• Title/Summary/Keyword: 다물체 시스템

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Multiple-Model Probabilistic Design for Centralized Repetitive Controllers of Multiple Systems (다물체시스템의 중앙집중 연속학습제어 복수모형 확률설계기법)

  • Lee, Soo-Cheol
    • Journal of Korea Society of Industrial Information Systems
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    • v.16 no.4
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    • pp.99-105
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    • 2011
  • This paper presents a method to design a centralized repetitive controller that is robust to variations in the multiple system parameters. The uncertain parameters are specified probabilistically by their probability distribution functions. Instead of working with the distribution functions directly, the centralized repetitive controller is designed from a set of models that are generated from the specified probability functions. With this multiple-model design approach, any number of uncertain parameters that follow any type of distribution functions can be treated. Furthermore, the controller is derived by minimizing a frequency-domain based cost function that produces monotonic convergence of the tracking error as a function of repetition number. Numerical illustrations show how the proposed multiple-model design method produces a repetitive controller that is significantly more robust than an optimal repetitive controller designed from a single nominal model of the multiple system.

3D Object Recognition with Hierarchical Feature Learning (계층적 특징 학습을 이용한 3차원 물체 인식)

  • Kim, Joo-Hee;Kim, Dong-Ha;Kim, In-Cheol
    • Proceedings of the Korea Information Processing Society Conference
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    • 2015.04a
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    • pp.762-765
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    • 2015
  • 본 논문에서는 물체의 모양 정보를 나타내는 물체 표면의 법선 벡터 데이터와 컬러 영상으로부터, 강한 표현력을 갖도록 학습을 통해 특징을 추출하는 효과적인 물체 인식 시스템을 제안한다. 본 논문에서 제안하는 물체 인식 시스템에서는 입력되는 깊이 영상을 물체 표면의 법선 벡터로 변환하여, 단순한 거리 측정치를 물체 인식에 유리한 표면 모양 정보로 활용하였을 뿐 아니라 센서 위치나 방향에 대한 의존성을 감소시켰다. 또한, 본 시스템에서는 실세계의 수많은 물체들의 고유한 특성들을 잘 표현해 줄 수 있도록, 다계층 학습을 통하여 특징을 추출하였다. 워싱턴 대학의 RGB-D 물체 데이터 집합을 이용하여 다양한 성능 분석 실험을 수행하였고, 이를 통해 본 논문에서 제안하는 물체 인식 시스템의 높은 성능을 확인할 수 있었다.

Study on Parallel Processing for Efficient Flexible Multibody Analysis based on Subsystem Synthesis Method (병렬 처리를 이용한 부분 시스템 기반 유연다물체 동역학의 효율적인 해석 연구)

  • Han, Jong-Boo;Song, Hajun;Kim, Sung-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.6
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    • pp.507-515
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    • 2017
  • Flexible multibody simulations are widely used in the industry to design mechanical systems. In flexible multibody dynamics, deformation coordinates are described either relatively in the body reference frame that is floating in the space or in the inertial reference frame. Moreover, these deformation coordinates are generated based on the discretization of the body according to the finite element approach. Therefore, the formulation of the flexible multibody system always deals with a huge number of degrees of freedom and the numerical solution methods require a substantial amount of computational time. Parallel computational methods are a solution for efficient computation. However, most of the parallel computational methods are focused on the efficient solution of large-sized linear equations. For multibody analysis, we need to develop an efficient formulation that could be suitable for parallel computation. In this paper, we developed a subsystem synthesis method for a flexible multibody system and proposed efficient parallel computational schemes based on the OpenMP API in order to achieve efficient computation. Simulations of a rotating blade system, which consists of three identical blades, were carried out with two different parallel computational schemes. Actual CPU times were measured to investigate the efficiency of the proposed parallel schemes.

A Non-recursive Formulation of Dynamic Force Analysis in Recursive Multibody Dynamics (순환 다물체동역학에서의 비순환적인 동하중해석 공식)

  • Kim, Seong-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.5
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    • pp.809-818
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    • 1997
  • An efficient non-recursive formulation of dynamic force analysis has been developed for serially connected multibody systems. Although derivation of equations of motion is based on a recursive dynamic formulation with joint relative coordinates, in the proposed formulation, dynamic forces such as joint reaction forces and driving force are computed non-recursively for specified joints. The efficiency of the proposed formulation has been proved by the operational count and the CPU time measure, comparing with that of the conventional recursive Newton-Euler formulation. A simulation of 7-DOF RRC robot arm has been carried out to validate solutions of reaction forces by comparing with those from a commercial dynamic analysis program DADS.

A Study on Resonance Durability Analysis of Vehicle Suspension System (차량 현가 시스템의 공진내구해석에 대한 연구)

  • 이상범;한우섭;임홍재
    • The Journal of the Acoustical Society of Korea
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    • v.22 no.6
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    • pp.512-518
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    • 2003
  • In this paper, resonance durability analysis is performed for the fatigue life assessment considering vibration effect of a vehicle system. In the resonance durability analysis, the frequency response and the dynamic load on frequency domain are used. Multi-body dynamic analysis, finite element analysis, and fatigue life prediction method are applied for the virtual durability assessment. To obtain the frequency response and the dynamic load history, the computer simulations running over typical pothole and Belgian road are carried out by utilizing vehicle dynamic model. The durability estimations on the rear suspension system of the passenger car are performed by using the resonance durability analysis technique and compared with the quasi-static durability analysis. The study shows that the fatigue life considering resonant frequency of vehicle system can be effectively estimated in early design stage.

A Dynamic Analysis of Constrained Multibody Systems (구속된 다물체 시스템을 위한 동역학 해석론)

  • 이상호;한창수;서문석
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.9
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    • pp.2339-2348
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    • 1994
  • The objective of this paper is to develop a solution method for the differential-algebraic equation(DAE) derived from constrained muti-body dynamic systems. Mechanical systems are often modeled as bodies and joints. Differential equations of motion are formulated for bodies. Since the bodies are connected by joint, the differential variables must satisfy the kinematic constraint equations that come from the joints. Difficulties are arised due to drift of the differential variables off the constraint equations. An optimization method is adopted to correct the drift of the differential variables. To demonstrate the efficiency of the proposed method a slider-crank mechanism is analyzed dynamically. Identical results are obtained as these from the commercial program DADS. Dynamic analysis of a High Mobility Multi-purpose Wheeled. Vehicle(HMMWV) is carried out to show the practicalism of the proposed method.

Development of a Internet-based Dynamic Simulation System for Multibody Systems (인터넷 기반 범용 다물체 동역학 시뮬레이션 시스템 개발)

  • Lee, Jai-Kyung;Han, Hyung-Suk;Seo, Jong-Whi;Park, Tae-Won
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.699-704
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    • 2003
  • A Internet-based dynamic simulation system, called P-DYN, for multibody dynamic systems is developed. All the interfaces of the system are accessible via Web browsers, such as Netscape or Explorer. The system uses a template type P-DYN/Modeler as a preprocessor. The P-DYN postprocessor composed of P-DYN/Plotter and P-DYN/Animator is developed in JAVA. The P-DYN/Solver for predicting the dynamic behavior is run on the server. Anyone who wants to simulate the dynamics of multibody systems or share results data can access the analysis system over the Internet regardless of their OS, platform, or location.

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Gun System Vibration Analysis using Flexible Multibody Dynamics (유연 다물체 동역학을 이용한 포신-포탑시스템의 진동해석)

  • 김성수;유진영
    • Journal of KSNVE
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    • v.8 no.1
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    • pp.203-211
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    • 1998
  • In order to find out relationship between hit probability and gun firing of a moving tank, a turret and flexible gun system model has been developed using a recursive flexible multibody dynamics. For a firing simulation model, nodal coordinates for a finite element model of a flexible gun have been employed to include transverse loads to the gun tube due to moving bullet and ballistic pressure. Modal coordinates are also used to represent the motion induced gun vibration before a firing occurs. An efficient switching technique from modal equations to nodal equation has been introduced for an entire gun firing simulation with a rotating turret.

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Construction of Allowable Load Set for Multi-body Systems and Application Cases (다물체 시스템에서의 허용하중 집합의 구현과 적용)

  • Kim, J.H.;Kwak, B.M.
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.758-763
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    • 2001
  • A concept called Allowable Load Set (ALS) is introduced and methods of finding its boundaries are developed. The resulting diagram allows an easy understanding of load and strength characteristics of a structure in relation to structural integrity under uncertain loading conditions. An allowable load diagram for an ALS visualizes the relation between a prescribed load and a degree of safety of the structure. During the application of the algorithms, critical areas of the structure are identified. A systematic method of finding the allowable load sets for multi-body mechanical systems is especially presented and applied to an excavator as a realistic case.

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Shock and vibration analysis of a tractor-trailer type vehicle system with air suspension (공기 현가 장치를 장착한 트랙터-트레일러형 차량 시스템의 충격진동 해석)

  • 김종길;하태완
    • Journal of the Korea Institute of Military Science and Technology
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    • v.3 no.2
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    • pp.15-22
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    • 2000
  • Shock and vibration characteristics of a tractor-trailer type vehicle system with air suspension and air coupler running on a single bump road are investigated. The vehicle system is modelled and solved to two types of models, i.e. rigid-multi-body and flexible-multi-body model, by ADAMS and NASTRAN software. And the shock impulse is given by a single bump model on the road. When the analysis results of the rigid-multi-body model is compared with those of the flexible-multi-body model, it is revealed that the vibration and accelerations of the latter model are more repetitive and larger than the former.

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