• Title/Summary/Keyword: Constraint method

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Analysis and Evaluation for Constraint Enforcement System (제한 시스템의 분석 및 평가)

  • Hong, Min;Park, Doo-Soon;Choi, Yoo-Joo
    • Journal of the Korea Society for Simulation
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    • v.18 no.2
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    • pp.57-64
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    • 2009
  • Stable and effective constraint enforcement system is one of the crucial components for physically-based dynamic simulations. This paper presents analysis and evaluation for traditional constraint enforcement systems(Lagrange Multiplier method, Baumgarte stabilization method, Post-stabilization method, Implicit constraint enforcement method, Fast projection method) to provide a guideline to users who need to integrate a suitable constraint enforcement system into their dynamic simulations. The mathematical formulations for traditional constraint enforcement systems are presented in this paper. This paper describes a summary of evaluation which consists of constraint error comparison, computational cost, and dynamic behavior analysis to verify the efficiency of each traditional constraint enforcement system.

A Formulation of the Differential Equation on the Equations of Motion and Dynamic Analysis for the Constrained Multibody Systems (구속된 다물체 시스템에 대한 운동 방정식의 미분 방정식화 및 동역학 해석)

  • 이동찬;이상호;한창수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.1
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    • pp.154-161
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    • 1997
  • This paper presents the method to eliminate the constraint reaction in the Lagrange multiplier form equation of motion by using a generalized coordinate driveder from the velocity constraint equation. This method introduces a matrix method by considering the m dimensional space spanned by the rows of the constraint jacobian matrix. The orthogonal vectors defining the constraint manifold are projected to null vectors by the tangential vectors defined on the constraint manifold. Therefore the orthogonal projection matrix is defined by the tangential vectors. For correcting the generalized position coordinate, the optimization problem is formulated. And this correction process is analyzed by the quasi Newton method. Finally this method is verified through 3 dimensional vehicle model.

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Energy constraint control in numerical simulation of constrained dynamic system

  • 윤석준
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.376-382
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    • 1991
  • In the analysis of constrained holonomic systems, the Lagange multiplier method yields a system of second-order ordinary differential equations of motion and algebraic constraint equations. Conventional holonomic or nonholonomic constraints are defined as geometric constraints in this paper. Previous works concentrate on the geometric constraints. However, if the total energy of a dynamic system can be computed from the initial energy plus the time integral of the energy input rate due to external or internal forces, then the total energy can be artificially treated as a constraint. The violation of the total energy constraint due to numerical errors can be used as information to control these errors. It is a necessary condition for accurate simulation that both geometric and energy constraints be satisfied. When geometric constraint control is combined with energy constraint control, numerical simulation of a constrained dynamic system becomes more accurate. A new convenient and effective method to implement energy constraint control in numerical simulation is developed based on the geometric interpretation of the relation between constraints in the phase space. Several combinations of energy constraint control with either Baumgarte's Constraint Violation Stabilization Method (CVSM) are also addressed.

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Numerical method to impose constraint conditions in phase transformation (상변태의 구속 조건을 부가하기 위한 수치 방법)

  • Yang, Seung-Yong;Goo, Byeong-Choon
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.706-709
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    • 2004
  • A numerical method was developed that imposes constraint condition on the order parameters in martensitic phase transformation. In the method, an amplitude function having values of 1 or 0 was multiplied to transformation rates. The merit of the method is that the imposition of the constraint condition is more straightforward than a method with Lagrangian multiplier and easy to implement in the tangent modulus method. The developed method is applied to three-dimensional finite element analyses of single and poly crystalline shape memory alloys.

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Constraint Programming Approach for a Course Timetabling Problem

  • Kim, Chun-Sik;Hwang, Junha
    • Journal of the Korea Society of Computer and Information
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    • v.22 no.9
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    • pp.9-16
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    • 2017
  • The course timetabling problem is a problem assigning a set of subjects to the given classrooms and different timeslots, while satisfying various hard constraints and soft constraints. This problem is defined as a constraint satisfaction optimization problem and is known as an NP-complete problem. Various methods has been proposed such as integer programming, constraint programming and local search methods to solve a variety of course timetabling problems. In this paper, we propose an iterative improvement search method to solve the problem based on constraint programming. First, an initial solution satisfying all the hard constraints is obtained by constraint programming, and then the solution is repeatedly improved using constraint programming again by adding new constraints to improve the quality of the soft constraints. Through experimental results, we confirmed that the proposed method can find far better solutions in a shorter time than the manual method.

Design of a Robust Controller Using Genetic Algorithms and LMI Design Method (유전자 알고리즘과 LMI 설계 방법을 이용한 강인 제어기의 설계)

  • Lee, Moon-Noh;Lee, Hong-Kyu
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.7
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    • pp.619-624
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    • 2011
  • This paper presents a controller design method for a robust control problem with multiple constraints using genetic algorithms and LMI design method. A robust $H_{\infty}$ constraint with loop shaping and pole placement is used to address disturbance attenuation with error limits and desired transient specifications, in spite of the plant uncertainties and disturbances. In addition, a loop gain constraint is considered so as not to enlarge the loop gain unnecessarily. The robust $H_{\infty}$ constraint and pole placement constraint can be expressed in terms of two matrix inequalities and the loop gain constraint can be considered as an objective function so that genetic algorithms can be applied. Accordingly, a robust controller can be obtained by integrating genetic algorithms with LMI approach. The proposed controller design method is applied to a track-following system of an optical disk drive and is evaluated through simulation results.

A Study of the Value of Travel Time Reliability (통행시간 신뢰성 가치에 관한 연구)

  • Cho, Hanseon
    • International Journal of Highway Engineering
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    • v.15 no.4
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    • pp.155-165
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    • 2013
  • PURPOSES : Benefits for improvement of travel time reliability obtained from construction of new highways should be considered as a major factor in the feasibility study for highway constructions. The purpose of this study is to develop a method of estimation for the value of travel time reliability. METHODS : Highway type (urban/rural highway) and traffic flow type(interrupted/uninterrupted) was considered to estimate he value of travel time reliability. And Double-bounded Dichotomous Choice among Contingent Valuation Method(CVM) was applied to survey the willingness-to-pay of drivers when travel time reliability is improved. Finally the value of travel time reliability was estimated using the results of survey and logit model. The value of travel time reliability was estimated considering travel objectives, time constraint travel and non-time constraint travel. RESULTS: The value of travel time reliability of business trip is higher than that of non-business trip. The value of travel time reliability of time constraint travel is higher than that of non-time constraint travel. The value of travel time reliability in urban area is higher than that in rural area. CONCLUSIONS: It was concluded that the proposed method in this study is more realistic and proper to estimate the value of travel time reliability because it reflects the situations of time constraint travel and non-time constraint travel.

A GA-based Floorplanning method for Topological Constraint

  • Yoshikawa, Masaya;Terai, Hidekazu
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.1098-1100
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    • 2005
  • The floorplanning problem is an essential design step in VLSI layout design and it is how to place rectangular modules as density as possible. And then, as the DSM advances, the VLSI chip becomes more congested even though more metal layers are used for routing. Usually, a VLSI chip includes several buses. As design increases in complexity, bus routing becomes a heavy task. To ease bus routing and avoid unnecessary iterations in physical design, we need to consider bus planning in early floorplanning stage. In this paper, we propose a floorplanning method for topological constraint consisting of bus constraint and memory constraint. The proposed algorithms based on Genetic Algorithm(GA) is adopted a sequence pair. For selection control, new objective functions are introduced for topological constraint. Studies on floor planning and cell placement have been reported as being applications of GA to the LSI layout problem. However, no studies have ever seen the effect of applying GA in consideration of topological constraint. Experimental results show improvement of bus and memory constraint.

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Efficient Spatial Query Processing in Constraint Databases (제약 데이터베이스에서의 효율적인 공간질의 처리)

  • Woo, Sung-Koo;Ryu, Keun-Ho
    • Journal of Korea Spatial Information System Society
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    • v.11 no.1
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    • pp.79-86
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    • 2009
  • The tuple of constraint database consists of constraint logical formula and it could process the presentation and query of the constraint database simply. Query operation processing shall include the constraint formula between related tuple such as selection, union, intersection of spatial data through the constraint database. However, this could produce the increasing of duplicated or unnecessary data. Hence, it will drive up the cost as per quality. This paper identified problems regarding query processing result in the constraint database. Also this paper suggested the tuple minimization summary method for result relation and analyzed the effects for efficient query processing. We were able to identify that the effectiveness of the query processing was enhanced by eliminating unnecessary constraint formula of constraint relation using the tuple minimization method.

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Photometric Stereo Calibration using Constraint on Light Source Directions (광원 방향에 대한 제한조건을 이용한 Photometric Stereo Calibration)

  • Jeong, Seong-Cheol;Nguyen, Viet Hung;Won, Sang-Chul
    • IEMEK Journal of Embedded Systems and Applications
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    • v.8 no.2
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    • pp.111-119
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    • 2013
  • This paper proposes one method on photometric stereo calibration using the constraint on light source directions in which the light sources have the unknown tilt and slant angles but the slant angles are the same. First, the constraint is analyzed based on the equation of linear ambiguity which leads to the conclusion that another constraint should be added to solve the calibration completely. Later, the combination of constraint on light source directions and the constraint that there exists at least six surface patches having known albedos is exploited to resolve the linear ambiguity up to an accurate and close-form solution. The effective performance of the proposed method is demonstrated through experiment results.