examples.